[FORM 6-K CNOOC Limited 65 Floor Bank of China Tower One Garden Road Central, Hong Kong CNOOC Finance (2015) Australia Pty Ltd Australian Company Number 604 822 335 65 Floor Bank of China Tower One Garden Road Central, Hong Kong CNOOC Finance (2015) U.S.A. LLC 65 Floor Bank of China Tower One Garden Road Central, Hong Kong x ¨ Form]