Exploration drilling update - Chim Sao North West

PREMIER OIL plc

("Premier" or "the Company")

Exploration drilling update - Chim Sao North West appraisal

17 August 2012

Vietnam

The Chim Sao North West appraisal well, CS-3X, in Vietnam Block 12W has reached a total depth of 4,235 metres. The well has been plugged and abandoned after encountering oil shows in the Middle Dua sands.

 The appraisal well was drilled to determine whether the Chim Sao North West discovery extended into a separate fault segment to the north. The well targeted the Upper and Middle Dua sands. While 135 metres of sandstone reservoir were penetrated in the Upper Dua interval there was no indication of hydrocarbons. In the Middle Dua interval 165 metres of sands were drilled, but only oil shows were encountered.

 The CS-N17XP well, which was completed immediately prior to the appraisal well, was drilled to produce from the North West extension to the Chim Sao Field. That well was brought on-stream earlier this month with initial extended production test rates averaging 4,000 barrels of oil per day from four Upper Dua reservoirs. 

Simon Lockett, Chief Executive Officer, commented

"The information gained from the appraisal well will now be integrated with Premier's existing knowledge to better understand the potential in the other untested areas adjacent to the Chim Sao discovery. Meanwhile, the initial production rates from the Chim Sao North West accumulation are extremely encouraging."

Enquiries

Premier Oil plc 0207 730 1111

Simon Lockett

Andrew Lodge

Pelham Bell Pottinger 0207 861 3232

Gavin Davis

Henry Lerwill