ANALYSIS OF GAS TRANSMISSION NETWORK OF BANGLADESH A Thesis Submitted to the Department of Chemical Engineering In partial fulfillment of the requirements for the Degree of Master of Science in Engineering (Chemical) By PRADIP CHANDRA MANDAL 1111111111111111111111111111111111 #96119# DEPARTMENT OF CHEMICAL ENGINEERING BANGLADESH UNIVERSITY OF ENGINEERING AND TECHNOLOGY, DHAKA BANGLADESH FEBRUARY 2002 RECOMMENDATION OF THE BOARD OF EXAMINERS The undersigned certify that they have read and recommended to the Department of Chemical Engineering, for acceptance, a thesis entitled Analysis of Gas Transmission Network of Bangladesh submitted by Pradip Chandra MandaI in partial fulfillment of the requirements for the degree of Master of Science in Chemical Engineering. Chairman (Supervisor) 4~~: .... Dr. Edmond Gomes Professor Dept. of Petroleum and Mineral Resources Engg. Member (Co-Supervisor): ~.Q,:-:,.~).(:,~ . Dr. A K. M. A Quader Professor Department of Chemical Engg. Member: ~:~~.~ . Dr. Ijaz Hossain Professor and Head Department of Chemical Engineering BUET, Dhaka. Member (External): ......................................deG'~_ . Dr. AH.M. Shamsuddin Chief Geologist UNOCAL Bangladesh Ltd Lake View House No. :12, Road No. :137 Gulshan, Dhaka 1212. Date: February 19,2002 ABSTRACT The gas transmission pipelines in Bangladesh were initially planned and constructed targeting particular bulk consumers or potential load centers. In the early stage of the development of the gas sector, the grid system was possibly not visualized. But over the years the gas transmission system has expanded considerably and has become complicated. The objective of the study is to perform gas transmission network analysis of Bangladesh. The study has been undertaken to simulate the present network system, identify its limitations and suggest remedial measures. This study would be useful to understand the performance of the present gas transmission system of Bangladesh. This study would also analyze the existing pipeline capacity and examine the level of capacity utilization. The work was completed with the help of a commercial software, PIPES 1M-Net. After pressure matching at different load centers, manifold stations and branches, different scenarios were studied for future performance prediction. Finally, the scenarios were discussed and highlighted different important points through conclusion and recommendation. The simulated results will be helpful to identify the bottlenecks and to plan for future expansion of gas transmission system. There are twenty-two gas fields in Bangladesh. But twelve producing gas fields can produce 1300 MMSCFD of gas from 53 gas wells. The study shows that Ashugonj metering station is the focal points of the National Gas Grid. Gas from the North-Eastern Gas Fields are being transported through the North-South pipeline to Ashuganj Manifold Station of GTCL from where it is further transmitted to Titas franchise area (TFA) and Bakhrabad franchise area (BFA) through Brahmaputra Basin pipe line and Ashuganj- Bakhrabad Transmission pipe lines. From Bakhrabad Gas Field, Bakhrabad-Chittagong Pipeline transports part of the required gas for Chittagong. The remaining gases for Chittagong is supplied from Salda, Meghna and Sangu gas fields. The results show that effective pipeline diameter of major transmission lines have decreased due to condensate accumulation. Hence pigging is necessary. Rashidpur- Ashugonj loop line is essential to supply growing gas demand. It will increase the . capacity of the North-South pipeline by 456 MMSCFD. To meet the future gas demand of the Western region, the results show that another loop line is necessary from Rashidpur-Ashugonj loop line to Dhanua. It will increase the supply of Ashugonj-Elenga pipeline by 175 MMSCFD. Analysis also shows that it is a better option to install a compressor station at Bakhrabad to transmit the low-pressure gas of the field through the high-pressure pipeline. ii ACKNOWLEDGEMENT I would like to express my deep respect to Dr. Edmond Gomes, Professor of the Department of PMRE, for his valuable guidance and supervision throughout the entire work. I would like to express my profound gratefulness to Dr. A.K.M.A. Quader, Professor of the Department of Chemical Engineering, for his valuable supervision of the work. I would like to thank Engr. Kh. A. Saleque, GM (R-A Project), GTCL, for his co- operation in providing me with the permission in collecting gas transmission data and valuable suggestions. I would like to express my gratitude to Mr. Tahshin Haq, Engineer, UNOCAL Bangladesh Ltd., for providing data and encouragement to complete this work. I would like to thank A. K. M. Shamshul Alam, GM (Planning and development), JGTDSL, for his administrative support and co-operation, and for providing me with necessary facilities in collecting the required gas transmission and distribution data. I would like to express my profound gratefulness to my parents for their support and to my brothers and sisters, for their support and inspiration. I would also like to thank the University of Alberta-BUET -CIDA linkage Project officials for setting up computer facilities in PMRE department, which made this work possible. iii USEFUL CORRESPONDENCES Abbreviations, Acronyms and Terminology A-B Ashugonj-Bakhrabad N-S North-South B-D Bakhrabad-Demra B-C Bakhrabad-Chittagong A-E Ashugonj-Elenga MAOP Maximum Allowable Operating Pressure SCADA Supervisory Control and Data Acquisition TFA Titas Franchise Area JFA Jalalabad Franchise Area BFA Bakhrabad Franchise Area WFA Western Franchise Area R-A Rashidpur-Ashugonj Petrobangla Bangladesh Oil Gas and Mineral Corporation (BOGMC) UFFL Urea Fertilizer Factory Limited ZFCL Zia Fertilizer Company Limited APS Ashugonj Power Station CUFL Chittagong Urea Fertilizer Limited BCIC Bangladesh Chemical Industries Corporation EPZ Export Processing Zone IOC International Oil Company NGFF Natural Gas Fertilizer Factory PSC Product Sharing Contract PUFF Pol ash Urea Fertilizer Factory SHELL Shell Bangladesh Exploration and Development B.Y. UNOCAL UNOCAL Bangladesh Ltd. iv Operating Companies of Petrobangla BAPEX Bangladesh Petroleum Exploration Company Limited BGFCL Bangladesh Gas Fields Company Limited BGSL Bakhrabad Gas System Limited GTCL Gas Transmission Company Limited JGTDSL Jalalabad Gas Transmission and Distribution Systems Limited RPGCL Rupantarita Prakritik Gas Company Limited SGFL Sylhet Gas Fields Limited TGTDCL Titas Gas Transmission and Distribution Company Limited Terminology for metering stations CGS City Gate station, the pressure is being reduced from the transmission pipeline pressure down to 350/300 psig. TBS Town Bordering Station reduces pressure from 350/300 psig down to 150 psig. DRS District Regulating Station reduces pressure from 150 psig down to 50 psig. Symbols, Measures and Conversion Factors 3 K = 10 Lac = 105 (Bangladesh Terminology) 6 M = 10 (except for MCF) Crore = 107 (Bangladesh Terminology) 9 G = 10 I ton = 1000 kg I barrel (bbl) = 0.159 cubic meter I BTU = 0.252 kilocalorie MCF = thousand standard cubic feet TCF = Trillion (1,000 billion) cubic feet I psig = 0.06895 bar I atmospheric = 14.7 psia v ( TABLE OF CONTENTS . 'Page Chapter No. Abstract HI Acknowledge III Useful Correspondences IV-V Table of Contents VI-IX List of Tables X List of Figures XI-Xll1 List of Appendices XIV 1-3 J. Introduction 4-34 2. Literature Review 2.1 Introduction 4 2.2 Types of Pipelines 5 2.2.1 Gas Pipelines 5 2.2.1.1 Gas Gathering 5 2.2.1.2 Gas Transportation 6 2.2.1.3 Distribution Pipeline 6 2.2.2 Oil Pipelines 6 2.2.3 Product Pipeline 7 2.2.4 Two-phase pipeline 7 2.2.5 LNG Pipelines 7 2.3 Uses of Natural Gas 7 2.4 Sector Wise Natural Gas Consumption 8 2.4.1 Ammonia-Urea Fertilizer Sector 10 2.4.2 Trends of Natural Gas Uses for Power Generation 13 2.4.3 Industrial, Domestic and Commercial Sectors 17 2.5 Gas Sector of Bangladesh 19 2.5.1 Oil and Gas Exploration in Bangladesh 19 2.5.2 Gas Fields of Bangladesh 22 VI 2.5.3 Present Demand and Supply Scenario 27 2.5.4 Future Demand and Supply Scenario 30 2.6 Gas Transmission Network 32 3. PIPESIM 35-41 3.1 Introduction 35 3.2 PIPESIM-Net 35 3.3 Black Oil and Compositional Data 36 3.4 Calibration Data 37 3.5 Model Overview 38 3.6 Network Validation 39 3.7 Flow Correlations 39 3.7.1 Horizontal Flow 39 3.7.2 Vertical Flow 40 3.7.3 Single Phase Correlations 40 3.8 Convergence 41 42-51 4. Gas Transmission System and Related Data 4.1 Introduction 42 4.2 Network Analysis 42 4.3 Gas Composition 46 4.4 Diameter and Length of Transmission Lines 49 5. Steady- State Flow of Gas through Pipes 52-71 5.1 Introduction 52 5.2 Gas Flow Fundamentals 52 5.3 Types of Single-Phase Flow Regimes and Reynolds Number 53 5.4 Pipe Roughness 54 5.5 Pressure Drop Calculations 55 5.5.1 The Pressure Drop due to Potentia! Energy Change 55 5.5.2 The Pressure Drop due to Kinetic Energy Change 55 5.5.3 The Frictional Pressure Drop 56 vii 5.6 Allowable Working Pressures for Pipes 57 r 5.7 Allowable Flow Velocity in Pipes 57 5.8 Horizontal Flow 57 5.8.1 Non- Iteration Equations for Horizontal Gas Flow 58 5.8.2 A More Precise Equation for Horizontal Gas Flow (The 59 Clinedinst Equation) 5.9 Gas Flow through Restrictions 60 5.10 Sub-Critical Flow 60 5.11 Critical Flow 61 5.12 Flowing Temperature in Horizontal Pipelines 61 5.13 Steady-State Flow in Pipeline Networks 62 5.13.1 The Mathematical Models for the Individual NCE's 63 5.13.2 Loop Less System 65 5.13.3 Looped Systems 66 5.13.3.1 Single-Loop System 67 5.13.3.2 Multiple-Loop System