Gasquake

March 3rd, 2011
Email This Post  Print This Post  

There is no humour in the deadly earthquake that his Christchurch last month. New Zealand, for all its beauty, is in a seismically active region. Tectonic plates are colliding, with fatal consequences.

No one is looking to blame the Kiwi quake on anyone, save perhaps the Creator. Not so the apparent recent increase in seismic activity in Arkansas, including a magnitude 4.7 earthquake last week. Some news reports were quick to link the earthquakes to recent oil industry activity. Specifically, they cited injection of water produced with natural gas and reservoir stimulation (“fraccing”) as possible causes for the quakes. One geologist speculated that the injected water was lubricating faults and easing their movement.

This is interesting given that, some years ago, industry opponents in the Peace River district of Alberta were claiming earthquakes were caused by removal of fluids from formations, rather than injection of fluids. Ironically, there is now massive unconventional gas exploitation underway in the Peace region that involves extensive fracturing of formations and injection of high-pressure water at depths of several thousand metres. To my knowledge, there has been no incidence of earthquakes there.
As one geologist
pointed out, the earthquakes in Arkansas seem to arise from between one and three miles below the surface. This is significantly deeper than industry is injecting fluids and fracturing rock.

Regardless, the apparent increase in the frequency of quakes in Arkansas and elsewhere must be taken seriously. If it can be proven that industry activity is somehow changing the Earth’s stress regime at depth and causing tremors, then that needs to be addressed. It is, as always, regrettable that the public and media rush to blame industry and maintain an attitude of guilty until proven innocent when it comes to industry activity.

All this underscores, yet again, the imperative that the oil gas industry tirelessly represent itself to the public and get facts out.  Industry spends hundreds of millions of dollars monitoring the seismic character of their fracturing programs.  These show that the effect of the induced fractures radiate on a scale of tens of metres from the well-bore, rarely more than 100 metres. That is, not thousands of metres.

As I was writing this I unwittingly waded into the whole dispute around hydro-fraccing that has erupted in the U.S. Part of the controversy revolves around the film Gasland, yet another attempt to enflame the public about environmental evils perpetrated by industry – specifically, the contamination of ground water through fraccing of gas formations. So effective is the anti-industry grapevine that, according to one friend of this blog, fear of shale gas development has spread as far as eastern Europe.

My impression is that, as with the growing pains in the early years of coal bed methane development, the filmmaker and others are taking a few cases where there may be legitimate, industry-caused problems and implying that there are catastrophic environmental consequences. Coal bed methane has been exploited for more than 20 years and, to my knowledge, there have been no such consequences. Anecdotally, I am aware of instances where industry disposed some produced water at surface when they probably shouldn’t have, but such cases were early on, and rare.

Similarly, when there are thousands, or tens of thousands of fracs done per year, and you have perhaps a handful of possible problems with landowners and their water sources, you should just deal with them. However, I imagine that industry fears a scenario where for every legitimate case where they pay for someone’s groundwater problem, they have thousands of his or her neighbours lining up with their hands out demanding compensation for a non-existent ill.

So as with the increased quakes, is it possible that some landowners might have their water wells affected by fracs thousands of metres below the surface? My gut tells me never say never. But will shale gas development wreck the groundwater in vast parts of Pennsylvania, New York or Colorado? Unlikely. But that’s not news is it.

Blogmarks BlogLines del.icio.us Digg Facebook Google Google Reader Magnolia Yahoo! MyWeb Newsgator reddit SlashDot StumbleUpon Technorati
By John Weissenberger
Category