Hydraulic fracturing 5

I hadn’t actually heard about the proposed regulation to subject hydraulic fracturing to the Safe Drinking Water Act. I suppose I’ve been too inundated with the entire horrific healthcare mess to hear much of anything else. I don’t have any problems with Congresswoman DeGette’s proposal – and I’m not just saying that because I voted for her.

Hydraulic fracturing is something that’s actually been in use for quite some time in the United States – at this point, a little bit over fifty years. Obviously, length of use doesn’t necessarily say anything about a practice’s safety; there are plenty of industrial practices that have been in use for far longer that do not-nice things to the environment and to people. I mostly point this out because by now, the practice is ubiquitous in the industry. When I started working for my company* as a temp four years ago, some of the first reports I ever read detailed how formations were being fractured.

The basic one sentence explanation in the article is fair enough, but I’d like to go in to just a little more detail about the what and why. Most fluids that we’re interested in getting out of rocks (water, oil, natural gas) are locked in sedimentary rocks**. We’re used to thinking of rocks as very solid things; the fact of it is, many of them are surprisingly un-solid. There are two very significant properties to these sedimentary rocks that determines how hard it’s going to be to extract the fluid.

The first is porosity – just how much “air space” there is in a rock. (Picture here) These spaces in the rock are basically the gaps between the grains that have been cemented together to form the rock. The higher the porosity of the rock, the more of your fluid of interest it can contain.

The second important quality is permeability – just how interconnected are the spaces in the rock? For example, a rock could potentially be quite porous, but if each of the spaces in it are completely isolated, it would be impossible for fluid to flow through the rock.

Permeability is a nice quality for a reservoir rock to have. If you want to get fluid out of that rock and it’s nice and permeable, often all you really have to do is drill down into the rock and then let the pressure differential do the work for you. The fluid in the rock will be under a lot more pressure than what’s in the well, so the liquid will just move on its own. But if a rock’s not very permeable, that fluid flow doesn’t happen easily because there just aren’t many paths for the fluid to travel. Rocks like that are referred to as “tight.”

Enter hydraulic fracturing. At its most basic, you just pump a lot of water and sand down in to a formation, under high pressure. The water finds zones of weakness in the formation and fractures them further; the sand keeps the fractures open. The end result is the creation of a lot more paths through which fluid can move through the formation and in to your well. However, there’s also the addition of a lot of chemicals to the fracturing process, many of which are included to help keep the sand from clumping up and clogging the fractures that you’ve just made.

For the most part, I don’t see a lot of problems with the basic practice of hydraulic fracturing. (Not on the table for discussion at the moment: the basic practice of using fossil fuels.) It aides in production – sometimes making it possible to produce from formations that would otherwise not produce at all – and ups the amount of fluid recovery. Most of the time, oil and gas producing formations are far deeper than the water table and properly done fracturing shouldn’t intrude anywhere near it. That said, a lot of the time you’re drilling through an aquifer to get where you need to go, or more importantly, fluid spills can occur at the surface or nasty things may find a way to escape waste pits. Even if you’ve got the most environmentally conscious and careful drilling company in the world, accidents can happen and should not be ignored. It doesn’t take too many mistakes to harm an aquifer and potentially hurt all of the people who rely on it for their water.

In my rather inexpert opinion (and from the news articles I’ve read thus far) the main problem with fracturing doesn’t seem to be the process in the ground, but rather spills and waste collection at the surface. Thus, I don’t think banning hydraulic fracturing would necessarily solve the basic problem, which at this point appears to be surface safety, and would quite possibly have an adverse effect on the natural gas market***. If there’s real, substantiated concern (which there seems to be) over contamination of ground water, then the Safe Drinking Water Act no doubt has something to say about it. Though I am also forced to wonder if adding another layer of regulation will do much good if current safe practice requirements are not being properly enforced.

Side note: There’s quite the collection of links for groundwater contamination news stories at the site NoFracking.com. I used the site as a link mine to see what contamination complaints/news was out there rather than as an informational source.

* I am an intern at an oil company. My opinions are not in any way the opinions of my company.

** Some times you’ll get water out of an igneous/metamorphic rock because it’s seeped in to fractures from the surface, or from an underlaying sedimentary reservoir. We won’t worry about that here.

*** Your mileage on this may vary, depending on how worried you are about the price of natural gas versus the possibility of finding some extremely scary chemicals in your drinking water.

5 thoughts on “Hydraulic fracturing

  1. Reply Anonymous Dec 24,2009 00:37

    Do you receive any money, directly or indirectly, from the oil and/or natural gas industries?

    Also, why don’t you differentiate between vertical and horizontal fracturing, the latter being at the heart of the matter? Not until horizontal drilling really took hold did we begin to hear about all the incidents of contaminated drinking water and surface water. This is not a green issue, but, rather, it is about wanting to protect our most valuable resource: drinking water.

  2. Reply Rachael Dec 24,2009 01:19

    I am actually an intern at an oil and gas company, which I suppose I didn’t state strongly enough in my post; I will correct that now. Since I’m not an engineer I don’t necessarily have authority on this matter, but I do understand the basics of what the process is intended to do, which is what I wrote about. As it is, the basic function of fracturing doesn’t really change between vertical and horizontal well bores; it fractures the surrounding formation to allow better flow of fluids. I would guess that the main difference is that a horizontal well would require a lot more fluid, since there is a greater exposure of the formation to fracture.

    I didn’t feel the need to discern between horizontal and vertical drilling in this case because ground water contamination is a concern no matter what type of well is being drilled, since the wellbore still goes through the aquifer and there is still surface activity that can cause contamination. From the articles that I read about the contamination concerns the primary source of contamination tends to be at the surface, from spills or waste pits.

    Having re-read my post, I’ve edited the final paragraph a bit, since it was the leftover of two paragraphs combined and did not express my opinion clearly. Hopefully my position is now clear.

    I would argue that this is a green issue, since groundwater contamination not only threatens the wellbeing of humans that utilize the aquifer/surface run off, but of the environment as a whole in that area. But I also don’t tend to think that “green” is a detrimental label for an issue.

  3. Reply Anonymous Dec 24,2009 05:15

    I think you do need to make a distinction between horizontal and vertical fracturing for more than just the increased water usage.

    With the horizontal method, fractures are done over more area than the vertical method. It has been demonstrated that many times the cracking in the rocks that occurs can extend for some distance; one case I read of had a fracture that went 8000 feet. It is not always possible to control the length or direction of these fractures, so they may pose a threat to areas that are some distance away with a different aquifer depth, or an abandoned well present.

    It is also possible that more fractures could occur over time as movement in the rock occurs. That activity could open up or crack the well casing, which would then allow gas to migrate into an aquifer.

    Additionally, because a horizontal drill can extend over a greater distance, with multiple wells drilled in a single area, there is some evidence that seismic disturbance can also happen. This makes the combination of horizontal drilling and hydrofracking a very different animal than a traditional one bore, single vertical fracked well.

  4. Reply Rachael Dec 24,2009 06:26

    If you could throw some links at me for those, that’d be great.

    To be fair, this post wasn’t ever intended to be a careful examination of the issues surrounding the technique. Basically I read a news story, read another one, and noted that both had a pretty lame single sentence explanation for the process. My main intention was to expand on the short, lame explanation a little more to hopefully provide a better grasp of the basic reasons why the process is used and why it works. (Since consequences aside, it does work, and well.)

    That said, I’ve nothing against doing a follow-up since it sounds like an interesting issue, but I obviously need to know more about that particular angle. My experience with tight gas shales and horizontal drilling is purely on the geological side of things, not the engineering side.

    The cracked well casing/abandoned well bore issue definitely isn’t unique to the horizontal drills. There was a case in Wattenburg in Colorado where the ground water was being contaminated by natural gas from some nearby wells. There was an amazing video of someone that was actually able to light up the water coming out of the faucet in their house because of that; unfortunately I haven’t had any luck finding the video, because I’ve been wanting to link to it. To the best of my knowledge, the wells in that area are actually fairly shallow vertical wells, so there’s still issues to be found there.

  5. Reply Anonymous Dec 28,2009 00:30

    The tap water video is located here:

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