Saudi Aramco to buy liquid natural gas from Sempra Energy, a US company based in San Diego. : Saudi Arabia's state owned oil company will begin buying liquid natural gas from a U.S. company under a 20 year agreement. Saudi Arabian Oil Co., also known as Aramco, said Wednesday it would buy 5 million tons of liquid natural gas per year from Sempra Energy, based in San Diego. Aramco also will make a 25% equity investment in an LNG export facility under development in Port Arthur, Texas, as part of the deal.