The state-run company is also thought to be investing $5 billion in developing submerged gas fields in the East China Sea, with the possibility of tapping gas deposits in Japanese waters through diagonal and horizontal drilling methods. The company has already come under scrutiny this month from Green Dragon Gas, which claims that CNOOC breached production sharing contracts by drilling wells on its licences without notification.
In June, China angered Vietnam by inviting IOCs to jointly participate in the development of nine blocks in the waters around Hainan, blocks which Hanoi considers overlap into their maritime territory. CNOOC's usual operating procedure is to team up with foreign firms during the exploration phase, but holds the right to take a 51% in the block once a commercial find is made. PetroVietnam was involved in a dispute with its northern neighbour last December when Beijing accused it of 'unilateral oil and gas exploration activities'.