Hydrocarbon distribution and major controlling factors of Bengal Basin, Bangladesh

The Bengal Basin is a typical remnant ocean basin in the southeastern India subcontinent. Based on the studies of basin evolution, petroleum geology conditions and hydrocarbon distribution characteristics, the gas accumulation regularity and its main controlling factors were analyzed in order to provide references for remnant basins. The Bengal Basin underwent syn-rifting, post-rifting and foredeep episodes, and developed good source-reservoir-cap rock assemblages during the remnant ocean basin development stage. The Oligocene Jenam and Miocene Bhuban shales are the most important source rocks. The Miocene Bhuban and Boka Bil sandstones are the principle reservoir objectives, which were deposited in a tide-dominated delta to shelf environment. The seal is the widely developed Miocene-Pliocene oceanic shales. Traps are mostly anticlines. The Bengal Basin is dominated by gas, and most gas fields distribute in the Surma depression, the Tangail uplift, the Hatia depression and the eastern fold belt on the plane. Gas accumulates in the Miocene Bhuban and Boka Bil formations. Gas distribution is closely related to the formation of remnant ocean basin. The gas-bearing sequence is impacted by basin evolution and gas plane distribution is impacted by the basin framework. Gas exploration should focus on the Surma depression, the Hatia depression and the eastern fold belt in the eastern part of the basin in the near future, and the main objectives are sandstone reservoirs of the Surma Group in the pressure transition zone.