Thesis & Projects

Abstract
Increasing the cuttings transport performance in deviated wells is difficult due to the rolling transport and cuttings settling on the low side of the annulus. Insufficient cuttings transport may lead to some crucial problems such as pipe sticking, increasing in torque and drag, material damage and bed cementing quality. Increasing flow rates and improving mud properties may not be applicable for a proper hole cleaning because of the hydraulic and mechanical limitations. In such cases, additional pressure may be generated, and this causes formation fractures and drilling fluid losses. Under these circumstances, the other major contribution to cuttings transport is provided by drill-pipe rotation for different eccentricity. This project describes the relation between hole eccentricity and rotation during cuttings transport through annular bends.

The present study focused on the development of a computational fluid dynamics model to predict these parameters conveniently  and accurately. Two phases-liquid (water) and cuttings (sulfur solid) were considered. The simulations were conducted using the workbench platform of ANSYS Fluent 2021 R1. The Eulerian model of multiphase flow and the Reynolds stress model of turbulence closure available in Fluent were used for the present study. The average velocities and volumetric concentrations of involved phases were specified as the inlet boundary conditions. The stationary surfaces of the flow channels were hydrodynamically considered as either smooth or rough walls, and the outlets were regarded as being open to the atmosphere. The simulation results of pressure loss showed a good agreement with the predictions of well-established correlations.

From the simulated results, this project concludes that drill cuttings transport efficiency depends on hole eccentricity and drill pipe rotation of the models where pressure and VOF of cuttings are maximum with minimum pressure drop. For eccentricity 0.4 with 200 rpm simulation shows maximum pressure at outlet with maximum cuttings VOF and also shows minimum pressure drop than other models at outlet.
 

Abstract
The study focuses on the utilization of Integrated Production Modeling (IPM) of Subjected Gas Field located in South-Eastern region of Bangladesh. The gas filed has five wells while four are producing with a processing facility of 120 MMscfd gas dehydration plant. Currently, the field produces around 95 MMscfd gas and 280 bbl/d condensate. A study in 2006 estimated the reserve of this field as 0.476 Tef. Currently the field is struggling to maintain a plateau rate due to depletion. It is therefore necessary to adopt an optimized production and development strategy for this field.

The goal of this study is to re-estimate the gas reserve and suggest an optimum field development strategy based on gas recovery factor and plateau duration.

The task was divided into several steps, including reserve estimation, gravel pack design for the sand producing well and future performance prediction for 20 different scenarios. The work involves integration of reservoir, wells and surface facilities in an integrated model, several field development strategies with varying production system were investigated. These include reviving the shut in well, lowering separator pressure, installation of compressor, and adding an infill well.

This study estimated the reserve of the field as 1.23 Tef by material balance method. Comparative analysis of the various predictive cases suggests the following optimum development strategy a) Installation of compressor in wellhead along with infill well, resulting in maximum recovery 77.45% b) tie-in sand producing well with gravel pack, resulting in maximum recovery 69.24%. A recovery factor 60.27% is achievable using the current field production strategy.
 

Abstract
Lubricating oil is called the 'Blood of an engine and machine'. The performance, desired service life, energy-economic efficiency of an engine and machine depends on quality of lubricants. However, adequate codes and standards, regulations, policies, guidelines and enforcement towards the effective quality control and application of lubricants are not up to date in Bangladesh. Proper implementation and monitoring of lubricating oil market are not sufficient to control proper management system. Adulteration of lubricating oil is common scenario in Bangladesh lubricating oil market, which causing damage to the durability of engines. Guidelines for law enforcement and punishments are needed to control adulterations. Used lubricants are harmful for environment and thus, the base oil can be used after re-refining for producing blended lubricants after mixing with additives in appropriate proportion.
Therefore, the current study was carried out to study the recent acts, notification, regulations. codes and standards of lubricants used for lubricating oil business. The study was carried out demand and supply trends of lubricants and environment impacts and proper disposal of used lubricants. The study also aimed to detect the opportunities of entering adulterated and sub- standard lubricating oils in the local market. For this purpose, three different categories of adulterated oil samples were collected and tested to conduct comparisons study. The study also reported the base oil recovery process from waste lubricants and its management system.
Based on literature survey it can be seen that globally the latest engine oil service category API (American Petroleum Institute) SN with resource conservation was established for gasoline engine. However, in Bangladesh API SJ, SG/CC category using as the latest lubricant standard for gasoline engine which is not compatible. On the other hand, API CF combined with ACEA 96 E2 and ACEA 96 E2 are the latest lubricant standards used for diesel engine in Bangladesh although those are obsolete according to API and ACEA standards for new model vehicles. Adulterated lubricating oil test results show that the difference between adulterated and original oil is difficult to tell. To find out adulterated lubricating oil, infrared spectrum test is more accurate than other tests. The engines of vehicles are getting damaged within a short service time for using the adulterated lubricants. The lack of regulatory control has led to unscientific disposal of hazardous waste throughout the country, posing serious risks to public health and the environment.
 

Abstract
Wellbore instability is one of the most prevalent downhole challenges since oil well drilling began. The difficulties become more profound and unpredictable when the wells are exploratory. Wellbore Instability issues related to exploratory wells causes significant amount of non- productive time (NPT). These problems could lead to fishing operation and sidetrack which may cause greater financial loss. In Bangladesh wellbore related issues especially stuck pipe cases were experienced from time to time. This work analyzes the wellbore instability incidents of two exploratory wells, Mubarakpur-1 and Sunetro-1.

Based on available data like Geological Technical Order (GTO), Daily Drilling Reports, Well Logging Reports, Mud Reports, XRD (X-ray Diffraction) reports, Cavings samples with pictures, Well Completion Report etc. this work presents the sequence of events leading to the stuck pipe incident on Mubarakpur-1 and Sunetro-1 wells. Based on available information the root cause(s) of wellbore instability issues of the said wells have been analyzed and suggestions have been made on how to drill similar wells while tackling such issues in future.

Mubarakpur-1 and Sunetro-1 are different in geological aspects. Formation pressure and wellbore stresses were higher in Mubarakpur-1 than Sunetro-1. Shale formation showed non- reactive character in Mubarakpur-1, whereas Sunetro-1 suffered from shale swelling effect. Both wells encountered stuck pipe incidents but the sequences of events were different. Mubarakpur-1 faced compressive failure due to stress concentration around the wellbore. And Sunetro-1 crossed the reactive shale instability which resulted in hole pack-off. Some operational mishaps were also responsible for both stuck pipe incidents. The analysis showed that focus should be given on understanding the in-situ stress condition while drilling, identifying formation type. So that appropriate mud weight selection, BHA design can be implemented for trouble free operation.
 

Abstract
Natural Fractures play an important role in oil and gas industry because of their capability of providing pathway for hydrocarbon flow in geologic formations. Fractures connect pores together, therefore, enhance the oil and gas production from a reservoir by increasing the permeability. On the other hand, presence of fractures makes a drilling operation challenging because drilling fluid got lost into them, which in turn increases the drilling cost. The aim of this paper is to carry out a Computational Fluid Dynamics (CFD) study of drilling fluid flow in natural fractures to improve comprehensive understanding of the flow in fractured media.

The study was carried out by creating a three-dimensional steady state CFD model using Ansys For simplicity and validation purpose, the model defines fracture as an empty space between two circular disks. Moreover, it is considered that single phase fluid is flowing through fractures. By solving the flow equations in the model, correlations to determine the fracture width and invasion radius have been developed for specific mud rheological properties. Prior to onset of drilling and at the end of lost circulation, similar correlations can be developed by knowing rheological properties of drilling fluid which will be very much helpful to take an instantaneous action during lost circulation i.e. determining lost circulation material (LCM) particle size and also be useful in the well development stage to determine the damaged area to be treated.
 

Abstract
Produced water is water trapped in underground formations that is brought to the surface along with oil or gas. It is by far the largest volume byproduct or waste stream associated with oil and gas production. Produced water handling has been an issue of concern for oil and gas producers as it is one of the major factors that cause abandonment of the producing well. The development of effective produced water management strategies poses a big challenge to the oil and gas industry today. The conversion of produced water into irrigation or fresh water provides a cost-effective tool to handle excessive amounts of the produced water. There are more than 150 methods for produced water treatment. In this research, we proposed on-site produced water treatment units configured to achieve maximum processing throughput for Bangladesh. We tested the produced water sample collected from a Gas field in Bangladesh in BASF Bangladesh Ltd. construction chemical Lab. The lab test result showing that the Dissolved oil, EC, TDS, Na, CT, HCO, COD, Ca², and other parameters of produced water are much higher than the acceptable limit define by Environment and Forest Ministry of Bangladesh. We also studied various advanced separation techniques to remove oil and dissolved solids from the produced water. We selected media filtration as the oil removing technique and Reverse Osmosis (RO) as the dissolved solids removing technique along with three stage separators as being the best for Bangladesh based on produced water property.

The study results show that the media filtration remove more than 90% of the oil and grease and water recovery nearly 100%. The RO units remove more than 95% of total dissolved solids from the produced water and it is the most used technology in the world (> 60% of worldwide seawater desalination installed capacity). The proper integration and configuration of media filtration and RO units can provide up to 80% efficiency for a processing throughput of 6-8 gallons per minute of produced water.

Finally a water treatment system designed considering a gas field producing 600 bbl equals 95400 litters water per day. The system is flexible and can be modified for the applications such as rangeland restoration, reservoir recharge and agricultural use and household use.
 

Abstract
Bangladesh is aspiring to reach the middle-income country status by 2021 and a developed country by 2041 Industrialization and job creation are the key challenges for country's steady growth rate and development. For industrialization the country needs reliable and quality supply of energy at an affordable rate. Per capita consumption of commercial energy and electricity in Bangladesh is one of the lowest among the developing countries At present, around 90% of the people have access to electricity and per capita generation (including captive power) is only 464 kWh in Bangladesh. To achieve targeted GDP 587,665 million USD by 2041, country's total energy demand will be 130,827 ktoe. According to the Power System Master Plan, under long-term plan, there are targets of achieving electricity generation capacity of 24,000 MW by 2021, 40,000 MW by 2030 and 60,000 MW by 2041. At present, country's 63.31% electricity is generated by natural gas. Country's almost 68 percent of commercial energy is provided from indigenous natural gas By current statistics, country's remaining natural gas reserve is only 11.43 TCF at June 2018 and at current production rate it will be exhausted in the next 10 years. Country's gas demand has already surpassed about 3688 MMCFD whereas the average supply of gas is around 2663 MMCFD out of 2750 MMCFD capacity, leaving a shortfall of about 1025 MMCFD. Natural gas supply shortage against its demand constrains country's development. As for immediate remedy government of Bangladesh decided to import 500MMSCFD LNG and consequently signed agreement with Qatar's RasGas to supply 2.5 million mt/year of lean LNG for 15 years. According to the terminal use agreement (TUA), Excelerate Energy Bangladesh Ltd. (EBBL) have set an floating storage regasification unit (FSRU) at Moheshkhali for supplying 500 MMSCFD re- gasified LNG. RLNG is likely to be supplied to the gas grid. Bangladesh is searching for affordable energy sourcing options and planning for energy diversifications. To diversify the energy mix various conventional and non-conventional energy sourcing options need to be thoroughly examined.

The proposed project aims to evaluate LNG's prospects in power generation, industrial, transportation, commercial, and domestic sector with the consideration of cost effectiveness and environmental impacts compared to existing alternative fuels. The proposed project also aims to analyze the effect on consumer level gas price due to import of LNG and the minimum price for Government's no profit no subsidy position if the gas from LNG is mixed with the existing pipe line gas and LNG price adaptation in Bangladesh with respect to international fuel price

This study covers the latest energy sector scenario, LNG process chain, discussion of world LNG and other existing alternative fuels pricing system, forecasting consumer level cost and comparison among LNG and other existing alternative fuels at international market price.
 

Abstract
This project involves development of a remote monitoring and intelligent control (RMIC) of Cathodic Protection (CP) system of high pressure gas transmission pipelines operated by Gas Transmission Company Limited (GTCL).

The of the project was to design, develop, installation and testing of a remote monitoring and intelligent control system for CP. It would collect, transmit and interpret potential data coming from CP Stations along the pipeline in order to have a continuous monitoring and assessment of the system. In GTCL, traditional manual periodic monitoring system does not allow systematic continuous quality assessment of the pipelines; neither has it allowed real time reports. In addition, field inspections are costly, time consuming and required qualified personnel. The RMIC was developed integrating hardware, software and standard communication technology. This system is able to collect potential data from the CP station and transfer the data to the server. The software can interpret and analyze the data and also control the system remotely. CP station's voltage, current, and Drain point PSP (Pipe to Soil Potential) was collected and controlled using this system. The RMIC system was installed and tested at a CP station namely Dhanua of Dhanua- Savar Pipeline. For greater improvement and financial benefit this system should be introduced gradually at other CP Stations of the GTCL transmission pipeline grid.
 

Abstract
Sub-surface formations are always in a stressed state, mostly due to overburden and tectonic stresses. When an oil or gas well is drilled into a formation, stressed solid material is removed. The fluid pressure of the borehole supports the borehole wall. As this fluid pressure generally does not match with the in situ formation stresses, there will be stress redistribution around the wellbore. The new stress may be greater than the stress that the formation can support and subsequently failure may occur. Knowledge of the stresses around a well is therefore imperative to determine the wellbore stability and subsequently any potential risk of sand production.

Due to lack of proper knowledge for calculating Critical Drawdown Pressure and predicting sand production, some gas wells in Bangladesh have started producing sand. For the same reason, production rate from some gas wells have been kept limited assuming that sand production may trigger although the well formation has sufficient strength to prevent sand production.

The main objective of this project is to determine the Critical Drawdown Pressure of a gas well which is the maximum difference between reservoir pressure and bottom-hole flowing pressure that the formation can withstand without sand being produced along with the formation fluid.

Different existing Models have been used for this purpose and comparative analysis of those models have been performed. Based on this study, the Drucker-Prager model result meets and explain the current operating condition of the sample gas well. Hence with all its limitation, Drucker-Prager failure criterion has been considered a reliable criterion to predict sanding production when the well is in production.
 

Abstract
With rapid growth of national economy and strong social needs, energy has become an important strategic resource for national development. Although Bangladesh government is making great efforts to develop sustainable energy such as nuclear, coal mining, hydro power, wind and solar power etc, undoubtedly, petroleum and natural gas still dominate the national energy demands.

Although technological improvements have reduced Petroleum and other industry related deaths, accidents are still too common. That's why health, safety, and the environment culture remain among the top priorities for oil and gas industries, reflecting an attitude of zero tolerance for accidents.

Petroleum (Drilling) activities can take place in diverse geological and geophysical settings, each posing unique type of challenges. However proper planning, hazard control, inspection, incident investigation and reporting can reduces the number of accidents approximately to zero.

Health, Safety and Environment (HSE) should be the first priority in petroleum and mining industry for ensuring incident free operation with profitable growth in the business. Industry without practicing HSE (regulation) is very dangerous for personnel, equipment, material, property and environment. To ensure safety (incident free operation) regular inspection of project plant, rig site and necessary control measure should always be carried out by trained manpower, HSE personnel along with concerned special authorities to meet the demand of Occupational Safety and Health Administration (OSHA) standard and regulation (or OSH). Physical inspection, incident investigation and reporting, emergency planning, hazard identification, hazard control, Lockout/ Tag out (LOTO), Manual Materials Handling (MMH), hazard analysis, job safety analysis, risk analysis, stop work condition and authorities, training, employee orientation, tool safety, toolbox talk, are essential element for maintaining safety of industries. That's why this paper about safety culture has prepared by working on all of those.

Attitudes, personal education and experience, organizational training, communication mechanism and so on, all of them affect the development of a safety culture in any organization. The environment in which people work and the systems and processes in the industry also influence the safety culture. Therefore, each industry needs to consider all of these aspects in developing and nurturing a safety culture that suits the organization and the individuals within it.

In any Petroleum project, concern authority need to maintain standard quality of implementation of the HSE programmed with due consideration to standing Safety rules and regulations. The project may be considered viable from the Health, Safety and Environmental point of view and therefore be considered for implementation by appropriate authorities. It has been recommended that, Health, Safety and Environmental clearance would be issued in favor of petroleum project for execution of the project as incident free operation in future.

The research and conclusions and recommendations of this report could provide useful organizational safety culture concept to promote safety performance and safety management in Bangladesh.
 

Abstract
Demand of natural gas is always higher than the supply in Bangladesh. Correct estimation of reserve is important for the development of the gas fields, design of production facilities and preparation of the gas contracts. Narshingdi is one of the gas fields of Bangladesh Gas Field Company Limited (BGFCL). This field was discovered by Petrobangla in 1990. The objective of this study was to estimate the Gas Initially In Place (GIIP), remaining reserve, reservoir boundary, and various petrophysical data of Narshingdi gas field.

There are two gas sands, Upper Gas Sand (UGS) and Lower Gas Sand (LGS) in this field. Gas production started in 1996 and presently the two producing wells (NAR-1 and NAR-2) are producing gas from LGS at a rate of 17 and 11 MMSCFD respectively. Seventeen years of production data (1996 to 2013) have been analyzed to perform material balance and advanced decline curve analysis. Monte Carlo simulation approach was also performed to estimate proved, probable and possible reserve. Reservoir simulation using ECLIPSE 100. black oil simulator was performed for the purpose of history matching and production forecast. Different forecast scenarios were designed to investigate the effect of additional vertical well and gas compression on recovery.

The regular pressure survey of the field was not conducted and therefore Flowing Gas Material Balance an alternative to conventional material balance was performed. In the absence of pressure transient test (e.g., buildup, drawdown) data, advanced decline curve analysis was performed to calculate the reservoir potentiality (permeability, skin), reservoir area, GIIP and the ultimate recovery of the field.

This study shows that the reservoir is depletion type and the pressure decline is significant. Adding more well in the lower gas sand will not be beneficial.
 

Abstract
Permeability data from a reservoir can be obtained by various methods, namely: core analysis, well log data, Drill Stem Test (DST), and Wireline Formation Tester (WFT) or commonly called mini-DST. Both the core and DST methods require a large operating cost to obtain permeability data. This large cost results in the limitations of the use of core and DST methods in all reservoir zones in a well. Another method for obtaining permeability data is mini-DST. Mini-DST is a well test method like DST, but the operating costs of the mini-DST are much smaller, and the duration of the test from the mini-DST is much shorter. Mini-DST does not use DST, but uses Wireline Formation Tester (WFT) which is equipped with dual packer.

Permeability can be predicted by using core analysis, empirical methods from the data in the well log. This method uses the relationship between permeability to porosity and irreducible water saturation (Swirr) obtained from the well log [1,2]. Though DST is the most popular method, it is very expensive and time consuming.

The conventional WFT is currently only used to obtain the formation static pressure data, formation mobility, formation fluid identification, and formation fluid sampling By looking at the data build-up pressure during the data retrieval process at WFT, pressure build-up analysis can be carried out using pressure transient analysis (PTA) method using a Pressure Transient Analysis Software [3,4]. The data can be compared with the DST and core analysis data to validate and analyze the error with WFT data. The Error analysis of the data will be helpful to use formation tester data to predict permeability in the future development wells where the operator companies will be comfortable with only the WFT data for permeability.

Keywords: Permeability, mobility, Wireline formation tester, well log, DST, pressure transient analysis.
 

Abstract
With the rapid growth of technology the human world is becoming faster day by day. Database plays an important role for managing data with speed and accuracy in information technology. The aim of this project is to design a Gas Production Database to keep the gas production record of Bangladesh in an easy access form for authorised personnel only. This database will reduce the number of data entry errors in the Data Management Division of Petrobangla. Petrobangla is responsible for exploration and production of Natural Gas. Currently the Data Management Division uses Microsoft Excel to store and keep track of the natural gas production of Bangladesh. A Microsoft Access Database is designed to help minimize data entry errors and to make it easier to generate reports. A relational database is produced using Microsoft Access from this project work. Generation of gas production report on daily, monthly, yearly basis or for a specific time period, historical work over record according to well, chemical composition according to gas field, graphical presentation of production history such as FWHP vs time, Gp vs time, condensate vs time, water vs time for a time period or entire time period are the outcome of this project work.

Abstract
Casing while Drilling (CwD) is a process in which a well is drilled and cased simultaneously. This innovative technology has been successfully practiced for the past decade. However, narrow annuli often causes problems like packing or caving in the wellbore that may restrict the fluid flow and hole cleaning capacity. Hydraulic lift could be one of the beneficial factors that can be used to increase the efficiency of drilling as it can be used to monitor the wellbore condition. The purpose of this project work is to develop a theoretical model to calculate the overall hydraulic lift during CwD to evaluate the wellbore irregularities.

As CwD process utilizes large diameter casing to drill, several forces act upwards on the casing. Usually Small annulus brings about higher frictional pressure drop compare to the conventional operation that causes high upward drag force on casing wall. Another force acts upwards at the bottom face of the casing while fluid exits through the nozzles. In this study fluid hydraulic principles have been used to generate the overall hydraulic lift model. This theoretical model has then been compared with field measurement from hookload. Deviation of the field measured value from the predicted hydraulic lift is an indicator of wellbore conditions.

In this study trend of hydraulic lift predicted using theoretical model is compared with the field measured value of an well. Observation of this comparison is then analyzed with the field report to validate the model. Hydraulic lifts for three different depth interval and flow rates are measured. Findings of the comparisons are correlated with the summary of the field report for each section. Most significant finding is higher field measured hydraulic lift means higher friction due to packing or caving from the well bore that resembles the field observation also for a certain interval. The novelty of using hydraulic lift in CwD will enable the monitoring of wellbore condition to improve hole cleaning efficiency during operation.
 

Abstract
The natural gas transmission pipeline network in the Western Zone of Bangladesh currently comprises of 246 kilometer of pipeline. About 110-120 MMsefd of natural gas, which is 5% of the total production (2350 MMscfd), is supplied through this network. The Government has planned to supply gas to more areas in the north and south western regions of the country. About 177 kilometer of pipeline is already constructed for this purpose, which will be connected to the existing network in near future. Thus natural gas will be available to Kushtia, Jhenidah, Jessore and Khulna districts. Compressor stations are also being erected at Elenga, Tangail and Ashuganj, Brahmanbaria to boost up the pressure and throughput of gas through this network.

Detail study is needed on the west zone gas transmission network regarding pressure drop along the pipeline and availability of gas at various off-takes. Prediction of pressure drop along the pipeline in a network is very important as it indicates the pipeline efficiency, volumes available at various off-takes/outlets, maximum possible distance of transmission for a given upstream pressure, effect of compressors, etc. This kind of study requires numerical simulation with powerful computational resources.

This study presents some results from the simulation study of the west zone gas transmission network. A virtual model is constructed, which includes both the existing and new extensions to the network. The model is first validated by matching with the existing network using known data. Then simulation runs are performed to investigate the issues mentioned above. In addition, sensitivity studies are performed to investigate the effects of supply-demand fluctuations. Commercial software package PIPESIMTM is used for this work. The starting node of the network is at Elenga, Tangail. The existing pressure at this point is 400 psig. The fare most downstream point of the network is Khulna.

The study will improve operational standard consistent with the world gas industry which will be helpful for smooth operation of the network. The study will also be helpful for proper planning and design for augmentation of national gas grid for the uninterrupted transportation of natural gas in safe, reliable and economical way to the demand centers for ultimate distribution of the same.
 

Abstract
Bangladesh Oil Gas and Minerals Corporation short named Petrobangla operates oil and gas exploration, development, transmission, distribution and conversion together with development and marketing of in Bangladesh. Bangladesh gas sector started its journey in the 60s, but its rapid expansion and integration started to accelerate in the early 70s spurred by the rising of the oil prices. Till now, 24 gas fields have discovered. Total recoverable proven and probable gas reserve is about 26.84 TCF and recoverable reserve is 20.70 TCF. Up to June 2013 about 11.2 TCF gas has been produced, leaving only 9.5 TCF recoverable proved gas. On the other hand, up to June 2013 about 30.27 MMBBL condensate has been produced so far.

Refinery Limited (ERL) plays a vital role in supplying around 40% of the country's current petroleum products demand. ERL processes crude oil imported by BPC and delivers the finished petroleum products to the other subsidiaries of BPC for marketing and distribution. ERL also processes natural gas condensate as crude mix. Besides ERL, Petrobangla companies like SGFL and BGFCL are fractionating condensate into different products like motor spirit (MS), kerosene, diesel and octane. And also some private entrepreneurs are fractionating condensate into different products like MS, kerosene, diesel, SBPS and MTT. So, these fractionation plants producing different products and marketed by Bangladesh Petroleum Corporation (BPC) are playing a big role reducing import to meet the national demand of Bangladesh.

SGFL. installed a fractionation plant to fractionate condensate into MS, Kerosene at Haripur in 1960. At present there are twelve fractionation plants are in production a total capacity of 11,000 BBL/Day in Bangladesh. These fractionation plants both by government and private organization are contributing in the national economy reducing imports of finished petroleum products.
 

Abstract
Drilling activities can take place in diversified geological and geophysical settings, each posing unique type of challenge. There is no universal methodology to address all the situations. Therefore, each project is tailored on a case by case basis. However, it is possible to analyze the problems and to table the common items to bring them under a systematic procedure. Well site development is the initial stage of a drilling project. It involves mainly Civil Engineering works which includes earthworks, leveling, proper compaction, construction of rig and machinery foundation, well site yard, pipe rack, cat walk, mud pit, ware houses, deep water well with water line, office and personnel accommodation, security fencing/wall, sanitary and drainage works etc. An unplanned or faulty development of a drilling site may cause severe problems which may even jeopardize the entire drilling project.

State-run and international oil companies have so far drilled about 186 wells in different geographical and geological conditions of Bangladesh. Currently, BAPEX and 4 IOC's are the country's drilling activities. In onshore, the North-Eastern territory of the country has offered the most of the oil and gas resources. Besides, a number of wells have been drilled in off shore as well. Despite of having the drilling experiences, it is difficult to get a generalized idea on the drilling issues due to lack of compilation of the individual experiences.

In this study, the challenges and remedial measures of six representative well sites have been analyzed. This study took a closer look at the challenges and remedial measures of the sites as the first attempt of this kind in Bangladesh. It observed the nature of the problems and their reasons; degree of severity which causes time and cost overrun of a project. For example, the cost overrun comes from 5% to 44% and the time overrun comes from 0% to 83% in the same project due to the severity of the problems such as excessive rain, flood etc.

It is revealed that, heavy rainfall during the monsoon and consequent flooding poses the biggest and most common problems for the pre-construction activities before drilling wells. The case-studies showed that the natural constrains caused delay in project implementation, difficulty of logistic movement, raise security issues, damage to equipments and cost overrun. The terrains are either low lands with seasonal water bodies, popularly known as haors, or hilly areas with dense forest. Both types of lands are susceptible to flooding, landslide or washout.

Construction and maintaining of the approach road is the next biggest challenge, which is also tied to flooding and remoteness of the location. In some cases, scarcity of manpower and proximity to the international border are also problems. It is therefore important that the weather and flood pattern, availability of manpower and proximity to international border from locations should be taken into account to plan the logistic movement.
 

Abstract
Estimating reservoir properties has long been a challenge. Traditionally, pressure survey or well testing is conducted to estimate the reservoir properties, which is expensive; also production loss is associated with pressure survey. The importance of performing accurate analysis and interpretation of reservoir behavior using only rate and pressure data as a function of time is fundamental to assessing reservoir properties such as permeability, skin and reservoir drainage area.
The equations used for well test analysis are derived from the constant terminal rate solution of the radial diffusivity equation (RDE). Conventional Decline Curve Analysis normally used to estimate original gas in place and gas reserves. The development of modern Decline Curve Analysis began in 1944. This technique used to analyze and interpret production data and pressure data from gas wells using Type Curves. This technique is also used to estimate Skin Factor for near wellbore drainage area, Formation Permeability, Reservoir Drainage Area and gas in place. As opposed to well test analysis, the equations used for modern decline analysis attempt to plot rate versus time with different transformations.
Therefore theoretically these two independent methods should yield same results. It is of interest to investigate whether in real case two opposite approaches can be used to obtain sufficiently close results of the same properties such as skin, permeability etc.
In this study two real cases were analyzed using both well testing and decline analysis. Commercial software Ecrin v4.20 (Saphir and Topaze) was used to carry out this work. It is found that the data quality is the greatest challenge with well testing data is obtained from a relatively short period of time in a controlled environment. If properly done, the data quality is good and results obtained can be reliable. However well testing is done only occasionally in Bangladesh, then developing a good understanding of the reservoir from well testing alone is often difficult. On the other hand decline analysis uses well pressure and production data which is usually available for the entire operational life of a well. Despite the volume of the data it is usually full of noise and difficult to discern the true reservoir signal from the dataset. However, sufficiently close results were obtained from the two approaches.
For Well # 4, k was 19.4 from DCA and 25.1 from PBU respectively; S was 0.996 for DCA and 0.64 for PBU. For well A#3, k was 52.53 from DCA and 83 from PBU respectively, S was 1.504 for DCA and 2.97 for PBU.
For DCA, two separate techniques (Fetkovich and Blasingame) were applied. They also showed reasonably close estimate of k (15.8 and 18.9) respectably and STGIIP (82.7 and 76.4 bsef).
 

Abstract
For any Environmental Impact Assessment (EIA), Initial Environmental Examination (IEE) is the prerequisite condition. If it suggests furthering clear assessment then EIA is must for that case. The IEE & ELA are the requirements of Department of Environment (DOE) for issuing the site clearance and environmental clearance respectively for the project. For any red category project EIA is mandatory. This ELA report has been prepared as per Terms of Reference (TOR) and the guidelines of DOE for exploratory well drilling project at the newly discovered Sunetra Structure.

In general, Drilling has temporary environmental impact compared to that of the other industrial projects. Among other topics, identification of potential impacts with mitigation measures, and an Environment Management Plan is included may be achieved through use of best management practices as well as mitigation procedures and controls which will have minimum adverse impacts on the environment. This project is focusing on the real condition of the area, the people who will be affected and how the mitigation measures should be applied. It is also disseminating the findings from public consultations, expectations of the people, economic development and potential negative impacts etc. This EIA report is introducing the natural physical resources available in the project area, present status and location, project components and phase etc. EIA report is also suggesting the Emergency Response and Disaster Management Plan, Environment Safety Management System Process, Health, Environment and Safety Management Plan, Environmental Monitoring parameters measurement cost etc.

Reconnaissance and follow-up site visits were made and information was collected on baseline conditions and the stakeholders' response on preset questionnaires/ checklist as per DOE guideline. Public awareness campaign was also made through key informant interview. Other environmental and socio-economic, agro-climatic and meteorological data were collected from DOE and concerned authorities and other IEE & ELA reports of relevance.

It can be said that the drilling project will maintain standard quality of implementation of the programmed with due consideration to standing rules and regulations. The project may be considered viable from the environmental point of view and therefore be considered for implementation by appropriate authorities. It has been recommended that, environmental clearance may be issued in favor of Sunetra Structure for execution of the project as scheduled.
 

Abstract
The Bibiyana gas field is the second largest gas field in Bangladesh, it has started its production on March 2007. Now it is producing about 840 MMSCF Gas and 3500 bbls condensate each day from 12 producing wells. All producing wells are located in two regions, such as North Pad and South Pad. In south pad 5 wells and gas processing facilities are situated and in North pad remaining 7 wells are located and connected to south pad process plant via common production Each well of North pad are comprised of individual Multiphase Flow Meter instead of conventional Test Separator Bibiyana Gas Filed first introduced this type of flow meter in Bangladesh to achieve better surveillance of reservoir and to apply better production allocation. Due to wrong selection of meter, fluid flow regime mismatch and due to lack of proper fluid sampling procedure this multiphase flow meter performance may also hamper. As per manufacturers' information, this flow meters accuracy is within ±5%, while in practice it is found that this error is about 6-9%. This project work determines the fluid flow profile by using Taitel-Dukler Model, investigates the working principle of this flow meter and their sampling and calibration technique. This flow meter measures gas flow rate by using v-cone differential pressure formula, water detection by microwave technology and hydrocarbon part is analyzed by PVT Software. As per equipment data sheet, it is found that this flow meter works well for Oil density 43.5-45.1 lb/ft and gas density 1.15-4.46 lb/ft while calculated value is approximately 47.8 lb/ft for oil and 0.05 lb/ft for gases. To find out the causes, this study investigates for any phase changes from well head to separator and found no phase changes occur in individual flow line for different flow rates. All calculation including fluid pattern are done manually and phase changes are investigated by HYSYS Model. Later flow accuracy is done manually by using Field Data of the Bibiyana Gas Field. This project also analyzes the applicability and selection criteria of Multiphase Flow Meter in Bangladesh in respect to installation cost, maintenance cost, fluid property, type of meter and calibration technique. Finally this study suggests that the existing technology can be used for process parameters monitoring within limited uncertainties and not suitable for custody transfer metering.

Abstract
To reach a decision as how best to produce a given reservoir it is essential to know its deliverability, properties, size and initial gas in place (GIIP). Estimating reservoir properties has long been a challenge. Traditionally pressure survey or well testing is conducted to estimate the reservoir properties, which is expensive; also production loss is associated with pressure survey. The equations used for well test analysis are derived from the constant terminal rate solution of the radial diffusivity equation.

Well testing data is obtained from a relatively short period of time with a controlled environment. If properly done, the data quality is good and results obtained from this test can be reliable. This technique is used to estimate Skin Factor, Formation Permeability, Reservoir Drainage Area, Average reservoir pressure, distance to faults, Connectivity among well etc. If well testing is done only occasionally, developing a good understanding of the reservoir from well testing alone is often difficult.

Conventional Decline Curve Analysis normally used to estimate original gas in place and gas reserves. The development of modern Decline Curve Analysis began in 1944. This technique used to analyze and interpret production data and pressure data from wells using Type Curves. This technique also can estimate skin, permeability and gas in place. But most of the time it is impossible to maintain controlled condition to collect undisturbed data of decline curve analysis for a long period of time like short period of time of well testing data.

In this study for a well evaluation real cases was analyzed using both well testing and decline analysis. First Skin and Permeability are determined with the help of pseudo pressure versus Horner time. Also non-Darcy flow coefficient is determined from deliverability test equation. This Skin, Permeability and non-Darcy flow coefficient is a reference point to model a reservoir. Classical material balance and its output GIIP is also another reference point to model a reservoir for modern Decline Curve analysis method
The GIIP estimated from classical and flowing material balance methods are 600 BCF and 580 BCF respectively. The same is estimated to be 629 BCF by Fetkovich, 630 BCF by Blassingame and 473 BCF by Arp's method. Except for Arp's the rest of the methods
provided reasonably close results. The skin factor estimated from well testing analysis is in good agreement with Decline analysis result. Skin, s from Horner plot is 21.15, from type curve is 20, Fetkovich type curve is 19, and Blassingame is also 19. Rate dependent skin is also detected during well test analysis, which was characterized by non-Darcy flow coefficient of 0.456 [MMscf/D]'. Skin value is quite high, the major contribution is due to formation damage (s-13) and the partial completion is not significant (sp-2.15). The permeability estimated from well testing is good agreement with past studies. Permeability, k from Homer plot is 201.6 mD and type curve is 236 mD. k was also estimated decline analysis method. Both Fetkovich and Blassingame methods provide 'k'  value close to each other but order of magnitude lower than well testing results.
 

Abstract
The Bibiyana gas field is one of the most prolific gas fields in Bangladesh. It stared production in March, 2007 with 200 MMSCFD. Production has steadily increased from this field, and currently it is producing more than 730 MMSCFD. In addition, Bibiyana field also produces about 3,500 barrels of condensate per day. There are six storage tanks for condensate final stabilization and storage. Significant amount of vapor is produced in these tanks due to shrinkage/flash, standing and working effects. This vapor is hydrocarbon, i.e., natural gas, which has heating value and therefore valuable. There is a three-stage vapor recovery system in the field to capture the vapor produced at different stages of production and processing. However, vapor from the storage tanks cannot be recovered by the existing system because its pressure is too low- nearly atmospheric. It is regularly flared through the Low Pressure Flare line. Flaring of gas is a problem which entails both economical loss and environmental concerns. The hydrocarbon burning produces toxic gases, soot, acid rain, unburned hydrocarbons and a huge of CO₂, which contributes to greenhouse effect. The economical impact is the cost of gas that is flared.

This project demonstrates a method for recovering the low pressure vapor from the condensate tanks. This method uses a Gas ejector as a device to compress the low pressure natural gas from the condensate tanks to an intermediate pressure, which can be fed into the intermediated stage  of the existing vapor recovery unit. Thus the natural gas will be saved which would have been otherwise flared. The amount of tank vapor is calculated by different methods, which shows a significant amount of gas which is now being flared. Gas ejector is a device which converts pressure energy of a motive stream into kinetic energy which entrains a secondary stream and discharges the combined stream at an intermediate pressure. This project uses the relatively high pressure gas from the third stage of the existing vapor recovery unit as the motive gas, and the low pressure condensate tank vapor as the suction gas for ejector. The combined discharge stream will be fed into the vapor recovery unit's second stage.

Gas ejector has no moving parts. It involves almost maintenance free operation and no operating cost. It has been demonstrated as a viable technology for recovering condensate tank vapors in different fields in the world. This project describes the system design with the ejector technology, estimation of tank vapor recovered, and economical and environmental benefits. It is estimated that, on average 190 MSCFD tank vapor can be recovered. This should result in to yearly saving of about 68 MMSCF of natural gas. The equivalent to heat energy saving is about BTU. The simple payback period of this project covers in 7 months.
 

Abstract
The world needs energy- and over the short and medium term it is clear that much of our global energy consumption will come from fossil sources such as oil, gas and coal. With the current growing demand for oil led by major energy consuming countries such as China and India, securing new oil resources is a critical challenge for the oil industry. Each year, new production is needed to compensate the natural decline of existing wells, and the additional production required to satisfy the yearly demand for hydrocarbon energy that will represent approximately 9% of the worldwide total production. For this growth to be sustainable, a strong focus will have to be placed on finding new discoveries and/or optimizing oil production from current resources. The cost associated with the first option is significant. Therefore, reservoir management teams all over the world will have to cater for this demand mainly by maximizing hydrocarbon recovery factors through Enhanced Oil Recovery (EOR) processes. EOR consists of methods aimed at increasing ultimate oil recovery by injecting appropriate agents not normally present in the reservoir, such as chemicals, solvents, oxidizers and heat carriers in order to induce new mechanisms for displacing oil.

Chemical flooding is one of the most promising and broadly applied EOR processes which have enjoyed significant research and pilot testing during the 1980s with a significant revival in recent years. However, its commercial implementation has been facing several technical, operational and economic challenges. Chemical flooding is further subdivided into polymer flooding, surfactant flooding, alkaline flooding, miscellar flooding, alkaline-surfactant-polymer (ASP) flooding. ASP flooding is a form of chemical enhanced oil recovery (EOR) that can allow operators to extend reservoir pool life and extract incremental reserves currently inaccessible by conventional EOR techniques such as waterflooding. Three chemical inject in the ASP process which is synergistic

In the ASP process, Surfactants are chemicals that used to reduce the interfacial tension between the involved fluids, making the immobile oil mobile. Alkali reduces adsorption of the surfactant on the rock surfaces and reacts with acids in the oil to create natural surfactant. Polymer improves the sweep efficiency.

By simulating ASP flooding for several cases, with different chemical concentrations. injection length, time of injection, current well optimization and new well placement, this report suggests a number of good alternatives. Simulations showed that the most effective method was not the most profitable.

From the simulation results and economic analysis, ASP flooding can be a good alternative for the Norne E-segment. But the margins are not significant, so fixed costs (such as equipment rental) will be of crucial importance.
 

Abstract
The main objective of this field is to investigate various optimum field production strategies of the whole production system (from reservoir to separator) of Narsingdi Gas Field, Bangladesh using The Integrated Production Modeling. IPM suite (GAP, PROSPER, MBAL) software package by applying the trademarked methodology of Nodal Analysis. Recommending the best optimum production strategy on the context of recent gas crisis in the Bangladesh is the ultimate goal of this investigation.

Individual modeling (Pressure and Temperature) of the wells in PROSPER by Nodal Analysis is a prime requirement of this work. Another important pre-requisites are to estimate the reserve of the field by Material Balance Method in MBAL, quality check with the recent volumetric reserve estimate, proper aquifer modeling and determine missing reservoir/aquifer parameters of the field. Based on this reserve estimation, various production forecasting and reservoir performance for existing and optimum conditions had been investigated after the whole production system of reservoir, wells, pipelines, chokes and separators in the GAP model.

The reserve of the lower gas sand of this field is estimated to be 273.838 BCF which fairly agrees with the recent estimate of 284 BCF. During the prediction run for various existing and optimum production strategies, it had been found that acceleration of production for existing conditions does not improve the gas recovery in a great deal, but when the wellhead backpressure is reduced by installing surface compressors and knockout drum, it definitely improves the gas recovery factor by 23%. Finally, an optimum production strategy is recommended along with future installation of surface compressor and upgrading of gas processing capacity.
 

Abstract
BAPEX operated Fenchuganj Gas Field, 40 kilometer south of Sylhet in Bangladesh, lies in the south central part of Surma basin. A second well FG-2 was spud on January 1985 after the first well drilled in 1960 was abandoned as dry hole. Three gas sands (Upper, Middle & Lower) were tested and completed the well at upper gas sand in 1988. Gas production from the well started on May 2004. Next a development well, FG-3 was drilled by BAPEX in 2004 and gas production started from January 2005. Gas production from upper gas sand of FG-2 was suspended after extracting 24 BSCF gas due to excessive sand and water production. Later the well was re-completed at lower zone and due to the same reason production rate was lowered. Therefore, future field development plans as well as diagnosis the reason of water break through of the well needs to be investigated.

Despite of volumetric analysis, under the project RMP-2 of Petrobangla in 2009, RPS Energy prepared dynamic reservoir simulation model of Fenchuganj Gas Field. In this current study, the geological model was revised by correlating with seismic and log data and imporated in a commercial 3D black oil reservoir simulator ECLIPSEM 100 to construct a dynamic reservoir simulation model. Later the dynamic simulation model was validated by using historical pressure and rate data in history matching phase. Finally, the history match model was run for five different forecast cases to find out a better field development plan.

Forecast Case 5 of the current study yield 81.75% gas recovery out of 386.05 BSCF estimated GIIP after 25 years of prediction period by drilling additional three wells as well as workover of the existing wells. Aquifer support is identified in the upper gas sand during history matching as well as water break through in FG-2 has been investigated.
 

Abstract
Borehole instabilities during drilling are more common in shale formations than in most other rock formations. Shale make up more than 80% of sediments and rocks in siliciclastic environments and about three quarters of borehole problems are caused by shale instability. The assessment of in-situ stress and analysis of borehole failure due to instability and weak bedding plane represents one of the most critical factors when evaluating borehole stability that causes borehole failure. Significant amount of research have been done in this area which resulted in various mathematical models about the issue of borehole failure, stability and plane of weakness due to bedding. Especially Aadnoy, Chenevert, Jaeger and Zoback showed that at a certain angle rock failed at a very low load condition. Several material constitutive models have been considered for rock failure studies, including the Mohr-Coulomb, the Mogi-Coulomb, the Mohr-Coulomb elasto-plastic, Dracker-Prager, and the modified Lade models by all researchers. Shale instability is an extremely unpredictable and potentially costly problem in many foothill drilling operations still now. So far, unified decision about the plane of weakness and failure of borehole on shale is yet to be fully realized by the industry.

This paper analyzed the bedding plane failure and reproduced some of the results published in literature. This works studied based on the Aadnoy et.al. (2009) paper's field data and reproduced their combination of parameters that create bedding exposed positions. This thesis paper is based on a linear clastic and isotropic model for stresses around the wellbore, with the aim of trying to understand the general behavior of inclined boreholes due to anisotropy. It was found that borehole collapse was caused predominantly mainly by shear but also by tensile failure. The analysis remarkably found that for a laminated rock, a weakness of a plane may subject the well toward collapse for the hole angles between 10 to 40° (Aadnoy and Chenevert 1987).

This paper analyzed the 3D effect of attack angle with changing azimuth for a constant inclination on bedding plane. It is seen that bedding exposed is not only depends on inclination but also depends on dip of the formation, attack angle and azimuth. This paper also made a model which is enhanced Aadnoy et.al. (2009) model so that users can get the optimized well path and can make sure whether their well data has existed on the bedding exposed or protected positions. This thesis has tried to focus on mechanical wellbore stability and plane of weakness of shale formation and analyzed the Aadnoy et.al (2009) models to address the existing problem on this matter.
 

Abstract
The Bakhrabad-Chittagong (BKB-CHT) high pressure gas transmission line was first commissioned in 1983. It is a 175 km long, 24" dia. 960 psig) gas pipeline which was built to supply gas from the Bakhrabad Gas field, Muradnagar, Commilla to Chittagong City Gate Station (CGS). Faujderhat, Chittagong. Gas is being supplied to the consumer of Commilla, Chandpur. Lakhsum, Feni, Maizde, Choumuhoni, Laksmipur, Chittagong as well as the huge area of the South-East part of Bangladesh by the different off-takes along the pipeline.

On stream pigging operation was first accomplished to BKB-CHT pipeline in July, 1990 and second time it was done in February, 1994, Significant amount of condensate, sludge and water were recovered from this pipeline during these operations. After thirteen years, on stream pigging operation to BKB-CHT pipeline was done during 12 -13 November, 2007 by Gas Transmission Company Ltd (GTCL). The anticipated amount of condensate, sludge etc. were not recovered from this pipeline during the latest pigging operation. It is therefore necessary to analyse the latest pigging operation to understand the effectiveness, and to find out the reasons for such large differences of the outcomes compared to the previous operations.

The reveals that in the beginning years the gas processing at Bakhrabad Gas Field was inadequate. The pipeline was not being used at its full capacity. Due to reasons, was scope for accumulation of large amount of condensate. Therefore during the first and second pigging operations, large amounts of condensate were recovered (7.11,000 and 3,87,000 litres respectively). The third (3) pigging operation however did not yield the anticipated quantities. The probable reasons are:

●    After the second pigging operation, BKB Gas Field Process Plant are being operated in sufficient capacity.

●    In 1997, Ashuganj- Bakhrabad 30" pipeline was commissioned. So since 1997,BKB-CHT pipeline have been being operated in actual capacity range.

●    Since 1997, most of the gas feed to BKB-CHT pipeline was from AB pipeline and this gas was coming from other gas fields such as Titas, Habiganj, Rashidpur, Kailashtila and Jalabad Gas Field. Thus gas from these sources are already processed at origin. Moreover, some liquid is recovered at the Ashuganj Menifold Station. Therefore when the total mix of gas is fed onto BKB-CHT pipeline it is almost dry.

●    After the second pigging operation, BKB Gas Field, Salda Gas Field and Meghna Gas Field have been supplying dry gas. 
●    Sufficient capacity heater are being used at ICS Feni and CGS Faujderhat after second pigging operation.

●    During the year 2005-2006, average 3000 gallons/month of condensate were collected at CGS Faujderhat and average 1000 gallons/month of condensate were collected at ICS feni. Therefore it is possible that whatever amount of condensate accumulated in the pipeline were removed during this period.

●    Since 1997, average 225-250 mmscfd gas was supplied through the BKB-CHT pipeline. So condensate and Sludge could not accumulate inside the pipeline and were collected at ICS feni and CGS Faujderhat. So almost all the condensate were collected after the second pigging operation.

Abstract
Bangladesh is a South-East Asian country with a booming economy. From the late eighty's of the last century, industrialization have been flourished with supply of natural gas. Natural gas is the major energy source of Bangladesh. At present, country's gas demand is around 2300 MMSCFD, but production against this demand hovering at 2000 MMSCFD. To meet the rising demand of natural gas, Petrobangla, which is assigned for energy related activities, is trying to find out new reserves and also taking initiatives to augment gas supply from the existing gas fields on operation. Currently 18 number of gas fields is producing from 79 wells.

Among the gas fields, Habiganj is the only bottom water reservoir. The water table is moving up gradually with production. The Habiganj Field is an elongate asymmetrical anticline with a simple four way dip closure. Eleven wells have been drilled so far and two of them already been shut-in due to high water cut. The reservoir succession is divided into three sand layers: the upper gas sand (UGS), and two lower gas sands (LGS 1 and LGS 2). The UGS is the most prolific, which constitutes the major producing zone in this reservoir. In this report, we tried to evaluate water coning problems in Habiganj Gas Field and calculated critical rate and breakthrough time by using different empirical relationship. Critical rate is defined as the maximum amount of production rate above which the flowing pressure gradient at the well causes water to cone into the well and if a well produces above its critical rate, the time required to water breakthrough into the well is called breakthrough time. These two parameters are very important for proper well management, which is definitely related to economical considerations also. Premature cone breakthrough into the well will reduce the overall recovery of the reservoir and also the efficiency of the depletion mechanism as well. Some remedial measures have been suggested in this report to mitigate coning.

Abstract
Well testing provides reliable information about the reservoir and the producing wells that produce from that reservoir. Main reservoir parameters, total permeability-thickness product, kh (md. ft), average permeability, K (md) and initial reservoir pressure, Pi (Psia), and well parameters such as wellborstorage coefficient. C (bbl/psi) and skin, S, are estimated in this project work by using well testing software package (Well Test by Fekete associates Inc.).

Data were collected from 8 (eight) wells, 3 (three) of Kailastilla Gas Field, 2 (two) of Biany Bazar Gas Field, 3 (three) of Rasidpur Gas Field, operating under Sylhet Gas Field Limited (SGFL), a company of Petrobangla. Same data are analyzed by Almansoori Wireline Services, a third party welltesting service provider. Intercomp-kanata Management Ltd. (IKM), Oil & Gas Field Exploration Services Company, also determined these reservoir and well parameters under a contract with Petrobangla. The results of the analysis of this project work. AL Mansoori Wireline Services and IKM are shown in a table at the end of the diagnosis of each well.

The synthetic pressure and pressure derivative data match with actual pressure and pressure derivative plots, Absolute Open Flow (AOF), coefficient, C, and exponent, n, of the deliverability equation are estimated through this thesis work. The main parameters average permeability, K (md), and skin, S, for KTL#1, KTL#2, KTL#4, BB#1, BB#2, R#1, R#4 and R#7 are 134 and 2.4, 5575 and 4.1, 238 and 9.8, 213 and 17.1, 95.6 and 13.8, 2150 and 7.2, 16 and -4.8, 20.8 and -0.70 respectively. However, from core data analysis; Average Permeability of the Middle Gas Sand, producing zone of KTL#1 and KTL#4, of Kailastilla Gas Field is 88.4 md, and 424.3 md for the Upper Gas Sand, producing zone of KTL#2, of Kailastilla Gas Field, Average Permeability of the Lower Gas Sand, producing zone of BB#1, of Biany Bazar Gas Field is 189.6 md, and 332.4 md for the Upper Gas Sand, producing zone of BB#2, of Biany Bazar Gas Field, and Average Permeability of the Upper Gas Sand, producing zone of R#1. R#4 and R#7, of Rasidpur Gas Field is 370.0 md.
 

Abstract
Our country cannot be developed without any natural resources and energy. In our country natural gas is the primary source of energy. So proper utilization of our natural gas can play vital role and bring economic prosperity. Proper use of natural gas is the vital interface between the gas distribution companies and the end users. So, proper distribution and utilization of natural gas is the key point of our economy. The economic improvement of our country is hampered by the phenomenon called gas system loss. In all categories of gas consumption there is system loss. Especially in domestic sector where the system loss is a great suffering to the customers.

One of the remedies to reduce domestic system loss suggested by many is to introduce meters. Installation and maintenance of meter system is very expensive. Although large scale system loss is attributed to domestic sector, no clear usage data is available to support that accusation. A study to actually measure the monthly gas use in an average house hold and an estimate of wastage is essential before any decision on metering can be taken. The study finds that gas wastage in domestic sector is actually much less than generally perceived. Financial investment of metering system and possible alternate options are discussed.
 

Abstract
This thesis paper depicts the development of an integrated production network model for a producing gas field (Rashidpur Gas Field) in the eastern part of Bangladesh. Integrated production modelling is a powerful method for optimizing the gas field production planning and extenuating the risk. This approach combines the reservoir performance, well inflow and outflow and surface facilities in a single platform to cover all operating envelopes and constrains. Once the model is established, the representative system production forecasts can be generated to study alternative development scenarios against reservoir performances. This allows choosing an optimum production strategy from different alternate situations. This method is computationally intensive, therefore commercial software packages are used to conduct this study. PROSPER, MBAL and GAP tools from the IPM software suite were used to carry out the thesis work.

The whole effort can be divided into three sections. First, all wells are modeled by PROSPER where wells inflow performance relationship and vertical lift performances are calculated. The second task is to estimate the reserves by material balance method using the MBAL tool. Finally GAP tool was used to incorporate all the information obtained from MBAL and PROSPER to run predictions based on different production scenarios.

The Rashidpur Gas Field has two producing zones named as Upper Gas Sand (UGS) and Lower Gas Sand (LGS). In 1990, volumetrically estimated reserve found 0.48 Tef and 0.634 Tef for Upper Gas Sand and Lower Gas Sand respectively. After 17 years of production, this study estimates the new reserves of 0.54 Tef and 1.26 Tef for UGS and LGS respectively by Material Balance Method. This study identified a very weak radial aquifer support for the Upper Gas Sand.

The current production strategies have recovery factor of 49.38 % and 40.46% only for next 25 years. An attempt to increase production from this field has been considered in this study since the field is producing only 50 MMScfd having installed process plant capacity of 220 MMScfd.
 

Abstract
Well-7 of Haripur gas field was spud in 1986 by BAPEX. After 07 years of uninterrupted oil production, the well ceased its production on 14th July, 1994. The 1" work over of Sylhet well -7 was completed in March 2005. This well was recompleted in lower Bokabil sand as gas producer with an initial production capacity of 15MMCFD. The gas production was ceased again in July 2008. The 2nd work over has been successfully completed in the existing perforation zone on February 2, 2010. Commercial gas production started from Sylhet-7 with an average production 6-8 MMSCFD with about 2100 psig well head pressure.

In this study, material balance, production data analysis (PDA), pressure transient analysis (PTA) and reservoir simulation are conducted to understand the different reservoir information and predict future production performance.

This study uses Material balance analysis tool MBAL, Well model software PROSPER, PDA too! TOPAZE, PTA tool SAPHIRE and commercial reservoir simulator CHEARS to find out reservoir characteristics, pressure and production history matching of producing sand of Haripur gas field.

This study estimates initial gas in place, recoverable reserves and remaining reserves of producing sand of Haripur gas field. Current study has yielded the gas initial in place of 24 BSCF of lower Bokabil (sand-D) sand which is close to Petrobangla recent study by RPS Energy. Permeability and skin factor of this formation are investigated by pressure transient analysis. No re-estimation of reserve for the other sands is conducted in this study.
 

Abstract

In Titas gas system Orifice and Turbine meters are most widely used for gas flow measurements in bulk customer's RMS, CGS, TBS and DRS. Generally at the purchase points, Orifice meters are used in gas delivery line. The total gas input measurement that made by production companies depend on Orifice meters reading. About 1300MMSCFD gas is purchased from the production companies and delivered to the customer end through the Orifice and Turbine meters in Titas franchise area, so it is apparent that accurate measurement is very important for companies.

This project aims to perform a comparative study on measuring principle, measuring devices, Operation & installation standards, metering accuracy and uncertainty analysis of Orifice & Turbine meters. As Titas Gas Company has to procure and install a large number of meters for gas flow measurement for various load applications and operating conditions, therefore, selection of meters for various types of customers is one of the major objectives.

In this project Calibration method of Orifice meter with secondary devices have been studied and analyzed the calibration results to determine what affect the accuracy of gas flow measurement. For an Orifice meter due to differential pressure measurement deviation, it has been found that 4.7% flow measurement error occurs at minimum flow rate and 1.5-2.0% error occurred in normal operating range (range of customer demand). Similarly, from the test results of Turbine meters, it has been observed that Turbine meters with higher capacities, show below 0.5% error and Turbine meters with lower ranges perform below 1% error with respect to reference/standard meter.

Analyzing the uncertainty of Orifice meter with 0.71439 beta ratio, 1.06% measurement uncertainty have been found. For Turbine meter the measurement uncertainty value is 0.68%. If two Orifice meters are installed in series in Titas Gas Transmission system for counter measurement, a significant flow difference have been found in gas flow measurement by two Orifice meters. The comparison of flow measurement between Orifice and Turbine meters have been made by considering measured variables data over 15 months when the two meters installed in series. From that analysis, it shows that Turbine meter measurement is 1.992% better than that of Orifice meter with considering calibration and uncertainty analysis.
 

Abstract
Model production sharing contract (MPSC)-2008 has been formulated with a view to meeting the present and future energy demand. The comparative study of MPSC- 2008 with some regional countries would answer some of the questions recently.

In Bangladesh, natural gas is the only significant source of commercial energy, and accounts for almost 75% of total commercial energy consumption. Current gas supply capacity is 1,950 mmcfd, whereas demand is about 2200 mmefd. There is large gap between demand and supply in Bangladesh and it is increasing everyday. The country has no alternative but to explore new gas fields to overcome the gas shortage that has already started. Bangladesh has explored some major gas fields in onshore but the offshore is unexplored yet. For uninterrupted gas supply to the existing customers and to meet the anticipated demand, the model PSC-2008 has been formulated.

To ensure the accountability, transparency and public participation in decision making process, the Government of Bangladesh published the contract document through website at an early time.

There are some confusion regarding this contract for which a thorough comparative study is required. In addition, an overall review was required to understand and evaluate the pros and cons of the contract and to verify whether the people's interest is properly reserved or not.

Based on different aspects the Contract has been compared and examined. To do this comparison some regional countries like India, Malaysia, Pakistan, Vietnam, Turkmenistan and Trinidad & Tobago are chosen. All the countries except Trinidad & Tobago are regional countries. The reason for selecting Trinidad & Tobago is that it is also a developing country like Bangladesh but it is near to USA and has a large petroleum market.

In conclusion, the overall contract was found to be balanced and very much comparable to the regional countries. Moreover, it has conceived important improvement as compared to Model PSC-1997 and other signed blocks by accommodating the experience of these contracts
 

Abstract
In gas transmission and distribution system, the gas pressure and flow rate are controlled by using CGS, TBS, DRS and RMS. It is important to supply uninterrupted gas at a desired pressure and flow rate to the customer premises. The Regulating and Metering Station (RMS) is generally used for controlling the gas pressure and measuring the gas volume for fiscal purpose. It is apparent that proper design of RMS is very important for a customer for supplying desired amount of gas at a required pressure as well as measuring the supplied gas accurately which is very much crucial for gas supplier in fiscal context. A large number of RMS's are used for gas supply to different customers in the Titas franchise area.

The major objective of this project is to design an ideal gas Regulating and Metering Station for uninterrupted gas supply to a 50 MW power plant. In this project work, fluid characteristics, process data, gas safety rules, International codes and standards (ASTM, ASME ANSI, API) have been followed for the proposed RMS design. Design considerations, selection criteria and installation of RMS equipments are incorporated. Safety and Environmental issues have been considered in designing the gas facilities for the power plant. The negative effects on environment are negligible. The gas load of the power plant is calculated around 12 MMSCFD at minimum outlet pressure of 50 psig. Design has been checked allowing variation of some related variables such as inlet pressure, specific density, specific heat, compressibility factor and heating value. Variations of these parameters need no change in the design. Instrumentation and piping diagrams of the proposed RMS are also shown in the report. Some recommendations have been made for improvement of the RMS design. Finally, cost estimation is performed for the project.

The cost estimation of the project have been calculated on the basis of preconstruction expenditure, construction cost and material cost. The total cost of the project is estimated as Tk. 494.463 Lakh.

Abstract
Bangladesh Government has taken a new gas distribution pipeline project titled as "16 DN 140 Psig 100 Km Gas pipeline network within and around Dhaka City under Dhaka Clean Fuel Project" with the financial assistance of Asian Development Bank (ADB). This project is taken up because existing gas pipelines network of Dhaka City is inadequate to cater the present demand of gas for proposed CNG filling stations. The other goal of the project is to meet future demand of the city dwellers.

Government of Bangladesh has implemented the project through Titas Gas Transmission & Distribution Co. Ltd. (TGTDCL), a company of Petrobangla. According to the ECA 1995 (with amendment 2000) and the ECR 1997, TGTDCL has received environment clearance from the Department of Environment (DOE) for this Pipeline Project. PP(Project Proforma) of the project was approved on 10th June, 2003. The time limit of the completion of the project was June, 2007. The project was completed on June, 2008. This post estimated Environment Impact Assessment Study (EIA) has been carried out to identify all positive and negative impacts due to the pipeline project.

The consultants appointed by Titas Gas T & D Co. Ltd. expected in their Environmental Impact Assessment that some negative impacts would arise during pre-construction and construction periods of the project. But they suggested some mitigation measures that would minimize the predicted impacts. In view of my studies, from data analysis and site visit, it is found that proper mitigation measures were carried out against negative impacts during pre-construction and construction phase. Existing flora, funa, population, homestead and assets are not affected by implementation of this project. Therefore, no adverse impact on the environment is involved.
 

Abstract
Gas is the most valuable natural resource of Bangladesh. Estimating and updating the gas reserve helps the planners for drawing mid and long-term development plan from field development level to national level. So estimating correct reserve has become vital issue now a days. This report presents the study of reserve estimation of Narshingdi Gas Field. The scopes of reservoir engineering study are PVT analysis, Material Balance Analysis, History Match 'production and pressure regarding Gas Reserve Estimation and Recovery Calculation. After all these some forecast scenarios have also been evaluated.

For updating of the gas reserve, old reports, seismic data, Well logs, Log Evaluation reports, Interpreted logs, new production and pressure data, and other relevant data for Narshingdi gas field were collected from Petrobangla. Use of Shut in Bottom Hole Pressure (SBHP) Survey data for determination of GIIP is industry recognized standard practice. While working with ECLIPSE-100 software it was observed that Shut in Bottom Hole Pressure (SBHP) Data are not available. This has made the job somewhat difficult. As an alternative Shut in Well Head Pressure (SWHP) and Flowing well Head Pressure (FWHP) data were used. Because of data limitations, efforts were taken to use SWHP and FWHP data for reserve analysis of the field. During reserve estimation, some reasonable assumptions were made where data were not available. Assumptions are as follows-
• Rock compressibility.
Water PVT.

• Capillary Pressure = 0.
No aquifer support.

The initial gas in-place has been estimated by using simulation model (ECLIPSE-100). After that this result has been compared with the figures found by two other method called volumetric calculation and material balance analysis. According to simulation model the total gas reserve is about 364.51 Bcf where upper and lower gas sand contain 83.852 Bef and 284.662 Bef respectively. Between these two gas sands(upper and lower gas sands), only the lower gas sand has been developed. So no material balance calculation is performed for upper gas sand. The material balance analysis gives the possible range of GIIP for the lower gas sand 250-315 Bcf. According to volumetric calculation gas reserve for upper gas sand is 78.87 Bef and lower gas sand is 274 Bef. The estimated GIIP by three different methods shows the significant consistency.

Some variables like permeability, fluid contact, well productivity index, pore volume, initial pressure have been changed to obtain a good match to the observed well and reservoir behaviour. Since there is no strong aquifer pressure support in the lower gas sand, so gas production continues from the lower gas sand of the reservoir due to pressure depletion which may limit the future gas recoverable volume.

The result of the forecast indicates that the future recoverable volume from the lower gas sand will increase by 112Bef by the end of field life in 2025. The total gas recoverable volume is 194 Bcf which gives a recovery factor of 68%.
 

Abstract
The Bakhrabad gas field is an old and matured gas field in Bangladesh, which is producing since 1984. This thesis presents a systematic diagnosis of reservoir behavior of this gas field with respect to different flow regimes, reservoir connectivity or compartmentalization, reservoir drive mechanism, estimation of reserve, and nature of production decline. Production data such as flowing wellhead pressure and production rate are used in different simple diagnostic tools like pressure vs. rate, decline and approximated wellhead material balance. The same data is also analyzed with different type curve methods including Fetkovich, Blasingame, Agarwal-Gardner, and Normalized Pressure Integral (NPI) type curves. Commercial production analysis (PA) software is used for this purpose.

Pressure vs. rate diagnosis reveals reservoir flow behavior with approximate duration of flow regimes for the wells of respective sands of Bakhrabad gas field. It is found that Pseudo-Steady State (PSS) flow regime is currently dominating in all producing sands. No compartmentalization is detected in any of the producing sands. Decline diagnosis shows exponential type of production decline in all major sands. Approximate wellhead material balance diagnosis indicates volumetric depletion as the drive mechanism for this field. Type curve analysis show good agreement between production data and the assumed radial reservoir model for this field. The Gas Initially in Place (GIIP) estimated by different methods range from 916 to 1263 BCF, with the most likely value being 1200 BCF. These values compare well with the previously reported values based on volumetric method, which ranges from 1281 to 1392 BCF. Assuming abandonment at 600 psia, the estimated recovery factors range from 53% to 73%.

Abstract
Well test analysis has been used for many years to assess well condition and obtain reservoir parameters from rate and pressure data using different interpretation methods, straight-lines, log-log pressure plots and pressure derivative, complex multilayer interpretation models, numerical model that are able to account for detailed geological features. Well test analysis has become a very powerful tool for reservoir characterization. A case study of buildup pressure behavior of gas wells located in commingled multilayer infinite acting reservoir is analyzed by developing pseudopressure function and its derivatives and a numerical welltest model to estimate reservoir parameters and characterizing the reservoir. Analysis shows that the reservoir is homogeneous at each layer and has medium to poor permeability.

A new milestone has been reached recently with the introduction of deconvolution. Deconvolution is a process which converts pressure data at variable rate into a single drawdown at constant rate, thus making more data available for interpretation than in the original data set, where only periods at constant rate can be analyzed. Consequently, it is possible to see boundaries in deconvolved data, a considerable advantage compared to conventional analysis, where boundaries are often not seen and must be inferred. This has a significant impact on the ability to certify reserves. In this work, entire test data of all wells are dconvoluted using B-Spline deconvolution methodology to identify boundaries and sealing faults is detected in a layer.

The aim of the welltest analysis is to condition stochastic generated realizations by well test data in order to improve simulation of facies and petrophysics in channel sandstone reservoirs. First, it is used the pressure data to estimate the shortest distance from the well to a possible channel boundary and thereby simulate the channel structures. The well test also provides the permeability average in the part of the channel intersected by the well. Together with core-log data and general knowledge of the reservoir, this have been used to simulate permeability. These permeability realizations is input to a numerical flow simulator and compared with the production history. Well test conditioned permeability simulation model improves the rate and pressure history matching.

A recombined reservoir fluid is made and develop fluid PVT properties models to draw phase diagram, simulate CCE, CVD and dew point experiment to estimate gas formation volume factor, gas viscosity. Saturation properties, relative permeability and capillary pressure is modeled from Corey correlation and experimental data respectively. Simulated fluid properties data is input into eclipse simulation model of the studying gas field. Vertical lift curve for gas wells with mist flow is simulated by Gray correlation using down hole gas compressor as artificial lift device and input in full field simulation model. Using all of the simulated data two eclipse dynamic simulation models are developed for two

sections of Titas field. Forty years production rate and pressure history are matched with the simulated rate and pressure data to examine the accuracy of the simulation model. Input different sets of realization of simulated permeability, PVT properties, saturation properties, lift curve to improve the history matching. The best history matching is found using well test conditioned average simulated permeability realization. The full field simulation model which yields the best history matching can be said the representative of the actual field. After selecting the representative simulation model is run to determine some reservoir & production engineering objectives:- estimate reserve & recovery, forecast production & optimize rate, improve recovery & pressure maintenance, field development & reservoir management.

Advanced programming languages and software packages have a wide range of programming code writing facilities and built-in intrinsic procedures & functions which enables to develop a solution of the complex mathematical equations & correlations with minimum error as well as regression facility which allows to adjust the sensitive attributes/coefficients of the mathematical models & correlations to best fit with the observation data to define a system with high level of confidence. Using programming languages and software packages it is possible to generate probability based reservoir grid models, welltest interpretation models & results, welltest interpreted result conditioned pertophysical properties models, and reservoir fluid PVT & saturation function properties models with minimum uncertainty level. The full-field simulation model developed by high confidence level data should give the best history matching and is representing the real reservoir. & recovery estimating, production forecasting & optimizing, enhancing recovery & pressure maintenance, and field development & management decision will be worthwhile when the best representative simulation model is used in reservoir engineering studies which are reflected in this study.

Abstract
Gas Transmission Company Limited (GTCL) was incorporated in 1993 in the unbundling process of gas sector restructuring for owning, operating and maintaining the high pressure gas transmission pipelines forming a part of the national gas grid. Around 70% of total produced gas is transmitted by GTCL pipelines. In order to ensure smooth and efficient pipeline operation, it was decided to incorporate a Supervisory Control And Data Acquisition (SCADA) system by GTCL. It was duly installed and commissioned in 2004.

The main objective of this study is to find out the real impacts of the SCADA system. This is done by carefully studying and itemizing the tangible and intangible benefits directly arising out of the SCADA system. Shortcomings are also identified which need to be removed in order to get maximum benefits from the SCADA system. Financial analysis is performed from two perspectives such as-gas sector perspective and national perspective to justify the implementation of the system. The financial parameters of gas sector perspective reveal that the project is not financially viable while it is viable for national perspective.
 

Abstract
Titas Gas Transmission & Distribution Co. Ltd., a company of Petrobangla which is the largest distribution and marketing company of Bangladesh (72% market share) distributes and markets natural gas in Dhaka City and 21 regional offices outside Dhaka City. 7 (seven) Sales and Revenue zone offices exist in Dhaka City and there are 21 (twenty one) regional Sales offices outside Dhaka City, each having more or less 50,000 Domestic Gas Customers. Currently there are nearly 8,00,000 domestic consumers in the above areas of Dhaka City and the total number of domestic consumers in the Titas Franchise area is 10, 97,478 (up to December, 2006). These consumers are paying bills on monthly flat rate tariff under" Self Billing Process"

TGTDCL introduced some Pre-paid Gas meters in Banani area of Dhaka City as a pilot project. Under this project 1000 Pre-paid Gas meters have been procured, installed and commissioned in the customer premises. One of the objectives of this project work is to undertake financial analysis of using Pre-paid Gas meters. Financial parameters such as net present value (NPV), benefit cost ratio (BCR), internal rate of return (IRR). Pay back period and discounted pay back period and average accounting return (AAR) have been calculated on the basis of 20 year project life. The analysis is firstly done for 10,000 domestic customers. Then it is scaled up to all all the domestic customers in Titas Franchise area. The results of financial analysis infer financial feasibility of the project. Sensibility analysis is also made by varying the parameters such as Gas price, investment cost, gas consumptions through the proposed meters which are the guiding factors of financial indicators (NPV,IRR. BCR. Pay back period, discounted pay back period and AAR). Sensitivity is made considering the worst condition, the best condition and intermediate condition. Less variation in financial parameters for different conditions indicate that the project is less sensitive (less risky). The amount of waste gas for domestic consumers has also been calculated for not using the gas metering system. The amount of waste gas for all the domestic customers in Titas Franchise area are calculated as Tk. 30.73 crore annually.
 

Abstract
Safety is the top most priority in Titas Gas Transmission and Distribution Company Limited (TGTDCL) which ensures uninterrupted supply of natural gas (NG) in greater Dhaka, Mymenshing and Brammanbaria. It is related to the health and environment. Unsafe pipeline is very dangerous for personal, equipment & material, property and environment. To ensure safety, regular inspection of gas pipelines should always be carried out by trained manpower and sometimes along with concerned special authorities to meet the demand of national safety standard and regulations. Physical inspection, continuous sales & purchase monitoring, regular patrolling system are essential for maintaining safety of transmission pipelines. Private security service has been engaged for safety of high pressure pipelines and regular supervision also prevent accidents. The task of replacing the old pipeline by phases has also been taken up to improve safety measures and avoid operational hazards. Program for health and environmental safety improvement has also been taken up. Inspection for safety in pipeline construction phase is given top most priority TGTDCL.

Proper inspection reduces the number of accidents, system loss and increases the financial activities. The company or the premises of the industrial, commercial and domestic customers have been inspected by certified personals help to reduce the system loss. In the financial year, regular inspection and maintenance system loss has comedown to 6.47% compared to 7.06% in the last year-2006. It is possible only by sincere inspection and maintenance the gas pipeline and it's equipments.
 

Abstract
Over the last four and a half decade natural gas has emerged as the only fuel that meets the lion's share of commercial energy requirement in Bangladesh. In this country secured supply of energy is synonymous to supplying of natural gas to a great extent at the present and will remain so for quite sometime in the future. Being produced by three national and four International Oil Companies, gas is distributed by four distribution companies in four regions while one transmission company is entrusted with the responsibility of gas transmission. Government has a plan to extend gas network to the southern region by founding another distribution company. In view of the growing gas demand in different sectors vis-à-vis the resource constraint, it is of paramount importance to have a realistic gas demand projection along with infrastructure development program. However making a projection energy demand projection for a country is at difficult task especially for a long-term given the uncertainties involved.

Historical consumption patterns in different sectors both regional and sub-regional basis has been thoroughly studied for the purpose of this thesis. The non-bulk sectors, industrial and captive power sectors in particular that have manifested remarkable growth in recent years, have been studied with special attention. Historical gas consumption indicates a direct link between industrial sector gas consumption and export earning from manufacturing goods. This study has identified the high growing areas for the industrial consumption and other non-bulk sectors.

Power sector has been the leading consumer of gas and will remain so in the foreseeable future. Forecast for the power sector gas demand has been made as envisaged in the Power sector Master Plan Update 2006 for different GDP growth scenarios. No remarkable change in the fertilizer sector is expected. For long term demand forecast in the industrial and captive power sector, industry categorywise gas demand has been determined considering that the of the weaving sector will continue.

The demand forecast has been presented in three different scenarios viz. Base Case, High Case and Low Case. It is felt that meeting the increasing demand would be a great challenge for the country's gas sector.
 

Abstract
Gas hydrates are two or multi-component crystalline materials formed when free water is available in hydrocarbon gases at reduced temperature. When hydrates are formed in the transmission line of natural gas, they reduce the flow efficiency by reducing the effective diameter of the pipe and also create problems in sensing devices of regulating system.
In winter season, Jalalabad Gas T & D System Ltd. faces a severe gas regulation problem from the formation of gas hydrate at Beani Bazar Gas Regulating Station. When the water vapor and condensate containing gas, coming from Beanibazar gas field, is expanded from 1050 to 550 psig in regulating station, there occurs a lot of temperature reduction and formation of gas hydrate in sensing devices.
In this study, gas hydrate and it phase behaviors are described at various temperature and pressure and some techniques are discussed to overcome the problem of gas hydrate formation. As gas consumption in Beanibazar Gas Regulating Station is very low, the economically viable technique would be de-icing system by alcohol injection. Liquid separation system may apply to improve the effectiveness of the applicable method for prevention of gas hydrate formation problem. Hydrate formation may be reduced, if the set pressure of 1" cut regulating stream in Beanibazar gas station is raised up.
 

Abstract
Exploration, development and production activities for natural gas are technology-driven. These difficult and complex activities will not bring economic prosperity of the country unless the gas is properly utilized. Gas distribution plays a pivotal role in appropriate use of natural gas. It is the vital interface between the industry and the end users. Revenue is brought in by the distribution companies. So for a healthy business, it is imperative that the distribution system runs at the highest efficiency.

Performance of all the distribution companies in Bangladesh is ruined by a phenomenon called "System loss'. It accounts for 8% of the total gas. Apart from very little system requirement of gas (less than 2%) the rest of it is stolen. Technical and administrative flaws in system design, along with improper and old equipment use worsens the problem. Before embarking new network expansion, identification of the existing problems are very important. Titas Gas Transmission and Distribution Company, which is the largest with highest system loss is chosen for the case study.

Identification of the drawbacks in the existing distribution system, suggestions for development of an ideal distribution system and meaningful evaluation of the suggested system are the main objectives of this study. Financial and economic evaluation of the suggested distribution system is mainly conducted to attract private entrepreneurs for investment in the gas sector. Positive reforms both technical and administrative will enhance that possibility even further. Recommendations of these changes are suggested at the end of this study.

Abstract
Natural gas has been an important indigenous hydrocarbon resource in Bangladesh. It is predominant fuel for industries and commercial establishments. The natural gas produced from the reservoir is usually a complex mixture of several hydrocarbons in their liquid and gaseous states, intimately mixed with water. Often, solids and other contaminants are also present in the mixture. Therefore, some processing is required for the produced natural gas before it can be brought to the customer.

The gas processing plants constitute a very important segment of the gas industry in Bangladesh. Currently, there are six companies involved in producing gas from fifteen different gas fields in Bangladesh. These companies operate thirty-nine gas processing plants, using a variety of technologies. Different technologies are involved in removing different elements from natural gas. Therefore, a gas processing plant must combine the appropriate technologies to address the needs of a specific gas field. The selection and design of a processing plant is extremely important for operating a gas field efficiently and economically. This study takes a closer look at all these plants in Bangladesh. A scrutiny of each plant is presented with a view to identify potential rooms for improvement.

Whereas the knowledge and expertise on one particular plant is available, it is extremely difficult to get a broader perspective of the industry because no comparative literature is available. This study attempts to fill in the knowledge base by presenting a comparative study of all the plants currently in operation in Bangladesh. It will be beneficial to all parties interested in the gas processing industry in Bangladesh. It should provide some directives regarding the future of the industry in Bangladesh.

Abstract
Titas Gas Transmission and Distribution Company Limited (TGTDCL) is a gas marketing company, which purchases gas from Bangladesh Gas Field Company Ltd. (BGFCL) and Sylhet Gas Field Company Limited (SGFCL). This gas is transmitted through its own and Gas Transmission Company Ltd's (GTCL) transmission lines to various bulk customers such as Power and Fertilizer Producing Company and distribution network through various City Gate Station (CGS), Town Border Station (TBS), District Regulating Station (DRS) and Metering Regulating Station (RMS) to industrial, commercial and domestic users. In marketing the gas, the company is now facing a major problem, which is known as system loss.
System loss is that portion of gas purchased, which is not accounted for by sales, transfer and company uses or otherwise accounted for. At present the net system loss is approximately 9%. Area wise in some places like Narayangonj, this figure is near about 50%. The present level of system loss needs some reduction to bring it to an acceptable limit.
The main objective of this study is to reduce the unaccountable gas. Identification of various factors related to system loss is carried out. These factors can be classified into two broad classes as a) technical loss, b) non-technical loss. Technical losses are inevitable and the level of the same depends on physical and operating condition of the customer metering stations. Non-technical losses are the man made loss can be many and varies with different factors. The main part of it is pilferage loss through various illegal means like meter tampering, regulator tempering, by pass or un-metered usage etc.
This study covers the definition, classification, calculation, background and present status of system loss. Some of the special causes of system loss with respect to Bangladesh are also discussed. The action program and extended action program to reduce system loss undertaken by TGTDCL and the future plan or recommendation in this regard are also discussed.
 

Abstract
Practicable and realistic reservoir characterization is essential for optimal reservoir management. In this study, a randomized back-propagation neural network model is developed for formation permeability prediction. The model has only one hidden- layer, and the inputs to the model are core porosity, facies identifier, sample thickness, and well sample location. A number of sensitivity studies for permeability prediction are performed. Prediction errors from the model are analyzed and a post- processing scheme for error mitigation is investigated. Neural network responses were compared with those using conventional methods for permeability determination. There are some specific advantages of using the developed model. Characterization of prediction space is observed to be better. However, the limitations of the study were also highlighted. A variety of applications of artificial neural networks in reservoir engineering problems are reviewed in this study.

Abstract
Bakhrabad Gas Field is located approximately 41 miles east of Dhaka in central Bangladesh. The owner of Bakhrabad gas field is Bangladesh Gas Fields Co. Ltd. (BGFCL), a company of Petrobangla. Bakhrabad gas field went into gas production in May, 1984 at the rate of 25 MMscfd. There are 8 (eight) wells in Bakhrabad Gas Field. Once gas production rate from Bakhrabad gas field was slightly above 200 MMscfd from 8 (eight) wells in 1992 to meet the major portion of country's demand. Because of overproduction, the reservoir pressure started to decline rapidly with significant sand and water production. Presently, there are only 4 (four) producing wells with total production of 35 MMscfd. Other wells are shut-off due to pressure decline and water production. The delivery pressure from this field is about 550 psi which is causing under-utilization of Bakhrabad-Chittagong gas pipeline.
At present, it is time to think about some secondary recovery method like installing compressors to recover additional gas from the reservoir. Installing compressor station is one of the techniques to recover additional gas from reservoir as well as maintaining desired discharge pressure of the field. In this study, viability of installing compressor facilities at Bakhrabad Gas Field has been investigated. The required horsepower of the compressor and cooling requirement have been calculated using different approaches. Economic analysis shows that installing compressor facilities is a viable option, that would recover additional gas from the reservoir.
 

Abstract

uncontrolled radiation is dangerous for both public and environment. In petroleum industries, the major sources of ionizing radiation are generation of NORM (Naturally Occurring Radioactive Materials), use of Nuclear Well Logging techniques and Radiography of different machine parts. To control such life threatening hazards, NSRC Act was promulgated in 1993 and NSRC Rules were notified in Bangladesh Gazette in 1997. These Act and Rules are the basis of this research work.

Eight NORM samples were collected randomly from different gas process plants of Bangladesh and the data shows that the radioactivity level for Separator Sludge Sample was 5.47 to 2811.50 pCi/gm [safe limit: 5 pCi/gm] and for Produced Water Sample was 1163.82 to 1424.94 pCi/L [safe limit: 5 pCi/L]. Finally, data are analyzed by geostatistical approach to get model equations and some recommendations are made for ensuring radiation safety.

An extensive Nuclear Well Logging survey was conducted at Titas Well No. 5 and data shows that the safe distance to avoid radiation dose must be 11.5 meter for C's gamma source and 24 meter for 241 Am-Be neutron source. For proper shielding of these two 137 sources, an extra 2.81 cm lead for Cs source and 67.00 cm diameter water shielding for 241 Am-Be source must be used to reduce the radiation dose for well loggers.

For Radiography part, a detail survey was carried out at radioactive source storage pit of Titas Gas Transmission and Company Ltd. and data shows that the diameter of "Controlled Area" for both the two present 192Ir gamma sources are 140 meter. Care must be taken to avoid any sort of source lost situation from the device as the safe distance for these two sources are 500 meter. For proper shielding of these two sources, an extra 4.21 cm lead for 192Ir source [Model No 5476; Serial No. 03840 B] and 4.12 cm lead for 192Ir source [Model No. 5399; Serial No. 03841 B] must be used to ensure radiation safety for radiographers. Besides, the author tried to point out many deficiencies, which should be removed to reduce the radiation dose to the personnel of gas industry of Bangladesh.
 

Abstract
uncontrolled radiation is dangerous for both public and environment. In petroleum industries, the major sources of ionizing radiation are generation of NORM (Naturally Occurring Radioactive Materials), use of Nuclear Well Logging techniques and Radiography of different machine parts. To control such life threatening hazards, NSRC Act was promulgated in 1993 and NSRC Rules were notified in Bangladesh Gazette in 1997. These Act and Rules are the basis of this research work.

Eight NORM samples were collected randomly from different gas process plants of Bangladesh and the data shows that the radioactivity level for Separator Sludge Sample was 5.47 to 2811.50 pCi/gm [safe limit: 5 pCi/gm] and for Produced Water Sample was 1163.82 to 1424.94 pCi/L [safe limit: 5 pCi/L]. Finally, data are analyzed by geostatistical approach to get model equations and some recommendations are made for ensuring radiation safety.

An extensive Nuclear Well Logging survey was conducted at Titas Well No. 5 and data shows that the safe distance to avoid radiation dose must be 11.5 meter for C's gamma source and 24 meter for 241 Am-Be neutron source. For proper shielding of these two 137 sources, an extra 2.81 cm lead for Cs source and 67.00 cm diameter water shielding for 241 Am-Be source must be used to reduce the radiation dose for well loggers.

For Radiography part, a detail survey was carried out at radioactive source storage pit of Titas Gas Transmission and Company Ltd. and data shows that the diameter of "Controlled Area" for both the two present 192Ir gamma sources are 140 meter. Care must be taken to avoid any sort of source lost situation from the device as the safe distance for these two sources are 500 meter. For proper shielding of these two sources, an extra 4.21 cm lead for 192Ir source [Model No 5476; Serial No. 03840 B] and 4.12 cm lead for 192Ir source [Model No. 5399; Serial No. 03841 B] must be used to ensure radiation safety for radiographers. Besides, the author tried to point out many deficiencies, which should be removed to reduce the radiation dose to the personnel of gas industry of Bangladesh.
 

Abstract
This thesis discusses the energy use in Eastern Refinery Limited and the possibilities of energy conservation. It illustrates various processes, equipment and system oriented approach of energy conservation. The objective of energy conservation can be achieved by auditing the energy consumed in every process unit and then to save energy, various steps are to be taken including designing more efficient and compact process units like heat exchanger, furnace etc, revamping existing equipment or overall BMRE (Balancing, Modernization and Rehabilitation)

This study on energy use and conservation possibilities was carried out in Eastern Refinery Ltd. (ERL), the only petroleum refinery plant in Bangladesh. ERL has five processing unit; the study was kept limited to Crude Distillation Unit, the main unit of the refinery plant. Eastern Refinery Ltd. was designed in the mid-60's and went on stream in 1968. At its early stage energy conservation was not so stringent as it is now in a refinery of 2001. ERL has taken necessary steps to improve the plant's efficiency and to conserve energy. ERL is now processing 1.3-1.4 million MT of crude oil per annum, as against its installed capacity of 1.5 million tons per year.

Furnace is the major consumer of energy, usually obtained by burning hydrocarbon fuel. It is estimated that total energy consumption of ERL is about 60.54 MMkcal per hour of which distillation furnace alone is consuming near about 28.62 MMkcal/hr (47.27 %). It has been found that, the furnace is running with a thermal efficiency about 65 % and operating with about 77 % excess air which is much higher than the designed value(40%). 1-2% improvement in thermal efficiency is possible by reducing excess air to the furnace only and through proper monitoring. It has been found that 1% improvement in thermal efficiency in the furnace will result in energy saving of around 3256 MMkcal per year and savings in terms of money around Tk.22,34,104.00 per year.

Energy consumption in ERL per barrel of Crude oil processing is about 0.05 MM kcal. The overall processing expense of Crude oil is increasing every year. In 1990- 91 financial years it was Tk.32.88 per Barrel and in the year 1999-2000 it increased vii to Tk.58.70 per Barrel. About 4 99 MMkcal heat is wasted to cooling water during cooling products from process unit before transferring to storage tank. Heat exchanger can be placed before LGO and Residue water cooler, to save heat energy of about 3.99MM kcal /hr. A reasonable amount of energy can be saved by increasing flashing rate of crude oil in flashing drum before feeding to furnace, to avoid heating the same in the furnace.

Abstract
After the beginning of production, pressure transients propagate outwardly towards the reservoir boundary that changes the pressure around. This introduces the concept of radius of drainage and time to stabilization of a reservoir. The pressure change at the wellbore would be felt at least infinitesimally everywhere in the reservoir. Many authors have defined the radius of drainage and time to stabilization, based on different criterion values that is the percentage of pressure change or flow rate is compared to wellbore condition. The primary objectives of this study are to recognize and evaluate the importance of criterion values for defining the radius of drainage and time to stabilization.
A correlation has been proposed that will allow one to determine the radius of drainage as a function of criterion values. The relationship between a pressure criterion and the corresponding rate criterion has also been established. As expected, an estimated value of the radius of drainage varies considerably depending on the suggested criterion.
The time required to reach the stabilized condition for any reservoir is infinite. In this study an stabilized condition has been defined as that time at which the rate of declining pressure at the well bore becomes negligible. This has lead to generalized forms of time to stabilization correlations.
 

Abstract
Exploration, development and production of natural gas in Bangladesh are of great importance and plays vital role in our economy. In Bangladesh exploration activities commenced from the beginning of the ninteenth century. After several phases of exploration work by government organizations and international oil companies (IOCs) an overall good success ratio in drilling has been achieved. Despite our geologically prospective areas our exploration and development of reserves is limited because of our technical and financial limitations.

After independence, Bangladesh has made several policy changes including legislative and contractual frameworks and competitive incentives offered in favour of foreign participation. The international scenario in oil and gas sector is changing and in this regard Bangladesh is getting positive responses from a number of IOCs to develop this sector. This report reviews Bangladesh's exploration history and reveals gas development strategies. It also discusses the current situation and forwards key suggestions in our present policy and contractual framework.
 

Abstract
Exploration, development and production of natural gas in Bangladesh are of great importance and plays vital role in our economy. In Bangladesh exploration activities commenced from the beginning of the ninteenth century. After several phases of exploration work by government organizations and international oil companies (IOCs) an overall good success ratio in drilling has been achieved. Despite our geologically prospective areas our exploration and development of reserves is limited because of our technical and financial limitations.

After independence, Bangladesh has made several policy changes including legislative and contractual frameworks and competitive incentives offered in favour of foreign participation. The international scenario in oil and gas sector is changing and in this regard Bangladesh is getting positive responses from a number of IOCs to develop this sector. This report reviews Bangladesh's exploration history and reveals gas development strategies. It also discusses the current situation and forwards key suggestions in our present policy and contractual framework.
 

Abstract
Production data for many gas condensate producing wells all over the world have shown that the productivity is severely curtailed when the flowing bottom-hole pressure is less than the saturation (dew point) pressure of the in-place fluid. It is generally accepted that this reduction is due to accumulation of condensed liquid near the wellbore.

A reservoir simulation study by EXODUS (Implicit Compositional Simulator) is conducted to address this issue for the Kailashtila gas field. Fluid composition and phase behavior studies are also conducted using gas chromatograph, PVT apparatus and HYSIM simulator

The results have revealed that the productivity impairment due to condensate accumulation near the wellbore is not likely the case for the Kailashtila Gas Field during its entire depletion life at the current rate of production. Considering the nature of the reservoir and fluid of the other existing fields in Bangladesh, this conclusion can also be a benchmark for them.
 

Abstract
Total number of gas fields in Bangladesh since the discovery of the first one in 1955, now stands at 22. Chatak gas field was the first field in Bangladesh to come on production. It came on commercial production in 1960 to supply gas to the cement factory and the pulp and paper mill. Out of 22 gas fields, 12 fields are now in production. Natural gas contains methane (93.50% to 98%), ethane (0.21% to 3.65%), propane (0.05 % to 1.1%), butane (0.01% to 1.52%), etc. LPG is a mixture of propane and butane or its individuals. Most of the LPG in the natural gas now is not separated but left behind. Only 5000 MT of LPG per annum is being produced from natural gas of Kailashtilla gas field by Kailashtilla LPG Plant, which has come into production in 1998.

Gas production data of different producing fields, gas reserve, gas composition, present gas consumption trend, gas demand and production forecast have been discussed. Existing gas processing systems and LPG development have been evaluated. LPG reserve has been estimated and future gas processing system has been suggested for augmenting its production.

Properties and different type of use of LPG have been discussed. Since government has given priorities to use LPG in domestic sector, only domestic sector has been considered in order to estimate LPG demand. Its use in domestic sector can help reduce the dependence on imported kerosene and deforestation. Market analysis shows that LPG has excellent economic benefits over fuel wood and kerosene. Finally, various effects relating to the extraction of LPG from natural gas have been discussed.
 

Abstract
Artificial Lift Energy Optimization Consortium (ALEOC) was formed by eleven oil companies operating in the Permian Basin with the primary goal of improving oil field operations through sharing experiences. Since the great majority of wells in the Permian Basin some type of artificial lift method, the consortium focused mainly on artificial lift. Beam pumping system received special attention because of its overwhelming amount of usage and economic significance. The combined effort to optimize beam pumping systems called for the creation of a central database, which would hold beam pump related data from diverse sources and would offer ways to analyze the data to obtain valuable insight about the nature, magnitude and trend of beam pump failure.

The database mentioned above has been created as part of this work. The database combines beam pump failure data from about 25,000 wells owned by different companies into a single, uniform and consistent format. Moreover, two front-end computer applications have been developed to interact with the database. These applications offer facilities for easy access to the database, to run queries, and to make plots form the query results, thus saving valuable engineering time that would have been necessary to master a relational database management system (RDBMS) software. One application is designed for desktop, while the other one is designed for the Internet. Both applications calculate failure frequencies of pump, rod, and tubing and summarize the results in various ways. They also store the plots and queries in spreadsheets for further analysis.

Failure frequency is used as the basis of performance comparison among the different companies and areas. Much useful information can be gathered from failure frequency comparison, such as the most vulnerable component in the system, the best and the worst performers, and the most troublesome operating area. Such information can be used for benchmarking performance, identifying best design/operational practices, and for estimating economic impact of failure rate increase or decrease. Thus a cross-company database has proven useful and constructive for identifying areas with room for improvement. Results from data analysis show that the pump has the highest probability of failure in a beam pumping system, followed by rod string and tubing string. The overall failure trend in the Permian Basin is downward, meaning a general improvement of performance of all companies.
 

Abstract
Bakhrabad Gas Field is located in the district of Comilla, about 35 km east of Dhaka city. Production from this field started in May 1984. A total of 8 wells were drilled in the five developed sands of this field. Two workover wells were put into production experiencing shortened producing life. However, only five wells are still producing from three sands.
In the recent years the production of gas from this field declined sharply. Fourteen years of production data have been analyzed using conventional material balance, flowing material balance and reservoir simulation to verify initial gas in place and reserve estimates for the Bakhrabad Gas Field. Four different approaches of the material balance study have led to consistent initial gas in place and reserve estimates for this field. The prediction of future field performances involves the determination of reservoir pressure depletion and offtake rate of gas. Efforts have been made to understand the water production behaviour while analyzing the production data of Bakhrabad Gas Field.
This study estimates initial gas in place, recoverable reserves and remaining reserves of Bakhrabad Gas Field.
 

Abstract
In a reservoir engineering study, pressure transient analysis and reservoir simulation are very important to know different reservoir information and predict future production performance. This study uses pressure transient analysis software SAPHIR and simulation software EXODUS to find out reservoir characteristics and production scenarios of Haripur oil field A reservoir model has been built both for pressure transient analysis and reservoir simulation Two different cases have been simulated to study the possibility of a gas cap. The reservoir model takes into account the high viscosity effect, wellbore storage, skin, heavier hydrocarbon, wax accumulation inside the tubing and different possible inner and outer boundary conditions
The model has been validated by comparing the results of the pressure transient analysis with those of IKM analysis published in the literature Also the simulation results have been verified by comparing total simulated production from the Haripur 1 (Sylhet 7) with the actual production until its production stopped on the 14th of July. 1994
The pressure transient analysis has yielded the wellbore storage coefficient, permeability. reservoir capacity and skin factor which are very close to those obtained from the IKM study. In the simulation study, the well has produced at much lower flowrates than the actual flowrates, but the total production figures are very close. From the simulation study, it has been established that initially the reservoir has no gas cap. The causes of the production stoppage have also been analyzed using the available information in the literature.
 

Abstract
Simulation of the Kailashtilla II gas processing plant (at Golapganj, Sylhet) has been undertaken using the Hyprotech's standard simulator 'HYSIM'. First, the simulation of the gas processing plant has been performed to simulate the plant based on the design parameters and then the performance of the plant has been studied using the operating data of different hours of a particular day. During the simulation of the plant, some changes have been made in the process flow diagram due to limitation of the HYSIM simulator, which cannot handle molecular sieve dehydration system. The simulation has been performed based on the modified flow diagram with the design data. Due to the changes in the process flow diagram some small differences have appeared in material and energy balances.

Abstract
Use of compressed natural gas (CNG) in vehicles can help reduce the dependence on imported liquid fuel with significant environmental benefits compared to conventional fuels. Natural gas resource in the country can help satisfy the growing energy demand of the road transport sector. The most important aspects of vehicular applications of CNG are presented in this study. Criteria considered include: gas quality, safety, technology. environment, economics and marketing issues.
The octane rating, heating value, Wobbe index, and other properties of natural gas make it suitable for use in vehicle applications in place of the conventional fuel. Natural gas is also a very safe fuel in terms of its properties and containment safety. Environmental benefits provide an important argument for using natural gas in vehicle applications. Natural gas produces significantly less amount of harmful emissions compared to the conventional liquid fuels.
Different types of refueling systems, conversion of the existing petrol and diesel engines to natural gas systems and also the storage of natural gas have been discussed. The analysis shows an excellent return on the investment for conversion of passenger car and city transit buses. Finally, various marketing issues relating to the use of natural gas in vehicles have been discussed.
 

Abstract
Most reservoirs are heterogeneous in nature. Reservoir heterogeneity can be in the vertical direction (layered reservoirs) as well as in the radial direction (composite reservoirs). Fluid flow is complicated for the gas reservoirs because of the inertial and turbulence effects and the pressure dependence of gas properties. This study develops a semi-analytical model for pressure transient analysis of heterogeneous gas reservoirs. Reservoir heterogeneity has been considered by drawing upon the layered and composite nature of the reservoirs. The diffusivity equation has been solved as a generalized eigenvalue problem utilizing the pseudopressure and pseudotime schemes. The model takes into account the high velocity effects, wellbore storage and skin, and different possible inner and outer boundary conditions. Finite formation damage can also be modeled.
The model has been validated by comparing the results with those of some analytical models and simulation results published in the literature. Different schemes for calculating high velocity effects have been studied and evaluated. For the same amount of skin, both thin and finite damaged zone responses have been compared. Both these responses have been found to be quite different for certain cases. All possible outer boundary conditions, partial penetration and bottom water conditions may be studied. Its is enormous in the field of pressure transient analysis of gas reservoirs. This versatile model, to my knowledge, includes more features for gas reservoirs than any other previously published pressure transient models.
 

Abstract
Cyclic steam stimulation (CSS) is the commercial oil recovery process of choice for the Cold Lake oil sands. Much of CSS is performed under fracture pressures and, as a result, performance predictions are difficult. This work presents a new mathematical model, involving analytical techniques, for CSS performance prediction. The model is based upon a fracture heating computation, coupled with fluid flow-both during steam injection and oil and water production. Thus two-phase flow is accounted for. Two situations, involving different flow geometries, bracketing actual flow in the field are considered. These consist of fracture flow, and flow in an elliptical geometry with a circular well in the centre.

A vertical fracture is assumed to be created during steam injection. Fracture half length is calculated either from an analytical formula or provided by the user. No mechanistic approach is taken to do any stress analysis. An investigation for a completely closed fracture during production is performed. Based on the results from this investigation, existence of a partially open fracture during production is suggested.

An improved average temperature calculation technique and a new method of evaluating the effect of spatial oil viscosity distribution have been incorporated into the new model.

The model is used to simulate previously reported results showing an excellent match. A sensitivity study for the variation of different parameters produces a reliable response from the model. It is capable of predicting various production performance parameters (i.e. calendar day oil rate, oil-steam ratio, water-oil ratio, oil recovery etc.) of the CSS process. The water-oil ratio prediction is restricted to the first five cycles only. The model can serve as a valuable adjunct to numerical simulation or physical modelling.
 

Abstract
Pressure and production behavior of horizontal wells in steady-state, anisotropic reservoirs were investigated in this study. Five types of boundary conditions were considered: (1) a large gas-cap reservoir with impermeable bottom and lateral boundaries; (2) a large gas-cap reservoir with bottom-water aquifer and impermeable lateral boundaries; (3) an edge-water drive reservoir with horizontal and three of the lateral boundaries as impermeable; (4) a reservoir under nine-spot injection with impermeable horizontal boundaries; and (5) a reservoir under line-drive injection. Analytical solutions were developed for pressure, pressure derivative, shape factor, and productivity index of horizontal wells in these reservoirs. The effects of various reservoir parameters such as wellbore length, formation thickness, and permeability anisotropy on horizontal well productivity were investigated. Shape factors for a wide range of these parameters were obtained. In addition, the effects of wellbore location and mechanical skin factor on the productivity index were studied.

Horizontal well performance in steady state reservoirs is affected by the type of reservoir under consideration. Each reservoir type will yield a different productivity index than the other types. It was found that for a given reservoir, the productivity is directly proportional to the length of the horizontal well. However, if the formation is susceptible to damage due to drilling fluids, the gain in incremental productivity (associated with longer horizontal wells) decreases as the mechanical skin factor increases. Analysis of the results will indicate if the damage had significantly affected the well performance or if a stimulation treatment had been successful in removing the damage.