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Future Strategy for Exploration in Tripura, Assam Arakan Fold Belt, India

Nirmal C. Das, Gyanesh Chandra, and M. C. Kandpal
Assam & Assam Arakan Basin, Oil & Natural Gas Corporation Limited, Jorhat, India

The crescent shaped depression filled with sediments along the north eastern promontory of the Indian plate, forms the Assam Arakan Basin. A southwest-northeast oriented deep seated fracture encompasssing Hail Hakalulla lineament and eastern part of Dauki fault and the Naga thrust in the north-east differentiates the Basin into two mega tectonic provinces with striking different structural styles. Southern province is generally known as Assam-Arakan fold belt. Fold belt is characterized by a series of enechelon narrow elongate anticlines aligned in submeridional to meridional trends with westerly convexity complicated by incipient wrenching and thrusting. Apart from these, transverse faults are also observed cutting across structures. Some of them have regional extension.

Tripura Fold belt area of Tripura state of India constitutes the western most province of Fold belt. So far exploration efforts in the Fold belt area is guided by the narrow anticline crests with mixed success. Exploratory inputs expended in Tripura fold belt has resulted in identification of 17 exposed structures and few concealed structures out of which 15 prospects have been probed by drilling. Of these, 9 prospects have been established as gas bearing in Neogene sediments of Miocene age. Recent discoveries of hydrocarbon in northern plunges of Agartala Dome, Tichna and Gojalia anticline gives impetus to new exploration strategy in the future.

A study has been carried out to study the mechanisms for hydrocarbon accumulation in these new finds. Hydrocarbon entrapments occur in anticline noses as stratigraphic traps and stati-srtutural traps aided by NE-SW trending transverse faults. The results of the study will help in formulating future exploratory strategy in this area.

Presentation GEO India Expo XXI, Noida, New Delhi, India 2008©AAPG Search and Discovery