The Barmer Basin, Rajasthan, India—the Ingredients Which Led to Exploration Success

Pierre Eliet, Richard Heaton, and Mike Watts
Cairn Energy PLC, Edinburgh, United Kingdom

Cairn Energy's focus on Rajasthan, north eastern India has resulted in a number of significant recent oil and gas discoveries. In January 2004 the company made the billion barrel STOIIP Mangala discovery. Four additional discoveries made after the discovery of the Mangala field highlight the potential of the Barmer Basin, Rajasthan as an emerging oil province.

The Barmer Basin is a tertiary rift system situated in NW Rajasthan between the Cambay Basin and Jaisalmer Basins. It is a northern continuation of the Tertiary Cambay rift system.

The basin is underlain by a Proterozoic basement of intrusions, extrusives and meta-sediments. The basin initiated with extensional rifting, followed by a strike-slip episode and fault reactivation which produced localised inversion. The syn-rift phase of the basin is of Paleocene to early Eocene age and the post-rift phase is Eocene to recent. The Paleocene is largely fluvial to lacustrine or occasionally marginal marine with biostratigraphic signatures indicative of arid climatic conditions.

While the primary play elements of source, trap presence and a working migration pathway were proven by the early wells drilled by Cairn and Shell in the basin, good reservoir was perceived as the primary exploration risk prior to the Mangala discovery. The Mangala field and the additional discoveries have confirmed the presence of stacked fluvial sand systems. This significant reservoir fairway of thick, high poro-perm Paleocene reservoir sands can be mapped over large areas of the northern basin. The Mangala-1 discovery well was the 15th well drilled by Cairn in the basin.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005