Marathon Oil Corp. COO David E. Roberts Jr. resigned effective Friday (Dec. 14) to “pursue other interests,” according to the company. Since joining the Houston-based producer in 2006, Roberts had been considered an important contributor to the upstream business. He was named senior vice president for business development and was promoted in 2008 to executive vice president of upstream, overseeing upstream and production. Roberts became COO when the company spun off its refining operations last year to become a pure-play explorer and was said to be on the short list to succeed CEO Clarence Calazot, 62. The company declined to offer further details.

J. Larry Nichols is retiring as an employee of Devon Energy Corp. effective Dec. 31. He plans to continue to serve as executive chairman and as a director. Nichols’ retirement follows a succession plan announced in June 2010, when Devon President John Richels was promoted to CEO, a post that Nichols had held since 1980. Nichols and his father, John Nichols, co-founded Devon in 1971; the company went public in 1988. Among the company milestones under J. Larry Nichols’ leadership, Devon in 2002 acquired Mitchell Energy & Development Corp., giving it the top position in what was then the emerging Barnett Shale, as well as access to the drilling technology pioneered by George Mitchell, which successfully combined horizontal drilling techniques with hydraulic fracturing well stimulation.

UK-based BG Group plc, which has a bevy of natural gas-related projects across North America, has appointed Chris Finlayson as CEO to succeed Frank Chapman. Finlayson, who is to take over on Jan. 1, currently is executive director of BG Advance. Chapman is to remain as an adviser until he retires in June.

Sen. Ron Wyden (D-OR), the incoming chairman of the Senate Energy and Natural Resources Committee, has named longtime aide Joshua Sheinkman as the committee’s next staff director. Sheinkman will lead the committee’s work to move the U.S. toward a low-carbon economy, improve management of public lands and bolster the nation’s energy security, Wyden said. Sheinkman has served as legislative director to Wyden since 2006. He joined the staff of then-Rep. Wyden in 1993 as counsel and adviser on environment, energy and transportation policy.

James Lambright will join Sempra Energy as senior vice president for corporate development, effective Jan. 2. Lambright, a former CEO of the Export-Import Bank will direct investments, strategic partnerships and acquisitions. Most recently Lambright was COO at Sapphire Energy, a biofuels development company.

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