What is Associated Petroleum Gas (APG)? Associated gas, also known as Associated Petroleum Gas (APG), is essentially natural gas that emerges from the ground together with crude oil. If you’ve ever seen flames burning above an oil field at night, that’s associated gas—also referred to as APG. Imagine oil companies drilling for oil and not just getting black liquid, but also gas coming up along with it. This gas is associated gas. Sometimes it’s dissolved in the oil, and sometimes it floats above it. It is natural gas extracted from the ground alongside crude oil. https://www.kaitiangas.com/what-is-associated-petroleum-gas-apg/