ABSTRACT: Krishna-Raghavapuram (!) petroleum system in Gudivada Graben, Krishna-Godavari Basin, India

Das, A. K., R. Husain, U. Samanta, R. P Gupta, and P. K. Mishra , Oil & Natural Gas Corporation Ltd, Dehradun, U.P, India

Krishna-Godavari Basin is a passive margin basin on East Coast of India. The basin evolved as a result of Mesozoic rift and drift of Indian plate from Antarctica during the break up of Gondwana land. Gudivada Graben, situated in the western part of the basin, preserves the maximum thickness of syn-rift sediments. The graben is bounded by Baptla Horst to the west and Kaza-Kaikalur Horst to the east. Commercial accumulations of liquid as well as gaseous hydrocarbons have been discovered within both syn-rift and post-rift sediments in Kaikalur-Lingala field over the Kaza-Kaikalur Horst.

A total of five depositional sequences have been identified and mapped in Kaikalur-Ellore area. Sequences 1, 2, 3 and 4 correspond to the syn-rift sedimentary fill, while sequence 5 represents post-rift sediments deposited during first basin-wide marine transgression.

Geochemical data suggest that sequences 2 (Krishna-Formation) and 3 (Gajalapadu Shale) deposited under lacustrine environment in central part of the graben, are the possible source rock units. Sequence 5 (Raghavapuram Shale) is rated to have poor to marginal source rock potential. Channel sands in upper part of sequence 4 (Kanukollu Sandstone) unconformably overlain by Raghavapuram Shale and discrete sands within Raghavapuram Shale are the major reservoirs. Raghavapuram Shale also acts as regional seal. Migration of hydrocarbons is through faults flanking the Kaza-Kaikalur Horst.

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