Originally Posted by tig1
It all comes out of the ground. NG is very dirty when it comes out of the ground and has to be filtered.
What you are talking about is wet gas or dry gas. The closer you get to pure methane the dryer the gas is considered.
In production you. An tell wet gas is in a burner or flare because it smokes while dry gas does not.
Some gas flashed out of hydrocarbon liquids in production, this is usually considered wet, has higher btu's. Some high vapor pressure crudes emit gas in midstream facilities and terminals which is captured in separate sales lines.
All natural gas is treated through a dehydration process (usually glycol trays with converging streams and other chemical treatments to remove unwanted components).
The more valuable "dirty" components are caught at various points as condensate or natural gas liquids and recombined with crude to improve its btu and value on the market.
Basically when a base oil is said to be "Natural gas" based they are speaking of pure methane as the base material. Closer to the purity of what goes to your home stove/minus the mercaptin/ than what comes out of the ground.
I would presume that start gas is as pure and clean as the the stream that PAO is created from.