It is ALL of the gas produced from the field regardless of where it ends up. Most of it is gas that comes out of solution as the liquids rise upward in the production tubing and that amount must be produced if you want the liquids. Problems occur when liquids around the well bore are produced fast enough to allow free gases to reach the well bore and become entrained. That phenomena is referred to as "Coning" in the business.
Coning is a natural phenomena in oil and gas fields but does not apply to tite reservoirs like we are dealing with here. Coning is caused by the pressure drawdown in the vicinity of a well where significant vertical permeability is present. This decidedly is not the case here and I seriously doubt any familiar with the phenomena would disagree.
There are several possibilities which might be the answer on why higher gors are occuring.
One, a review of individual wells could be made to determine whether a single well is progressing toward higher gors. If not, then what was said before that higher gor wells being targeted would be the case made.
Now about higher gor wells. The gors are all pretty low, as <2,000 scf/b is a darn low gor. I am not worried at all about damaging the reservoir performance at such a low gor. if it were 10X as high, perhaps.
The natural, in situ oil resides in the Bakken at somewhere between 200 scf/b up to 1,800 scf/b.
Every barrel produced will contain that amount of gas when reservoir conditions remain above the bubble point.
There is a complexity in these tite reservoirs as one travels away from the wellbore such that nearer to the wellbore one is below the BP and gradually gets above the BP away from the wellbore. In other words, the oil/gas in the formation exists not as a single phase but at different pressures, hence different phase regimes.
The bottom line is this: increasing GORs is reflective that a larger portion of the reservoir is being produced below the BP. This is as expected.
It is not a bad thing right now as gas being released from oil drives the oil to the pressure sink of the well, so one can produce more.
When it gets bad for the reservoir, as
@Bigun correctly states, is when gas is accumulated enough it no longer pushes the oil but reaches a saturation high enough to flow to the well independently of the oil. This means the energy of the reservoir is depleting without the benefit of producing oil.
No one has ever witnessed an oil reservoir this tite through its life cycle to know what happens when this occurs, so we are all up in the air to see if a sudden drop in oil happens and when. I do suspect a gradual event will occur rather than catastrophic.
Sorry about the dissertation, my engineering side is showing up.
