An ear to the ground to reduce impacts of fracking

Geophysicist Mirko van der Baan has an ear out for microseismic activity near oil and gas production sites.

Lucas Habib - 24 July 2013

(Edmonton) Hydraulic fracturing, better known as fracking, is getting an awful lot of press these days. It's been lauded for opening up unconventional gas reservoirs to development-the reason that some are predicting the US will achieve energy independence in about 20 years. But it has received plenty of criticism as well for negative environmental effects-clandestine chemical compounds being pumped into the ground where they could be affecting groundwater reservoirs. University of Alberta researchers are working to reduce some of the negative outcomes of fracking by helping industry to minimize unintended consequences.

Geophysicist Mirko van der Baan (physics) is a great listener. For 15 years, he's been using microseismology to eavesdrop on oil and gas production deep beneath the ground. When energy companies use hydraulic fracturing, they inject large quantities of highly-pressurized water and chemicals into the earth to shatter the rock, creating permeable pathways for gas to trickle back to the well. All that pressure can also affect the geology of the remaining rock through compaction and shearing, which can have implications for a gas field's future production.

Van der Baan, though, has helped develop a technique to monitor these "miniature earthquakes" happening underground and to determine how they change the geology and mechanics of the reservoirs and rock surrounding them. Along with collaborators from industry, the University of Calgary, and a team of 30 graduate and undergraduate students, van der Baan is conducting experiments that he hopes will increase the energy industry's efficiency.

In August, the team installed geophones-miniature versions of the seismographs used to monitor earthquakes-into a borehole on a ConocoPhillips wellsite a few weeks before hydraulic fracturing began. Since then, they have been monitoring microseismic activity during fracking, after fracking has ceased, and before it began (natural background microseismic activity). "It has really let us see how the whole cycle works," says van der Baan. He hopes that once they understand the process, they will be able to make key recommendations to industry on how to optimize water usage-it's possible, for example, that far less water could be used to achieve the same results. Van der Baan also hopes that their results will help optimize horizontal well spacing on the landscape. "We hope to predict how far from the wells a reservoir will be drained, which may result in a reduction in the number of wells," he says. "Geophysics puts a lot of emphasis on critical and analytical thinking-we need people from many different disciplines who are interested in every aspect of this research."