The Oil Wells That Will Never Recover
It is very common today to read about shutting-in of producing oil and gas wells to reflect the reality there are fewer and fewer places to store oil right now. An old oilfield maxim-the cheapest storage is in the ground. It wasn’t coined to meet the criteria that are extant today as regards surface storage limitations, but rather to reflect costs of production versus sales prices. As we are all learning though, these two scenarios are very much related.
I get a lot of questions from readers of my articles, and students in my Reservoir Drill-In Fluids design classes about what happens with oil and gas wells that are shut-in. As discussed, there is a lot of this going on right now due to the oil glut we are experiencing. That answer is generally, that there are definite problems associated with doing this, but it’s not guaranteed they will occur in every instance. Sometimes you just get lucky. More often than not though, the sub-surface gremlins that reside in oil and gas reservoirs are going to get you. There is a reason that service companies earn billions of dollars annually pumping stuff down wells to fix perceived problems with production. So the question before us now is what are some of the mechanisms that cause problems restoring production to oil and gas wells after they have been shut-in?
One thing that can happen to oil and gas wells when they are shut in after being on production is a change in wettability. We will discuss ‘wettability’ in some detail in this article, but essentially amount to the surface wetting condition of the discrete particles of sand and other constituents that comprise the rock in oil and gas reservoirs. Water coning is one frequent contributor to this problem.
Note- the discussion that follows is not comprised of absolutes. I am in no way saying that the phenomena I'm putting forth here happen automatically, every time. They can and do happen on a large scale, but each individual well is subject to its own unique circumstances. That's why we need engineers! Read more