I wish I could find more about what clean-up they have to do with the gas. I found on their web site talking about separating out the natural gas liquids, but little else.
Typically, it takes a Natural Gas Processing plant to bring wellhead gas to pipeline quality for use by consumers, regardless if that consumer is residential or industrial.
The article mentions that the vehicles are run on either diesel or natural gas. Are you saying that the vehicles are specially designed to take gas right out of the ground or that the article doesn’t mention that the portable CNG trucks have to take their CNG to a secondary refiner before it can be used by the drilling company vehicles.