To Frack Or Not To Frack?: Meeting the Environmental Challenges of Shale Gas DrillingAdd bookmark
There is now no doubt that the discovery of shale gas in the US has revolutionised the country's energy industry, enabling it to reduce its dependence on foreign imports and secure its domestic supply for the foreseeable future.
The Marcellus Shale target is one of the fastest growing shale gas producing regions in the country. In 2007, just under 100 drilling permits were granted in the region. In the first eight months of 2010 this figure increased to 2,108.
Michael Arthur, co-director of Penn State's Marcellus Center and professor of geosciences, said: "We expect that the uptick in Marcellus well drilling activity will continue, given the high production rates being seen in the wells and the relatively low cost to develop this gas resource. "Even with the low natural gas commodity pricing, drilling in the Marcellus can still be profitable for efficient companies," he added.
However, for shale gas to become accepted by members of the public and legislature in states where drilling is taking place, there are environmental questions that need to be answered, particularly in relation to water quality.
Hydraulic fracturing, also known as fracking, is one of the key techniques which has allowed for the release of the natural gas stored within the shale plays, and as interest in the Marcellus Shale play increases, so will the use of this technique. It involves injecting three million to five million gallons of water, combined with salt and other additives, at high pressures into the rock formation to release the gas. Wells are drilled either vertically or horizontally, and can extend several thousand metres from the wellhead on the surface.
Much of this fluid is acquired from local groundwater supplies and, according to the Environmental Protection Agency, between 15 per cent and 80 per cent of this is the recovered, depending on the site. There are concerns that the process of hydraulic fracturing could have a detrimental effect on drinking water because of the additives it contains and also the natural minerals it could release from surrounding rocks.
Water which has been used for fracking, known as flowback, must be treated before it is released back into the environment. However, in order to cut their environmental impact more companies are choosing to reuse this liquid for further hydraulic fracturing. Research conducted by Penn State University found two-thirds of the flowback from the Marcellus region which was returned to the surface within 30 days of drilling was reused by companies, the Pittsburgh Tribune-Review reported.
Tony Gaudlip of Range Resources, explained: "We do not need crystal clear water to use as a base fluid for fracturing. "We do not need to treat the water at all in order to get good production - no distillation, crystallization, reverse osmosis, nanofiltration, etc. That's all unnecessary to meet new downhole requirements," he added. Another way to reduce the environmental impact of flowback could be portable, on-site treatment systems, like that recently developed by Aquatech International.
Field testing of the system, which is based on technology which has already been used at more than 1,000 sites worldwide, is currently taking place. By treating water at the well site, the number of trucks needed to carry the fluid to treatment plants would be dramatically reduced. Devesh Mittal, Aquatech's vice president, described the technology as a "game changer", telling the Observer Reporter: "It is a huge set-up at the well pad, and logically it is the best place to do the treatment."
Such advancements, however, are unlikely to quiet those who firmly believe the extraction of shale gas will have a detrimental effect on water quality, no matter what steps are taken.
Wenonah Hauter, executive director of Food &Water Watch, was commenting following the reintroduction of the Fracturing Responsibility and Awareness of Chemicals Act in the House of Representatives and the Senate when she said: "Federal oversight of hydraulic fracturing is almost non-existent."
"A national, permanent ban on fracking would erase these doubts and protect drinking water from a reckless, poisonous practice. Let’s end all hydraulic fracturing in the US," she said. Introduced by Senator Bob Case, the bill calls for greater disclosure of the chemicals used in fracking, which is intended to protect water quality. Although the bill is still in the early stages, it will be up to oil and gas companies to convince the public and the government that they can balance the opportunities of shale gas production with its environmental challenges.