ABSTRACT: Cambay-Kalol (!) petroleum system in North Cambay basin, India

Samanta, M. K. , Oil & Natural Gas Corporation Ltd, Mehsana, Gujarat, India

The Cambay-Kalol (!) Petroleum system in North Cambay basin, India covering 10750 sq.km contains 680 MMt original in-place oil and Oil equivalent gas in Paleocene-Miocene reservoirs in 58 different oil and gas accumulations. Sediments in this petroleum province range in age from Paleocene to Recent and was deposited in a Tertiary rift basin. Data on carbon isotopic and biological markers indicate that all oils in this system have originated from Paleocene-Lower Eocene Cambay Shale source rock. Evidences suggest oil generation and migration occurred during Early Miocene (25 Ma) to Recent with peak hydrocarbon generation by the end of Jagadia Formation (6 Ma). The overburden is 900 m to 1600 m thick and range from Upper Eocene to Recent. The major reservoirs are Middle Eocene sandstones of Kalol Formation. Other important reservoir rocks are sandstone/siltstone within Cambay Shale / Kadi Formation of Paleocene-Lower Eocene age. Structural accumulations are either associated with block uplifts or block edge folds and combination traps along block boundaries and over structural noses along the plunge of the blocks.

The essential elements of the petroleum system were deposited during Paleocene to Recent. The petroleum system processes occurred from Miocene (25 Ma) to Recent.

The quantity of hydrocarbons generated in Cambay Shale was calculated and compared with estimated in-place oil and gas to determine the GAE of the petroleum system which is about 5 %.

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