3rd World Congress on Petroleum Refineries and Natural Gas Recovery 2018
"...Petroleum Congress 2018 is a thick, black to yellow, flammable liquid mixture of hydrocarbons. Petroleum occurs naturally, mainly below the Earth's surface, and is believed to originate from the accumulated remains of ancient plants and animals. It is the source of petrochemicals and is used to make gasoline, lubricating oils, plastics, and many other products..."