(EnergyAsia, April 27) — Hong Kong-listed CNOOC Limited has recently completed its purchase of stakes in upstream projects in Australia and Nigeria. Subsidiary CNOOC Australia E&P Pty Ltd has signed farm-in agreements with Australia’s BHP Billiton Limited and Kerr-McGee Australia Exploration and Production Pty Ltd, a subsidiary of Kerr-McGee of the US, for exploration permits…