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AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA

Exploration in Synclinal Areas of Tripura Fold Belt, India: A Re-found Opportunity

A. K. Jena1; N. C. Das2; G. C. Saha3; Asim Samanta4

(1) CEWELL, ONGC, Vadodara, India.

(2) Block-III,WON, ONGC, Vadodara, India.

(3) CEWELL, ONGC, Vadodara, India.

(4) CEWELL, ONGC, Vadodara, India.

Recent exploratory successes in synclinal parts of Sundalbari and Khubal structures of Tripura Fold belt in stratigraphic plays of Bhuban formation of Miocene age attracts attention of the Geoscientists to think a bit unconventional hitherto being considered as risky. In structures of Tripura Fold Belt, the entrapment of gas is mainly structural and limited to anticlinal highs. Till now, the exploration was mainly limited to these highs only. But a bit deviation from the conventional anticlinal exploration, the adjacent broad flat synclines were targetted for stratigraphic traps with a bit of caution. Thin low resitivity sands belonging to a relict feature of Upper Bhuban formation in the adjacent eastern synclinal area of Sundalbari structure produced gas @1,60,000m3/d. Similarly a sand belonging to Middle Bhuban formation of Miocene age produced gas @1,45,000m3/d. in Khubal structure, which is also in synclinal area. These successes have come at a right time when the synclinal exploration had taken a back seat after a number of failures in synclinal areas. The thin sands embedded in thick shale sections of Bhuban formation with small culminations have trapped hydrocarbon. The updip pinchouts in the limbs of the anticlines in adjacent synclinal areas, fault closures in plunge parts of the structures, unconformity related entrapments are the potential targets. The understanding of stratigraphic traps, their trapping mechanism has brought these successes. These discoveries have established that a significant regional potential exists in the synclinal areas of Tripura Fold Belt.