It's not necessarily the oil standard, but Exxon Mobil is one of the world's largest integrated oil companies (with Royal Dutch Shell and BP) engaging in oil and gas exploration, production, supply, transportation, and marketing. In 2015 it had proved reserves of 24.7 billion barrels of oil equivalent, including oil sands assets through Imperial Oil. Exxon Mobil's 23 refineries in 14 countries have a throughput capacity of 5 million barrels per day and daily lubricant basestock manufacturing capacity of 136,000 barrels. It supplies refined products to more than 19,000 gas stations worldwide and is a major petrochemical producer. In 2016 Exxon Mobil CEO Rex Tillerson was nominated to be US Secretary of State.