British oil explorer Dana Petroleum has drilled the Cormoran-1 exploration well located in Block 7 offshore Mauritania to a total depth of 4,695m below sea level.

The well, which lies about 2km to the south of the Pelican-1 gas discovery well that was drilled in late 2003, has been plugged and abandoned as a gas discovery.

Stabilized gas flow rates of between 22 and 24 million standard cubic feet per day (mmscfpd) were obtained during a test of one of the four separate gas columns encountered by the well.

The primary purpose of the Cormoran-1 well was to test the Cormoran prospect, which adjoins but lies at a greater depth than the Pelican discovery.

A secondary exploration objective was the Petronia prospect, which lies beneath the Cormoran prospect.

The Cormoran-1 well encountered generally thin but good quality gas-bearing sands within the Pelican Group at depths between 3,376m and 3,711m true vertical depth subsea (TVDSS).

This interval comprised two gas columns, one in the Upper Pelican Group (3,376m to 3,420m TVDSS) and one in the Lower Pelican Group (3,691m to 3,711m TVDSS).

Good quality gas-bearing sands were also encountered within the Cormoran prospect, in the gross interval from 4,351m to 4,471m TVDSS, and at the top of the Petronia prospect, in the gross interval from 4,660m to 4,695m TVDSS.

Drilling was stopped at a depth of 4,695m TVDSS for operational reasons (elevated pore pressures), and the well was still in gas-bearing reservoir section at this depth, the company said.

A drill stem test was carried out across a 33m interval in the Lower Pelican Group (3,679m to 3,712m TVDSS), and stabilized flow rates of up to 22 to 24mmscfpd were obtained on a 32/64" choke, the flow rate being constrained by the need to avoid sand production.

Following the test, the Cormoran-1 well was plugged and abandoned in such a way that the well could be re-entered in the future, Dana said.