Replies

The gas is dissolved in the oil. It is compressible, but under the same pressure as the oil. What does change, however, as the gas travels up the wellbore is the volume of the gas. Consider the basic gas law that PV=P'V', (pressure times volume equals the same expression with values altered in proportion), and as the pressure is reduced, the gas expands. So what you are seeing is the gas expanded from formation pressures of roughly 4500 psi at depth to surface pressure of about 14 psi (atmospheric pressure) or about three hundred times the volume it would have as a bubble in the oil in the rock at depth.

The amount of gas present in the oil varies from well to well.

While the pressures are no higher than the casing head pressure, the gas expands as it nears the surface, and until it can be linked to processing facilities by pipeline is burned off as a byproduct of oil production.

In the meantime, the oil is trucked out to shipment facilities and market, helping pay for the well while waiting on the pipeline hookup.

What you see in those night time pictures is the backlog in feeder pipeline construction: about 29% of the gas produced (as a byproduct of oil production) on any given day is flared, although that number is dropping as infrastructure construction catches up.