One of the key topics at the moment regarding the future of global energy revolves around the extraction of gas from shale formations through a process known as hydraulic fracturing, or fracking. There is a vigorous and strongly polarised debate between pro- and anti-fracking campaigners, based around environmental concerns. Many of the issues raised though are just ill-informed crap. The media are partially to blame for this, as well as the ridiculously naff Gaslands viral ‘documentary’, ironically so as it is devoid of any actual facts.
The Royal Society and Royal Academy of Engineering (UK) have recently released a review of environmental risks associated with fracking, and concluding, despite it being in no way their position to, that shale gas extraction should go ahead in the UK. The Geological Society recently held a shale gas briefing meeting where gas extraction was discussed purely in a geoscientific context. What these both provided, adversely to so much of the material out on the interwebz, is evidence. What they both seem to at least imply, is that fracking CAN be done. What they don’t address is the question of whether it SHOULD be done, in alignment with the plans to decarbonise UK industry and forge a Green Economy in the UK to mitigate climate change. Despite this, the debate between many parties continues about environmental risks. Although not all have been addressed, many of the ‘big ones’ have, and subsequently demonstrated to be non-issues.
[youtube http://www.youtube.com/watch?v=e9CfUm0QeOk]One of the prevalent issues still discussed is groundwater, or aquifer, contamination by fracking fluids or fugitive emissions. This is largely stimulated by the notorious Gaslands video, although a counter-operation is in place by Frack Nation after it was discovered the producer (Josh Fox) was a douche (see video above regarding just how clueless this chap is). A new paper has gone into quite detailed geochemical analysis in the region of Gaslands’ origins, Philadelphia. Fracking in the Marcellus Shale has been purported to be the source for substantial volumes of methane and other dangerous contaminants, and this has largely been gobbled up by anti-fracking campaigners and used as a tool to fight against fracking operations. Another paper now in press analyses the hydraulic connectivity and can be found here for free, which complements the one discussed here quite nicely. The paper by Nathanial Warner and others is also open access fortunately, so the authors and PNAS get a big thumbs up there.
The team used a pretty impressive sample size, taking 426 shallow groundwater samples to geochemically analyse. These were sub-divided into four types based on the volume of total dissolved solids, which were recognisably meteoric or from deep underground in origin. Spatial delineation of sample types with respect to fracking wells allowed correlations between geochemistry and distance from fracking sites to be discerned.
‘Type D’ waters had a geochemical fingerprint resulting from mixing of meteoric waters and deep brines. The study found no geospatial relationship exists between these saline waters and shale gas developments, implying it is highly unlikely that any shale gas related processes caused contamination, and that the geochemistry of aquifers results from naturally occurring processes. Strontium isotope ratios confirmed, however, that the saline component of the fluids is from the Marcellus Shale Formation.
Natural tectonic structures have been widely documented in the Appalachian Basin that allows migration of deeper fluids into near-surface aquifers. Apparently, this migration is related to deformation during the Alleghenian Orogeny resulting from natural fracking from catagenesis (fracturing from over-pressurisation of natural gases). The resultant increased connectivity (permeability) plausibly increased the hydraulic gradient and allowed fluids to flow passively to zones of lower hydrodynamic pressure (i.e., nearer to the surface). This also implies contamination from well-leakage highly unlikely based on the different chemical signatures resulting from different contamination time scales.
The main finding is that, get this, pathways unrelated to shale gas extraction through fracking previously existed connecting shale gas formations to shallow water aquifers. Salinisation of groundwater is not correlated with drilling localities, and is entirely consistent with baseline chemical levels before any fracking began. What they do show is that there is some form of geostructural or hydrodynamic regime that allows mixing of deep shale fluids with shallow aquifers. Contamination risk has always been present in Pennsylvania, fracking just caused people to take an interest in it and find something to blame. Future research is, of course, needed as is live monitoring of hydraulic connectivity, something that has been employed by the oil and gas industry for a long time now. Of course, stricter regulations never hurt anyone either, and in the UK, these are under revision as part of the ‘can we frack?’ initiative. The answer, is yes, yes we can. Can we do it without short-term environmental damage? Yep, with a stringent regulatory regime. Should we extract shale gas? No one seems willing to answer that one properly yet, but I think we all know the answer really.