By OGJ editors
HOUSTON, Jan. 23 -- Cairn Energy PLC, Edinburgh, reported that a significant oil discovery has followed a long string of tantalizing smaller successes in the Rajasthan basin in northwestern India.
Cairn Energy estimated oil in place at 450 million to 1.1 billion bbl and said 50-200 million bbl might be recoverable at the as yet untested N-B-1 exploration well on 5,000 sq km Block RJ-ON-90/1.
The company holds 100% interest in the block, and state Oil & Natural Gas Corp. Ltd. has a right to 30% of any development area resulting from a commercial discovery on the block.
The operator said the discovery is on a large simple structure 60 km north of Saraswati.
UK analysts Wood Mackenzie said that eventual recoverable volumes could total 110-260 million bbl, pending appraisal, from N-B-1 and three earlier discoveries on the block: Guda in 1999, Saraswati in 2001, and Raageshwari in 2003.
More drilling, tests
Cairn Energy was reviewing its program to allow early appraisal drilling of the N-B-1 discovery and exploratory drilling of similar nearby prospects.
It drilled N-B-1 to 1,250 m and had not yet reached TD when it found the oil. It ran an intermediate log and evaluated fluid samples of 24° gravity oil from the Fatehgarh formation.
The well encountered two reservoir sections. One is a 136 m log evaluated gross oil column in silty sands of the Barmer Hill formation. Net pay is estimated at 22 m with 21% average porosity.
The other is a 185 m log evaluated gross column in "excellent high quality Fatehgarh sands," the company said. Net pay is estimated at 85 m with 25% average porosity and an oil-water contact.
Bill Gammell, Cairn Energy chief executive, said, "While further evaluation and appraisal is required I am confident that this discovery in isolation has the potential to transform the value of Cairn's portfolio."
The main exploration play objectives encountered in the Rajasthan basin, commencing with the stratigraphically youngest formation, are the Thumbli, Dharvi Dungar, Barmer Hill, and Fatehgarh.