Hydraulic Fracturing: Images from Under Ground

My tongue-in-cheek comment on the language of hydraulic fracturing was intended to get at the ways in which metaphors and images can affect – and sometimes skew – our understanding of risks and responsibilities.

This effect can work in any direction, for or against any particular position, and it can be especially pronounced when the problem situation within which people are making decisions – and disagreeing with one another over what decisions to make – are not well understood.

One theme that emerged early in our first workshop on hydraulic fracturing was that nearly every available image of hydraulic fracturing is inaccurate in ways that may exaggerate or, at least, misrepresent the risks involved in the process – and this is true even of images on websites of those who should know better, and on websites of organizations generally favorable to the use of hydraulic fracturing in oil and gas extraction.

One of the students on our project team came across an especially egregious example of the type, an image used in the film, Gasland:


There are at least three problems with the image:

First, the scale is way off. In fact, it is quite literally a mile off, given that the horizontal part of the borehole would more typically be 6000 feet or more underground, while ground water is generally found much closer to the surface.

Second, the rock is represented as a homogenous substance rather than as consisting of strata of different kinds of rock, as would be the case in regions in which hydraulic fracturing is possible. Shale formations are more typically found sandwiched between layers of impermeable rock, and there may be many such impermeable layers between those being “stimulated” and the surface.

Third, the fractures from the horizontal borehole are shown as jagged scars propagating all the way up to and into an aquifer, but shale doesn’t fracture that way. Other images, even from reputable sources, show cracks radiating and intersecting like shattered glass, which is really no better as a representation of how shale behaves. Stimulation instead results in planar fractures, perpendicular to the borehole and limited in extent; they do not propagate very far, and certainly not through 6000 feet of permeable and impermeable rock up to the groundwater!

Contrast the image above with another image, one that appeared in the magazine Manufacturing Engineering:


Here, the scale and the stratification of rock are sorted out, to some degree, within the limits of a schematic diagram. The borehole is wider than it should be, using the scale of the rock strata, and the objects on the surface are larger than they should be. More important, the cracks still appear, on closer inspection, to be branching like trees, though at least they do not propagate very far.

The point I would stress from the first day of the first workshop is that there are risks from hydraulic fracturing, but not the ones shown in the first image, and most likely not the ones that seem to haunt the public imagination.

I would also emphasize that the engineers involved in oil and gas drilling are quite good at identifying and sizing up risks: we came away from the afternoon session on the first day with quite a comprehensive list of things that can go wrong, with a sense of the probabilities and the uncertainties surrounding each.

The mechanical integrity of well casings near the surface – shown in the inset in the second image – deserves and receives a lot of attention from industry and from regulators. Likewise the handling of waste water from the stimulation process remains an issue

Of the risks that have been recognized, many of them have been the focus of mitigation efforts, whether by industry practice, public regulation, or both. For example, both of the above images are out of date in reference to more recent drilling sites, where industry practice has shifted to storing waste water in tanks rather than in pools.

This is not to say those risks have been eliminated, or even that they have been mitigated to a satisfactory degree.

One risk on which no one seems to have an especially good handle is the possible “communication” between a horizontal bore undergoing stimulation and a nearby abandoned well, perhaps unplugged and without a casing at the surface, that might be subject to methane migration.

On this point, the second image could be said to be too tidy, as it excludes features like boreholes from an earlier period of oil and gas extraction that might pierce those politely horizontal and unbroken strata.

As one of the engineers at the workshop pointed out, risk is simply a reflection of the fact that nature is not homogeneous.

Here, though, is the ethical point of this: even if all risks could be identified, and even as industry and regulators alike struggle to get a handle on them, there is the fraught question of what risks are acceptable, and what degree of mitigation is satisfactory, and to whom . . . but I’ll have more to say about that in tomorrow’s post.

I would simply suggest that, in deliberating about acceptable risk, we should be attentive to and wary of the ways in which language and images can shape or even skew perception and understanding, one way or another.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s