ABSTRACT: Marine early Permian in Bengal Basin: implications for hydrocarbon exploration

Trivedi, K. B. and A. K. Biswas , Oil & Natural Gas Corporation Ltd, Dehradun, India

The Bengal Basin covering an area of 90,700 sq. km. situated in eastern part of the Indian peninsula is one of the major sedimentary basin of the world. Lot of exploratory efforts has gone into the basin for hydrocarbon exploration and plethora of knowledge generated envisaged three petroleum systems(!) in this basin.

The oldest petroleum system belongs to pretrappean/ Gondwana sequence with Rajmahal volcanic eruptions of Albian-Aptian age as dividing line. This sequence is resting over North easterly oriented Middle Proterozoic mobile belt (MPMB) and owes the formation of depocenters to the rifting of Indian plate from Antarctica. The Antarctica highland, Gamburtser was the provenance dispersing sediment through radial fluvioglacial drainage system.

Based on the study of 2150LK of 2D seismic investiga-tions and well data, tectonics, movement of plates and occurrence of Marine flora from wells of east coast basins, their assemblage similarity from established rich Marine Permian assemblage from pre-LATHI sediments of Jaisalmer basin, authors have conclusively established, Marine incursion during early Permian which is evident as transgressive onlaps on Proterozoic basement and basal Talchir Fm. A definite Paleoshore line is being established. Seismic investigations indicate upto 1600m thickness for this sequence. These marine Permian sediments are also correlatable with west coast of Madagascar where marine Permian flora are being reported from Vohitolia fm.

These sediments have added a totally new arena of hydrocarbon potential for Gondwana sequence in Bengal Basin because of the organic richness of marine beds and their maturity due to deeper burial as evident by drilled well data.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia