Feb 9 (Reuters) - BHP Billiton (LON:BLT) Ltd BHP.AX :
* Mad Dog Phase 2 project investment approval
* Approved expenditure of US$2.2 billion for its share of development of Mad Dog Phase 2 project in Gulf of Mexico
* Production is expected to begin in 2022 financial year for Mad Dog Phase 2 Project Source text for Eikon: Further company coverage: BHP.AX,BHP.L