Block M covers an area of 3,011 sq. km. It comprises of onshore acreage relinquished to the Government at the end of 2003, as well as an area lying at the southern part of the Belait District. Block M has been explored since the beginning of the last century with the first successful well, Belait-2, drilled in 1913. The Belait-2 well produced a total of 33,000 barrels of oil between 1924 and 1931. Ten wells were drilled before the Second World War. Eight more wells were drilled later - Belait 11 to 14 in the mid 1950’s and Belait 15 to 18 in the 1970’s and 1980’s. Many of these wells were drilled in the Talingan area and encountered good oil and gas reservoirs. Nevertheless, a huge portion of Block M remains unexplored.

PetroleumBRUNEI and the Block M consortium signed the Production Sharing Agreement on 28 August 2006. The current consortium members are: Tap Energy (Borneo) Pty Ltd (Tap) (39%) – as the operator, Kulczyk Oil Brunei Limited (36%), China Sino Oil Co. Ltd (21%) and Jana Corporation Sdn Bhd (4%).