Environmental effects of hydraulic fracturing
A good deal of public debate and media focus on the environmental effects of ‘fraccing’ has led to a groundswell of grass root movements opposed to both hydraulic fracturing and the development of unconventional petroleum resources in general. The flow on effect has politicised the regulation and management of onshore petroleum exploration in Australia, and in some states bans or moratoria have stifled exploration, citing environmental issues. Two of the key concerns raised are induced earthquakes, and contaminated water supplies due to migration of fracturing fluids.
Michael Blackam, a Senior Principal with Coffey, has undertaken a review of the science surrounding hydraulic fracturing, and in particular the potential for these impacts to occur. The review helps people gain insight into the science and mechanics of the technique, and looks at the documented findings of other studies.
Assessing the risks of hydraulic fracturing
Hydraulic fracturing has been widely adopted in the oil and gas sector for well stimulation, and has been applied to conventional petroleum reservoirs for more than 65 years. Although the physics are complex, the review shows that the technical issues are well understood and tested in both theory and practice. Historical evidence gained over a long period of widespread application of hydraulic fracturing in the petroleum sector demonstrates a very low risk of environmental impact directly arising from field application of the method.
The review finds that risks due to hydraulic fracturing induced earthquakes are low, with few seismic events of any note being attributed to hydraulic fracturing, despite the many thousands of well stimulation events conducted. In contrast, induced seismic events attributed to other human induced activities, such as mining, reservoir construction and waste fluid injection, are seen to have greater magnitude.
The potential for contamination of water supplies from hydraulic fracturing fluid is clearly the single greatest public concern surrounding hydraulic fracturing, and the development of unconventional gas in general. In particular, unsubstantiated claims abound that hydraulic fracturing events have led to contamination of shallow groundwater aquifers and surface water supplies.
The review considers the potential mechanisms for fluid migration, and shows that the risk of transport of hydraulic fracturing fluids to surface water or near-surface resource aquifers, arising from out of zone fracture development during well stimulation, is low, and that claims to the contrary are inconsistent with the evidence.
Read the full review.