The usual suspects have planted their flags along the dusty byways of the Permian Basin, declaring where they’ve staked claims. There are names like Royal Dutch Shell Plc, Anadarko Petroleum Corp., Pioneer Natural Resources Co. And, on signs fronting a barbed-wire fence, BHP Billiton Ltd. For the world’s largest mining company, the heart of the U.S. shale boom in West Texas might seem to be strange territory, a very long way from the iron-ore deposits of Australia or the copper mines of Chile’s Atacama desert. But BHP actually has been in the oil business for years, with operations stretching from...