it only loosely takes into account the total BTU of energy produced not all the byproducts and equipment that needs energy to be replaced. 5 million homes heat with heating oil 70 million homes heat with NG. 26 million tons of bitumen for asphalt roads You can assume 13 million tons of shingles going to the dump each year are replaced with shingles using again bitumen. ~10% of fossil fuels consumed per year go to making plastics

Again when you refine or produce OIL you don't just get one or the other. Most of the power generation in Mexico (over 50%) is literally just the waste NG from producing oil from the shale in western USA. (We were previously just burning this off at the wells btw)