BHP Billiton expects to undertake more acquisitions in the booming US shale gas sector after its $US15.1 billion ($A14.13 billion) takeover of Petrohawk Energy, chief executive Marius Kloppers says.

BHP Billiton expects to undertake more acquisitions in the booming US shale gas sector after its $US15.1 billion ($A14.13 billion) takeover of Petrohawk Energy, chief executive Marius Kloppers says.