Fracking – Safe or Not?

There has been a lot of buzz lately about stimulating production from gas and oil wells using the relatively new technique of hydraulic fracturing — fracking, fraccing or fracing for short. Most of the new natural gas wells drilled in this country rely on fracking to yield economically attractive quantities of gas, especially in the booming shale-gas drilling plays unfolding around the country (Barnett, Marcellus, Haynesville, Fayetteville). Shale-oil drilling (not to be confused with oil shale) is the second wave that’s building fast (Niobrara, Bakken, Eagle Ford). These so-called “unconventional” gas and oil targets were bypassed for years until advances in horizontal drilling and fracking provided the key to unlocking these significant gas resources. Now they are becoming the main focus of drilling activity in North America, affecting many residential and even urban areas where drilling was once considered inconceivable.

Natural-gas wells on public land in the Jonah Field of western Wyoming. Fracking is routine for most gas wells drilled now in the U.S. Photo courtesy EcoFlight.

Recent highly publicized drinking water contamination incidents linked to gas drilling, and the popularity of the documentary film Gasland (can you light your tap water on fire?), have raised the public profile of this game-changing drilling process. The U.S. Environmental Protection Agency is studying the safety of fracking. Congress is holding two hearings this week, in the House and in the Senate, to try to get some answers. No doubt many of the problems stem from the mundane details of drilling that can plague any complex construction job: bad well design and construction, ill-advised shortcuts, and – the leader of the pack – poor cementing.

Industry wants us to believe that if we just fix those problems then fracking can be done safely. Disclosing the chemicals used in fracking at each drilling site, so homeowners know what to test their water for, would be a good start.

Tanks for handling fracking fluids at a new Marcellus Shale natural-gas well site in northeast Pennsylvania. Photo courtesy J. Henry Fair.

But we wonder if hydraulic fracturing is intrinsically unsafe, even if the well design and construction is totally by-the-book. Here’s why: fracking works by levering open fractures in the rock, and propping those fractures open with sand (or synthetic microbeads). Tectonically “open” fractures, that are aligned parallel to the regional stress field, are most susceptible to being pried open. If a frack job intersects pre-existing open faults or other natural fractures in the bedrock — especially vertical fractures that can span multiple geologic formations above and below the target zone — how do we ensure that fracking fluids don’t migrate in unpredictable ways via these natural flowpaths?

Smart drillers don’t want to lose all their fracking fluid into a single fracture or fault: it’s expensive, a waste of time, and doesn’t accomplish what they want. But avoiding those features requires doing borehole imaging studies on the well to identify and map them, which also costs time and money. It’s not hard to imagine a driller weighing the expense of borehole imaging surveys vs. the risk of performing an ineffective frack job.

We know just enough about this to raise a few questions, and would appreciate some real experts weighing in by commenting on this post:

  • What do companies do to avoid the undesired result of fluids migrating out of the fracking target zone?
  • What actions to avoid this result are required, and how are they verified by regulators?
  • What actions are voluntary, and how commonly are they used?

Thanks in advance for sharing your expertise on this important issue!

16 replies
  1. josephpsmith says:

    One thing that companies do is monitor frac jobs with a process called microseismic. Basically, in a well that is adjacent to a well being fractured, listening devices are placed along the entire length of the well bore. The cracking of the rock can then be recorded. Specifically, how high up the frac grows. Then adjustments can be made (real time) to the amount of horsepower being used so that the fractures do notr grow up too high.

  2. John says:

    Thanks Joseph – I've heard of that technique. Any idea how commonly it's used on fracking jobs? How close does the adjacent well have to be for this technique to work?

  3. josephpsmith says:

    It's use really depends on the size of the company. Most publically traded companies do it. At least initially to dial in their horsepower requirements. Less horsepower equals less expense and allows you to establish a base line for say a given county or township. Some really large companies do it on almost every well so they can monitor every job real time.
    I am aware of it being used a mile or so from the well being frac'd but do not know the maximum effective distance. The closer the better though because it picks up noise from traffic, trains, etc. There is some really good data one of the companies that provides this service has collected from the Barnett. I saw the paper once but can't recall the author. I think the company was Pinnacle and they had data from approximately 2,000 frac jobs or stages in the Barnett. Ah, found the link the graph is telling in my opinion. At least for the Barnett. Would be nice to see these for all the shale plays.

  4. John says:

    Thanks – those charts do seem to vindicate fracking, at least for the data they represent. Some of the induced fractures reached almost 2000' above the perforated interval in the well – shouldn't be a problem if you're at least a few thousand feet below the aquifer.

    For our readers' benefit (and mine) – what's your experience with the industry? You must have been around a bit to know that most publicly traded companies routinely use microseismic monitoring.

  5. josephpsmith says:

    I am a Geologist with an MSc and 11 years of industry experience. I am no industry shill but feel the fracking debate is hyperbole, mostly. As you probably know, there are two types of natural gas; Thermogenic and Biogenic. Biogenic gas is gas produced by bacteria that live in fresh ground water and eat organic material found in shale and coal. It is the reason you have gas in underground coal mines. Thermogenic gas comes from organic material in shale and coal being buried deeply enough and heated enough that the organic material is first converted to oil and then gas. The point is that the two types have very different geochemical properties (fingerprints) and very cheap inexpensive tests can readily differentiate the two.
    I am glad people are concerned and asking questions, they should. Industry has never done a good job in attempting to explain its practices. However, the real environmental concern should be, in my opinion, surface water and erosional issues associated with road construction, spills around tank batteries, etc. No one talks about those but if you look at the violations in PA, see link, most are associated with improper discharge at surface, erosion, failure to dispose of residual waste properly, etc. Companies should be spanked, and hard, for these offenses but it has never really been part of the shale gas/fracking debate. It's not as emotive. I love the sight, keep it up.

  6. John says:

    Thanks again Joseph for this perspective, and the link to those violations in Pennsylvania. I agree that the "normal" pollution incidents related to drilling don't get much attention and cumulatively are the bigger pollution story. But even if the drinking water contamination incidents are relatively rare, they are of much higher consequence – especially if it's your drinking water at stake.

    Thanks for participating!

  7. John says:

    Thanks Adam (were you actually at the SouthWings fly-in?). The issue of climate impact of natural gas is critical: many are promoting greatly expanded use of natural gas to generate electricity and run our cars and trucks, as an energy "bridge" to a future of climate-friendly renewable power (biofuel, wind, solar, tidal, etc.). But there's not much data on the accidental and incidental "fugitive emissions" of methane — a potent greenhouse gas — during exploration, drilling, completion, production,transmission, storage and distribution of natural gas. There are leaks at every point in this system (and plenty of lost product that would otherwise be sold for good hard $$).

    The recent, controversial Cornell study in your blog indicates that the climate impact of natural gas produced from shale (Marcellus, Barnett, and other hot "shale-gas" plays around the country) could be as bad as, or even worse than, burning coal, mostly due to these fugitive emissions.

    Even industry, in attacking this study, admits we need better data on the fugitive-emissions problem. Before we commit as a nation to decades of accelerated drilling and natural-gas consumption as a way to ease our climate problem, we'd better do our homework.

  8. John says:

    Thanks Marge, and thanks for that link. Carl is a good writer and always brings some interesting perspectives, and he does so in this piece.

  9. D.G. Worley says:

    Nice Blog John!

    Excellent questions regarding the fracking process and possible consequences of groundwater contamination.

    Following the EPA's recent emergency order against Range Resources, citing methane contamination of two Parker County TX water wells, which the EPA blamed on Range's natural gas drilling, I suppose I've heard it all. From the operators, to those who would silence their drill bits, the "war of words" rages on.

    I'm no expert, but certainly enjoy both sides of the discussion.

    I encourage you and your readers to visit my blog "Barnett Shale Drilling Activity" at

    I focus mainly on the Barnett Shale, but encourage comments on all shale plays, and welcome input from both sides of the fence.

    D.G. Worley

  10. John says:

    Thanks DG, glad you stopped by – your blog looks like a good source of info, both pro and con. I also like The Oil Drum for a broad range of good technical info and commentary – mostly very civilized and thoughtful – on energy and drilling (

  11. D.G. Worley says:

    John – I am definitely pro-drilling. I just visited the website. Appears to be a good site, with a large following. I see where they used a picture credited to my blog site. I am trying to drive more traffic to my site and it looks like the oildrum has a number of members. Maybe they would consider a link to my site under their "BLOGS" heading.

    The following page on their site links to a post on my blog regarding the Day Kimball Hill unit:

    I would also like to include a link to your blog on my site. Kindly send some folks my way, and I will do the same for you. Thanks for your input and information.

    Take care,

  12. John says:

    Dennis – I'll encourage folks who want to get the pro-drilling perspective to visit your blog as well.

    My position is we're definitely going to be drilling a whole lot of new wells in coming years for gas and oil, but we could be and should be doing a much better job protecting other property rights, minimizing the risks, and avoiding or repairing the inevitable environmental degradation. We have the know-how and technology to do drilling a lot better, but it usually costs more money in the short term, and if for-profit businesses aren't required to spend that money then we can't really expect them to.

    A good example of this is the Jonah Field gas development in western Wyoming, on public land. When drilling began in the mid-1990s industry had well-established directional drilling technology that would have allowed multiple wells to be drilled from a single wellpad. But directionally drilled wells cost more (10-15%) than vertical wells,and the BLM didn't require industry to minimize their surface "footprint", so Jonah drillout happened with mostly vertical wells, very closely spaced. This resulted in about 10 times more surface landscape destruction than was necessary, in a climate where landscape restoration has proven extremely challenging. I blame the state and federal government for allowing that to happen, not industry. The heartbreaker is that an industry analyst told me that in the long run, over the productive life of the field, directional drilling is often more profitable than vertical drilling because so much less infrastructure needs to be built, maintained, and ultimately reclaimed.

    This industry provides good jobs, much-needed economic activity in hard-hit places, and a product that still powers our nation. The industry spends hundreds of millions of dollars per year ($200 million last year alone) getting that message out the public and to policymakers in every way imaginable: sponsoring community and sporting events, lobbying and contributing to election campaigns, continually advertising in print, on TV, on the radio.

    This is money that could be spent investing in improvements to drilling safety, land and water restoration, pollution minimization, fugitive emissions capture, alternative energy development, because this industry also causes significant damage to air and water quality and wildlife habitat, and routinely infringes on the rights of citizens to enjoy their property and to make a living by ranching, fishing, tourism and recreation. And, when used as directed, oil and gas are measurably altering our climate and acidifying our oceans, with tremendous uncertainty in how it all will play out. The folks who work to get that information out to policymakers and the public are overwhelmingly outspent by industry.

  13. D.G. Worley says:

    John – My stance on pro drilling does not mean anti environment. I have heard your views expressed by many. Safety should be paramount in any industry.

    In the quest to explore and produce our natural resources, protection of our air, water and property rights will always be an issue. Reform and regulations will obviously be an integral part of that discussion.

    As long as drilling continues I welcome input from those expressing their first amendment rights.

Comments are closed.