U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh By USGS-Bangladesh Gas Assessment Team Petroleum Systems and Related Geologic Studies in Region 8, South Asia Edited by Craig J. Wandrey U.S. Geological Survey Bulletin 2208-A The Bangladesh gas resource assessment was conducted under the purview of the Participating Agency Service Agreement (PASA) signed between USAID and the U.S. Department of Energy (DOE)—PASA No. 388-P-00-99-00026. The 2-year agreement expires on August 19, 2001. The PASA provides for assistance to the Natural Gas Sector pursuant to which the resource assessment was jointly carried out. PASA also envisages transfer of new technology, modeling practices, and geoscience theory from existing and established programs in the United States to the Government of Bangladesh, Petrobangla, and Bangladesh academia. In preparation for the cooperative assessment effort, Bangladesh geoscientists received training and familiarization from the U.S. Geological Survey in world resource assessment methodology. U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior Gale A. Norton, Secretary U.S. Geological Survey Charles G. Groat, Director Posted online June 2001, version 1.0 This publication is only available online at: http://geology.cr.usgs.gov/pub/bulletins/b2208-a/ Any use of trade, product, or fi rm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government Manuscript approved for publication June 18, 2001 Published in the Central Region, Denver, Colorado Editing, layout, and photocomposition—Richard W. Scott, Jr. Graphics by the authors III Contents Part I—Overview .......................................................................................................................................... 1 Introduction .......................................................................................................................................... 1 Acknowledgments............................................................................................................................... 2 Assessment of Gas Resources of Bangladesh............................................................................... 2 General Geology ......................................................................................................................... 2 The Tertiary Composite Total Petroleum System................................................................... 2 Assessment Units ....................................................................................................................... 3 Part II—Assessment Unit Descriptions.................................................................................................... 6 Bang0101: Surma Basin Assessment Unit....................................................................................... 6 Bang0102: Eastern Extremely Folded Assessment Unit ................................................................ 6 Bang0103: High-Amplitude Faulted Anticlines Assessment Unit ................................................ 7 Bang0104: Moderately Folded Anticlines Assessment Unit......................................................... 7 Bang0105: Western Slope Assessment Unit................................................................................... 8 Bang0106: Western Platform Assessment Unit.............................................................................. 8 Perspective of the Assessment.................................................................................................................. 9 References Cited .......................................................................................................................................... 9 Addendum 1................................................................................................................................................. 10 Assessment Results Summary ........................................................................................................ 10 Assessment Unit Bang0101, Surma Basin, Monte Carlo Results .............................................. 12 Assessment Unit Bang0102, Eastern Extremely Folded Belt, Monte Carlo Results ............... 20 Assessment Unit Bang0103, High-Amplitude Faulted Anticlines, Monte Carlo Results........ 32 Assessment Unit Bang0104, Moderatley Folded Anticlines, Monte Carlo Results ................ 40 Assessment Unit Bang0105, Western Slope, Monte Carlo Results........................................... 48 Assessment Unit Bang0106, Western Platform, Monte Carlo Results...................................... 60 Addendum 2................................................................................................................................................. 72 Assessment Unit Bang0101, Surma Basin, Seventh Approximation Data Form ..................... 72 Assessment Unit Bang0102, Eastern Extremely Folded Belt, Seventh Approximation Data Form ................................................................................................... 75 Assessment Unit Bang0103, High-Amplitude Faulted Anticlines, Seventh Approximation Data Form ................................................................................................... 78 Assessment Unit Bang0104, Moderately Folded Anticlines, Seventh Approximation Data Form ................................................................................................... 81 Assessment Unit Bang0105, Western Slope, Seventh Approximation Data Form.................. 84 Assessment Unit Bang0106, Western Platform, Seventh Approximation Data Form............. 87 Assessment Unit Bang0101, Surma Basin, Known Data............................................................. 90 Assessment Unit Bang0104, Moderately Folded Anticlines, Known Data............................. 105 IV Figures 1. Generalized geologic map of Bangladesh and adjacent areas............................................ 3 2. Estimates of undiscovered natural gas resources of Bangladesh ...................................... 4 Table 1. Stratigraphic nomenclature of Ganges-Brahmaputra delta in eastern India and Bangladesh ................................................................................................... 5 Contributors to This Report USGS–Bangladesh Gas Assessment Team PetroBangla USGS M. Ismail Thomas S. Ahlbrandt Quazi Shahidur Rahman Ronald R. Charpentier Muhammad Imaduddin Timothy R. Klett Humayun Ashraf Christopher J. Schenk Khondaker Shahjahan James W. Schmoker Mizanur Rahman Gregory F. Ulmishek Yousuf Ali Talukder Assessor Robert C. Milici Other Contributors Central Region Energy Team Regional Coordinator Gene Whitney, Chief Scientist Craig J. Wandrey Assessment Meeting Recorder/Graphics Geologist Susan M. Walden Peter D. Warwick GIS Specialist Graphics Specialist Feliks Persits Margarita Zyrianova U.S. Geological Survey–PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh By USGS-Bangladesh Gas Assessment Team Part I—Overview area (or country) in which that total petroleum system is active is then divided into assessment units (AU). Assessment units are areas of specifi c geological terrain and hydrocarbon devel- Introduction opment within a given total petroleum system. Available his- torical oil and gas production data from existing wells and fi elds and information on discovered prospects and leads are A natural gas assessment of the country of Bangladesh then allocated to each AU. The AU is characterized as to was conducted after a 21-month study performed by the U.S. type of hydrocarbon—in this case gas rather than oil—the Geological Survey (USGS) and funded by the U.S. Agency minimum fi eld size to be assessed (42 billion cubic feet of for International Development. This project culminated in an gas (BCFG) for Bangladesh), the number of discovered fi elds assessment meeting that was held in Denver, Colo., from Janu- exceeding the minimum size, and the median size of discov- ary 16 to January 26, 2001. The assessment team consisted ered gas fi elds. Geologic elements may be risked only when of six geologists from the USGS’s World Energy Resource no fi elds of the minimum fi eld size have been discovered Assessment Team and seven geologists, geophysicists, geo- within an AU. In such a hypothetical AU, assessment unit geo- chemists, and a petroleum engineer from Petrobangla. A logic risk probabilities are determined for adequate petroleum regional assessment geologist from the USGS assigned to Ban- charge, reservoirs, traps, and seals—the timing of geologic gladesh presented the geological and geophysical data needed events must be such that traps form in time to intercept migrat- for the formal assessment. International oil companies were ing gases. These probabilities are multiplied together to deter- invited to present geological background and assessment infor- mine the geological risk for an accumulation of one deposit mation and included Unocal Corporation, Shell Bangladesh, equal to or greater than the minimum fi eld size. If there is no and Cairn Energy PLC. The goal was to assess the technically risk that one fi eld of minimum size will be discovered, the risk recoverable undiscovered gas resources of Bangladesh that is 1. Accessibility is also risked to account for the possibility might be found in a 30-year period (2000–2030). of adequate locations to allow for exploration for a fi eld