After the discovery of hydrocarbons in two wells in an initial frontier drilling campaign, Cairn Lanka (Private) Limited has decided to undertake the second exploration phase for a deepwater block in the Mannar Basin offshore Sri Lanka.

The SL 2007-01-001 block lies off the island’s west coast, with the operator planning to get underway with drilling a fourth well in the licence from 1 February. “The drillship, Discoverer Seven Seas, is already on location,” said Suni Bharati, director of Cairn India Ltd, which owns Cairn Lanka.

The subsidiary has advanced the spud date of the fourth well by three months after the rig became available earlier than originally expected. The initial plan was to start drilling by mid-2013.

In the second phase Cairn will acquire an additional 600sq km of 3D seismic data and drill the fourth well to assess the potential commerciality of the reserves.

Bharati said that the company would take a decision on the possible development of oil and gas fields there after the well results are known later this year.

The operator has already reprocessed 1,000sq km of 3D and 5,700 line km of 2D data; it has also acquired, processed and interpreted 1,750sq km of 3D data (as against the licence commitment of 1,450sq km); a bathymetric survey, satellite and other studies.

It has previously drilled three exploration wells in SL 2007-01-001 during the first exploration phase, with two of the probes hitting gas and condensate – LPL-Dorado-91H/1z and CLPL-Barracuda-1G/1. The third well, CLPL-Dorado North 1-82K/1, was plugged and abandoned as a dry hole in December 2011.

The operator discovered a 25m (82 ft) hydrocarbon sandstone column in the first well (Dorado), which was drilled in a water depth of 1,354 m (4,442 ft). It was predominantly gas-bearing with some additional liquid hydrocarbon potential, said Cairn after the discovery. It was the first well to be drilled offshore Sri Lanka in 30 years and the first to discover hydrocarbons.

The second well (CLPL-Barracuda-1G/1) was drilled in a water depth of 1,509m (4,951 ft) and hit 24 m (79 ft) of hydrocarbon-bearing sandstone reservoir.

The block, awarded in 2008, covers more than 3,000sq km with water depths ranging from 400-1,900m (1,312-6,234 ft) in the Mannar Basin. It is located adjacent to India’s Cauvery basin, where several discoveries have been made.

Cairn Lanka hold a 100% interest in the SL 2007-01-001 block.