Lawson, who joined BP in 1990, left the company in November and was replaced by Sam Skerry, who had been leading BP's new ventures division that invests in start-up technology companies, a BP spokesperson said.
Mercuria confirmed Lawson joined as an executive vice president.
Lawson oversaw the sale and acquisition of over $100 billion worth of oil and gas assets, including huge divestments the company had to make to pay for the costs of the 2010 Deepwater Horizon rig explosion in the Gulf of Mexico.
In recent years, Lawson had a key role in shaping Chief Executive Officer Bernard Looney's strategy to shift BP's focus away from oil and gas to renewable energy, including through further sales of oilfields and acquisitions of stakes in offshore wind projects, solar developments and biofuels.
Skerry has been with BP for 25 years and has spent most of her career in the company's supply and trading business.
(Additional reporting by Julia Payne; Editing by Emelia Sithole-Matarise)
By Ron Bousso
