Abstract: Petroleum Potential of the Banni Graben, Kutch Basin

SEDGELEY, DAVID, SHAREEN YAWANARAJAH, and RAVI BASTIA

The Banni Graben of the Kutch Basin is located within the continental passive margin of Western India. Its architecture and structural fabric were primarily controlled by the prevailing Precambrian orogenic trends. Plate reconstructions suggest that this graben was along-trend with the Diego, Majunga, and Morondava Basins of northern Madagascar before the break-up of Africa from India. This position is significant for petroleum exploration because of the known source potential of rift sediments in Madagascar, where the 24 billion barrel heavy oil Bemolonga tar sand was apparently sourced by lower Triassic shales. The interpretation of an analogous stratigraphic section in the Banni Graben enhances its exploration potential. A single seismic traverse across the basin shows an asymmetric half graben structure with its axis near the Kutch Mainland Fault. Seismic and gravity data suggest about 5000 m of sediment fill the graben, including at least 1500 m of untested Triassic or older rocks. The older stratigraphic section often exhibits onlap events to the basement and has not been penetrated by existing wells. Two-dimensional gravity models constructed using structure derived from depth-converted seismic and density information from rift sediments in Madagascar and East Africa match the observed gravity field and support the seismic interpretation. Due to the paucity of paleontological data, the stratigraphic interpretation of wells near the Banni Graben is poorly constrained. The basal sediments are generally described as Middle Jurassic but available paleontological data and similarity to lower Jurassic-upper Triassic rift sediments in Madagascar suggest a possible older age.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria