As creditors line up for the assets of recently deceased oil titan Aubrey McClendon , an energy-investment firm already has claimed some of his most valuable holdings. EIG Global Energy Partners owns small stakes once held by Mr. McClendon in some 8,500 wells across the U.S. drilled by Chesapeake Energy CHK 6.42 % Corp., the oil and gas producer that Mr. McClendon co-founded and ran until 2013. EIG lent Mr. McClendon more than $1.2 billion over several years to pay for his personal stake in the wells. It gained control of those stakes by foreclosing on the loans last year, after collecting cash and data from the properties since 2009. That trove of data about U.S. drilling helped EIG weather the oil downturn by prompting its executives to sell out of some oil-production investments […]