Apache Corp. Executive Vice President Kregg Olson, who oversees corporate reservoir engineering and has worked for the company for 26 years, is retiring effective Aug. 1. Senior Vice President Dave Pursell, now in charge of planning and market fundamentals, is to assume responsibility for reservoir engineering when Olson retires. Before joining Apache in early 2018, Pursell was managing director of investment banking for Tudor, Pickering, Holt & Co. He previously was head of macro research and a founder of Pickering Energy Partners Inc. and also has been director of upstream research at Simmons & Co. International. Pursell has a bachelor of science and a master of science in petroleum engineering from Texas A&M University.