Once a leaky well, always a leaky well? That is the question. Here’s what we know: about 5% of unconventional gas wells leak right off the bat; upwards of 50-60% leak within 20ish years. In a Canadian study, the failure rate approaches 100%. This is why even the most optimistic dog will agree there’s little safe about living next to a well pad.
This in from one of my readers:
This isn’t quite a precise answer to your question but does provide some context. “A Canadian research team investigated the mechanisms for [casing] failures, and determined that concrete shrinkage which leads to well casing fissures is essentially inevitable in a fifty-year time frame…The probability that a project scope of as few as ten gas wells will impact ground water within a century approaches 100%; ground water will be contaminated”http://www.damascuscitizens.org/Bishop-Report_R1.pdf
I’ll just leave it at that for the day. If anyone has any good news, I’m all ears! I can’t help but think there are some pro-industry folks who read my blog. Now is the time for you to write in and give me a little hope that scientific studies like this one are irrationally based.
Unfortunately, I’m afraid they’re quite sound. They all lead to the same practical application: Err on the side of caution.
ada.mae.compton 
Click to access Soter_thesis.pdf
Unfortunately this shows too many things can and o go wrong with the cement casings.
In a nutshell…Kevin Sorter (who now works for Haliburton as a work over expert) speaks about the delimma of SCP Sustained Casing Pressure. When the valve is closed, the well should not build up in pressure. The pressure guideline is that the pipe burst rating should not exceed 20%. No one solution exists for SCP. Cement shrinkage makes the vertical fractures grow in height into gas bearing formations. Gas diffusion becomes continous with decreased pressures at or near the surface due to gas leak off. http://www.sciencedirect.com/science/article/pii/0920410593900168 confirms this statement. The abstract states.. “The migration of gas from oil and gas formations to the surface is a problem that greatly affects those surface areas where human activity exists. Underground gas storage facilities and oil fields have demonstrated a long history of gas migration problems. Experience has shown that the migration of gas to the surface creates a serious potential risk of explosion, fires, noxious odors and potential emissions of carcinogenic chemicals. These risks must be seriously examined for all oil and gas operations located in urban areas.”
You have put your finger on the cardinal error of engineering– monument belief. The irrational idea that by making something of a material that is strong at the time of “design,” it will remain that way. It never does. Concrete has a limited structural life. All things do, as per:
http://holyjoe.org/poetry/shelley.htm
Ozymandias was at least only trying to monumentalize his vanity. If you are counting on a monument to contain a deadly pollutant that you encased…. well, there is no nice way to say it. You are killing future people.
Proof that I have astute and learned readers who carefully critique the answers! Thanks, all.
Interesting. My father built many highway bridges in NEPA in the ’60s. Concrete is critical and if not poured exactly right under exactly the right conditions, it is not good. As children, we never saw him because he was always out on the job nearly 24/7 monitoring the poured concrete piers to which were added the new thing, pre-cast concrete. He could see it, touch it, and watch it cure. And fix it if necessary. Not so with these deep underground casings. Oh yes, it may hold up but not forever even if it is done properly. If you drive the NE Tpke Ext or I-80, you will see two large bridges being completely replaced, piers, spans and all. I guess even PADOT knows that their useable lifetime is limited, maybe 50 years?