An interesting report coming from the University of Texas on the environmental impacts of shale gas development:
The full report is over 400 pages long, so I'm not going to claim I've read it cover-to-cover. In fact, I've only read the summary (which is still 50 pages long). However, based on what I've seen of it so far, and what the twitter-sphere is saying, there are a couple of points that I feel like talking about.
The principal conclusions are that there have been water contamination issues related to shale gas. However, there has been no evidence whatsoever that these issues have been caused by the hydraulic fracturing process in itself. We can track the formation of fractures and the migration of fluid during fracking (see the video I posted here), and on no occasion has there been evidence that fractures have migrated out of zone to impact on freshwater aquifers sited 1000s of feet above the fracturing zone, nor intersection with pre-existing natural faults/fractures that would permit upward fluid migration. Crucially, there has been no evidence of fracturing fluid additives being found in drinking water aquifers. If fluid has been migrating from fractures into freshwater aquifers, I'd expect to see fairly distinctive evidence of the chemical additives used in fracturing, and we haven't.
That's not to say that there haven't been problems, however. Once the well has been fracked, some of the fracturing fluid flows back up the well to the surface. This flow-back water must be collected and disposed of accordingly (either at treatment plants, reinjected into deep lying saline formations, or recycled for use in future frack stimulations. This is little different to many conventional oil and gas gas fields, where the produced hydrocarbon comes up the well mixed with a certain percentage of water. This water is usually saline, and may contain certain undesirable elements, such as arsenic or barium, and so must be disposed of appropriately. This is nothing new for the oil and gas industry.
Furthermore, once the flow-back fluid has been produced, the gas begins to flow. If the steel casing that lines the well is not cemented in properly, there may be gaps through which gas can flow up the side of the well, and then into overlying formations. Equally, if the casing is damaged, any holes with allow gas to flow out and into overlying formations. Again, this is a common problem in the oil and gas industry (as far as I'm aware, the Deepwater Horizon explosion was caused by so-called annular flow up a poorly cemented well).
It is in dealing with casing and cement to prevent blow-outs, casing damage and annular flow, and in treating and disposing of flow-back fluid properly, that the shale gas industry appears to have fallen short. It doesn't surprise me to hear that in some cases flowback water left in pits on the surface may have begun to leak, causing water contamination problems.
So the overlying moral to this story is that there's nothing inherently bad with hydraulic fracturing as a process. There are the usual issues common to all oil and gas extraction. We know how to deal with them, but to do so costs time and money. The key is that we put appropriate regulations in place that force operators to spend the time and the money. The underlying cause, I suspect, is that many of the shale gas developers are relatively new on the scene, and may not have the expertise of a BP, Shell, or Schlumberger, nor the man-power and finances to avoid the temptation to cut a corner or two. With the right regulation in this country, (and we have a good track record for this post Piper-Alpha), we can ensure that shale gas development in the UK does not experience the same problems we've seen
in the US.