Fracking: the unread paper debated
- Ivo Vegter
- 15 Jun 2012 02:50 (South Africa)
The authors of the unpublished draft paper that caused a storm of headlines about the upward flow of groundwater in the Karoo and the inevitability that freshwater aquifers near the surface would be polluted by shale gas drilling, Gerrit van Tonder and Fanie de Lange of the University of the Free State Institute for Groundwater Studies, do a determined job of defending their position in the comments on my column published on Tuesday. It is worth reading those responses and some of the debate that followed. (Fair warning: do try to dodge the trolls.)
By e-mail, however, came a new and noteworthy contribution from Peter Rosewarne, team leader and principal hydrogeologist on the Karoo Groundwater Atlas project. With apologies for his delayed response to the questions I had sent SRK Consulting, which managed the research, Rosewarne weighed in on the geohydrology professor’s “U-turn”.
He says that “the team members canvassed so far do not agree” with Van Tonder, who “was a peer reviewer” and “concurred with the Atlas contents”.
Rosewarne says he is not aware of any new research that has been done since the publication of the Atlas to so dramatically change Van Tonder’s position.
“Most [research team members] disagree and are mystified by his ‘u-turn’ and haste. However, at this stage we have not seen or read the full paper.”
He adds some useful context:
“Should shale gas exploration be given the go-ahead in SA there will be a large amount of research work required, including [the land and airborne geophysics and exploration drilling mentioned in the Atlas] to obtain a better understanding of the deep environment. This will be done at a measured pace with data and results being rigorously debated and reviewed, amongst a broad team of Karoo hydrogeological experts (and others) so that a sound and defendable scientific basis is laid for the flow model(s) developed.
“We [the SRK Consulting group that developed the Karoo Groundwater Atlas] hope to be part of the team developing the understanding and conceptual model for flow dynamics in the Karoo to assist in sustainable and environmentally friendly use of natural resources.
“Much of the frenzy around this topic seems to me to be premature; if the government lifts the moratorium on shale gas exploration then there will be ample time and funds made available to carry out the necessary research to form a sound scientific basis on which to make further decisions. If the moratorium isn’t lifted, or a decision is further delayed, then end of story/opportunity.”
Another observation Rosewarne made is that the hot springs noted in the Groundwater Atlas are not saline, as might be expected if Van Tonder’s theory that they preferentially conduct water from deep saline aquifers is correct.
Michael Baker, who identifies himself as a retired member of the Society of Petroleum Engineers with extensive experience of hydraulic fracturing, addressed a number of the technical questions that the description of hydraulic fracturing by Van Tonder and his co-author, Fanie de Lange, raises.
In particular, Baker explains why, in an environment that follows modern drilling practices such as those imposed by UK regulators, it is unlikely that well-bore annuli – gaps between either the well sleeve cement and the steel sleeve itself, or between the cement and the surrounding rock – will form and create a preferential pathway for the upward migration of fracturing fluid. His comments are highly technical, but worth reading, if only to illustrate the level of scientific knowledge that exists among drilling engineers.
As his “final and jackpot question”, Van Tonder cites a paper by Tom Myers, who was commissioned by an environmental group to conduct a similar study for the Marcellus Shale in the US. This paper was not news to me, and several credible scientists have raised doubts about it.
For example, Don Siegel, professor of Hydrogeology at Syracuse University, notes several mistaken assumptions in the Myers model, including about the nature and permeability of the rocks overlying the Marcellus shale, and the flow patterns of deep groundwater itself. He concludes: “More than anything else, the public needs to know that a mathematical model of groundwater flow, such as the one prepared by Myers, constitutes only a representation of reality – it is not reality itself. Before any math model can be built, a scientifically plausible conceptual model needs to be developed. As it relates to this particular paper, Myers has developed an implausible model that predictably leads to implausible, and in my judgment, completely wrong results – from simple first principles of geologic and hydrologic understanding, let alone acceptable model development.”
This seems to square with the conclusions in the Karoo Groundwater Atlas: “...as was agreed by the workshop delegates, there is so little data available below 300 m that it is difficult to 'populate' the deep conceptual model, beyond making intelligent hypotheses. This uncertainty is indicated by the liberal use of question marks.”
Terry Engelder, the geosciences professor at Penn State University, agrees that Myers’s model contain errors that skew the results, including assuming that the pressure of fracturing will drive water away from gas-bearing shale, rather than driving it up the well. The well, of course, is the ultimate “preferential pathway”, being far more “permeable” than any other. It is designed both to sustain pressure at the fracturing stage, and prevent leakage of gas and water into surrounding rock (and aquifers) during the production stage. Any brine that comes up from deep aquifers will come out of the wellhead, as planned.
“In my view the issue is settled, which is that it can’t happen on a time scale that is important to mankind,” Engelder said, as reported in BusinessWeek.
Emily DeSantis, of New York’s regulatory authorities, makes a similar argument to my own, about why we don’t see saline water in freshwater wells already, if deep water moves up existing preferential pathways: “The high salinity of native water in the Marcellus and other Devonian shales is also evidence that fluid has been trapped in the pore spaces for hundreds of millions of years, implying that there is no mechanism for the movement of fluids between formations.”
The Myers paper seems just as far from establishing 100% certainty as Van Tonder’s draft, and likewise seems aimed more at generating simplistic, sensational headlines. Both may merit further research to validate or falsify the speculative conceptual model, but that’s all. Neither merit a declaration to the lay media that shallow groundwater pollution will be an inevitable consequence of gas drilling.
Mike Muller, a member of the National Planning Commission and former director-general of the Department of Water Affairs also commented:
Thanks Ivo for digging this up – I had seen Gerrit van Tonder’s comments, which made little sense as reported, and wondered about their basis.
We have a real problem with the abuse of science by lobbyists in this area and need to keep documenting the detail – one benefit of online media is that editors don't get tetchy about it.
From my experience in a previous life as DG of Water Affairs (and a little of my own MSc research) I can confirm that the dolerite intrusions are targeted by people who are drilling for water in the Karoo. If they were associated with an upwelling of saline water from deep formations, that would not be the case. There is thus practical evidence that saline flows along dolomitic pathways have not generally been significant, even if there are a few hot springs.
One related dimension that you don't pick up is the possibility that, because of the history of dolerite intrusion into the shales, any gas initially present may have long been dissipated – “baked off”.
That’s why we need to have some test drilling. This fracking debate may well be a lot of hot air about a resource that's not there. But wouldn’t it be nice to know what our options are?
As for the management of the wastewater, that is a relatively simple technical problem, which will be a lot easier in the Karoo (hot, dry lots of evaporation and limited and predictable flood paths) than elsewhere. For Gerrit to say that organics can’t be removed by treatment is plain nonsense!
And of course the fluids at 3,000 metres are under pressure. That’s how the gas, if it’s there, is going to get to the surface. So for Gerrit to raise fears about an “Old Faithful” type geyser is descending into the really rather unscientific scare tactics.
If I was a Karoo farmer (as opposed to rich retiree wanting to privatise the natural amenity), I would be negotiating with one of the prospecting companies to improve my farm’s roads and communication infrastructure and a build a properly designed and instrumented well-field to provide water for the initial fracking that I could use afterwards to expand my operations – a couple of hectares of irrigation will always be useful.
Any offers, all you Karoo landowners? I could fancy a retirement as a fracking farmer...
With this level of opposition among scientists and others who ought to be in a position to know, it seems rash to run to the media with a claim to be “100% certain” of an upward flow gradient that would make pollution of Karoo groundwater aquifers inevitable, especially since Van Tonder was in a position to know the simplistic sensationalism such a claim would cause.
In last week’s Farmer’s Weekly, Van Tonder is quoted as saying polluted water from deep levels could reach surface aquifers in as little as “months or even weeks”. In another article of which I have seen a draft, due to be published in next week’s edition of the same magazine (full disclosure: I originally said “this week” in the comments, but have since been corrected by its author, Roelof Bezuidenhout), he will be quoted saying “20 years to thousands of years”. This is not only a rather large margin of error, but it is a blatant self-contradiction, which makes everything else Van Tonder says suspect.
It certainly does not support the headlines in the popular press, nor does it support the continued imposition of a moratorium on shale gas exploration. The longer we postpone the necessary research, the more gas will be on the world market from other sources, and the less likely it becomes that the vast Karoo reserves will benefit South Africa. DM
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