BP Plc is set to partner with Chevron Corp. to bid for a South China Sea exploration block. Chevron will have a 60% stake in the block and act as operator with BP holding the remaining interest. CNOOC Ltd a unit of China National Offshore Oil Corp, (CNOOC) has the right to take a 51% stake in the block if the companies make a commercial oil or natural gas discovery. However, it was not known whether CNOOC would exercise pre-emption rights on the asset.