My last non-announcement post promised a prelude to a real post. This is the poorly attempted fulfillment of that post. So yes, despite having left for Turkmenistan nearly a week ago, this is not a post about Turkmenistan. Those will come. Maybe.
I came across this article about "fracking" (the word I loathe) and ground water pollution. I am not an industry shill and I want to believe that I value truth and rigorous science more than almost anything else. The central claim of the ground water contamination is that it is higher in wells close to wells than areas not near wells. It does not really bother me that the study used lacks baseline measurements for water pollution. It's not really realistic to have data before a perceived problem occurs because then why would anyone be out collection that data. While the article doesn't go into details about the study methodology, I would like to believe that they measured pollution levels everywhere reasonably possible (or in randomly selected wells) and then mapped that against distance from nearest well(s). It would also be useful to know about distance from water well to gas well at ground level and also about distance from water well to nearest part of well trajectory underground as many wells are now drilled with significant horizontal components. Regardless of the study methodology, I would not be surprised if this study was accurate and that future studies also returned similar results. By accurate, I mean the correlation between proximity to the well and water contamination and not what the article title states.
What I actually find bothersome is the title of the article, which the article does a very poor job of trying to support. The title says "Fracking for natural gas is polluting ground water, study concludes" but the second paragraph of the article states "evidence for methane contamination of drinking water associated with shale-gas extraction". I find this bothersome because shale gas extraction does not equal hydraulic fracturing. In fact, a later quote is "the Duke researchers said that the presence of methane likely was due to its escape from faulty drill casings." Again, that does not seem to implicate the fracturing process. To be perfectly frank, it is also not simply the casing that is at fault. In fact, it is most likely not the casing that is the direct problem. So many things to try and explain.
I want to revisit a comment I made about the study methodology about the distance from a water well to the gas well at surface and under the ground. With many wells having a large horizontal section in them, directionality is important. Imagine a scenario where there is a gas well that goes down for 3 km and then turns to be horizontal for about 1 km. Or, imagine an upside-down bendy straw and Daniel Day Lewis screaming “I drink your milkshake!” (I am not intimately familiar with the well profiles in Pennsylvania but that’s not really the point). Now, imagine two water wells. They are both 1 km away from the gas well at surface, but one is directly above the horizontal section and the other is on the opposite side. The hypothesis I want to present is this: The two water wells, all other things being equal should have similar levels of contaminants. Even though they are very different distances from the actual production zone of the well, they are the same distance from the surface of the well, and more specifically the same distance from where the well intersects the water table which I contend is the most likely source of contaminants. My contention is that the actual fracturing process, which, through the use of pressure, sand, water, and chemicals, places a great deal of “stuff” into the reservoir section of the well which is along the horizontal portion of the well does not somehow alter the geology in a way that leads to “direct” contamination through percolation up through many layers of rock. This sort of study is very feasible. Many good conclusions could likely be reached with adequate data. And the data is all “gettable” with the right support and resources and if we believe energy supply/security, water safety, and public health are worthwhile issues, then the resources should exist.
I am willing to make a few more contentions about where pollution can come from. If you agree that proximity to the well’s surface location has the strongest correlation with water well pollution, then one should be able to also agree about the available options for contaminant sources. Contaminants then either come from the well location via spills at surface on the wellsite or they come from the well, but travel along the well trajectory back to the water table (which tends to be very shallow compared to the gas well depth). Surface spills are easy enough to understand. Chemicals are spilled at the surface and leach into the soil and into the water table or into a stream and end up in the water supply. Contaminants from the well might be a bit harder to grasp and can generally be said to come from one of two processes. The first is the actual drilling and construction of the well. Things like drilling fluids (aka: mud) are used when drilling the well and they inevitably must get through the water table. Also, cement slurries pass the same zones when casing sections are cemented in place. A question about contamination to pose is what specific contaminants are seen in the water wells and do they match up with products known are likely to be used during the well construction phases? The second process is during hydraulic fracturing and subsequent production from the well. Fracturing exerts significant stress on the well and this can damage the cement that surrounds the casing which can lead to communication (of the non-oral variety) between different sections of the well. Note that I did not say it should damage the casing itself. With the right grade of casing, the stress of hydraulic fracturing should not damage the casing. However, that stress gets transferred from the casing to the cement surrounding the casing and can create cracks in that cement. Force exerted on the casing causes the casing to expand slightly which means the cement also needs to expand slightly (sort of). This puts the cement in tension in one direction and cement is typically very weak in tension. The fracturing process also involves a number of proprietary and not-fit-for-human-consumption chemicals. Could these chemicals migrate through the cracks in the cement up to the water table and into water wells? It is a possibility that is worth investigating so we need to ask the same question that we did during the well construction process: what specific contaminants are seen in the water wells and do they match up with products known are likely to be used during hydraulic fracturing?
Now, we circle back to the original cause of my angst: that damn article title. It’s simply not right. The oil and gas industry would benefit greatly if it engaged in more pro-active education about what they are doing and why it can be considered important. You could call it lobbying, but that is a loaded word and not quite apt. If the industry wants to lead this issue and do what is in its best long-term interests, then it needs to demonstrate that there are either no problems with current industry practices or that the problems that do exist have solutions. By the way, there are always problems so the question is what solutions do we have? Tighter chemical handling practices at the wellsite? Sure, why wouldn’t we want to do this. Better and more environmentally drilling and cementing chemicals for water table zones? Definitely possible. Better cement for enduring stresses of hydraulic fracturing? It already exists. The industry can either lead this issue or have the terms dictated to them. The prompt for this post, an in accurate article title, is but one example that the industry is not showing leadership on this issue.