INNOVATION March-April 2012

f ea t u r e s

How Vulnerable are BC’s Shallow Aquifers

to Shale Gas Extraction?

Dr Richard Jackson PEng Alan Kohut PEng

Because of certain failures in the USA associated principally with poor well completions, shale gas development has been criticised for contaminating shallow groundwaters. However, if best industry practices are followed, such groundwaters should remain uncon- taminated. We consider this issue as it relates to Northeastern British Columbia and discuss the need for adequately charac- terizing the baseline groundwater conditions to enable rapid resolution of any potential disputes. Such information will provide the necessary knowledge that leads to better-informed decision making, improved groundwater management practices, and robust science-based guidelines. The protection of BC’s shallow aquifers during shale gas development requires nothing less. Introduction The development of shale gas in Northeastern BC promises to create a major industry that will sustain exports of natural gas to elsewhere in Canada, the USA and Asia. The MIT Energy Insti- tute reported the recoverable gas in the Montney Shale and the Horn River basin as 230 trillion cubic feet (TCF) and 154 TCF respectively, while Canadian and US annual consumption are roughly 3.5 and 23 TCF, respectively. The undiscovered, recover- able gas in the Barnett shale of Texas and the Marcellus shale of Pennsylvania was estimated by Bruner and Smosna of URS Corporation in 2011 as 39 and 50 TCF, respectively. Therefore the potential of the two BC shales—mostly confined beneath the boundaries of BC—is immense. This paper discusses the vulner- ability of the shallow groundwater resources in Northeastern BC to such development and what future hydrogeological research is needed for their protection and management. Shale Gas Extraction Innovation in shale gas extraction over the past 20 years has blended horizontal drilling, hydraulic fracturing (fracking) and micro-seismic testing resulting in a much improved approach to exploiting such reservoirs, tight-gas sands and other unconven- tional gas resources. Figure 1 shows a horizontal shale gas well and the general scheme of hydraulic fracturing that must be fol- lowed by injection of fracturing chemicals and propping agents carried in a water or propane/butane stream. Production of gas occurs after the injected fluid—flow-back fluid—is extracted.

Figure 1 . Schematic of a horizontal well with induced shale fractures and shallow aquifers. Image courtesy of Apache Canada Ltd.

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