Accumulation of Oil in Coal-Bearing Strata North of Ahmedabad

The main oil sands of the Cambay Basin in the area north of Ahmedabad are in the Kalol Formation of upper Eocene age. The lower coal slit member of this formation can be identified all over the basin. In the fields north of Ahmedabad, this unit comprises mainly of coal and is identified as the reservoir unit. Hydrocarbon accumulations are found within high pressure lenses of poorly permeable silts within the coals. Study of the nature and environment of deposition of the reservoir rocks and a study of the development of the Kalol structure vis-a-vis the depositional and structural history of this part of the basin with the help of palaeostructural profiles and the production performance of the reservoir rocks provide some indication of the nature of distribution and accumulation of hydrocarbons in the area.