Oklahoma City-based Warwick Energy Group has closed its purchase of oil-and-gas company R/C Sugarkane LLC, owner of 7,300 net acres in the Eagle Ford Shale, company officials say. Warwick, whose investment funds has interests in more than 5,000 U.S. oil and gas wells, acquired R/C Sugarkane from affiliates of Riverstone Holdings LLC, a New York-based private equity firm. Officials didn't disclose the price of the purchase, which was announced in April. Privately held R/C Sugarkane's acreage…