Shallow prospect evaluation in Shahbazpur structure using seismic attributes analysis, Southern Bangladesh.

Abstract:

Shahbazpur structure is located within the Hatia trough a southern extension of prolific Surma Basin, where lies all of the largest Gas fields of Bangladesh. A method is established to delineate the structural mapping precisely by interpreting four 2D seismic lines that are acquired over Shahbazpur structure. Moreover direct hydrocarbon indicators (DHI) related attributes analyzed for further confirmation of presence of hydrocarbon. To do this synthetic generation, seismic well tie, velocity modelling and depth conversion has been performed. Seismic attribute analysis used in this study is mostly related to bright spot identification in reservoir zones as well as to identify the similar response in both below and above of the reservoir zones. Seismic interpretation shows that Shahbazpur structure is roughly an oval shaped anticline with simple four way dip closure which will be a good trap for hydrocarbon accumulation. A limited number of seismic attributes functions that are available in an academic version of Petrel software are applied to analyze attributes. Taking in consideration of possible interpretation pitfalls, attributes analysis confirmed that bright spots exist in the shallower part of the structure above the present reservoir zones which might be a potential shallow gas reserve. The bright spots are located within Shahbazpur sequence I of Dupi Tila Group of Pleistocene age and Shahbazpur sequence II of Tipam Group of Pleistocene-Pliocene age. This signature will play a very important role in next well planning on the same structure to test the shallow accumulation of hydrocarbon. For better understanding of this shallow reserve, it is suggested to acquire 3D seismic data over Shahbazpur structure which will help to evaluate the hydrocarbon accumulation and to identify gas migration pathways.