Natural gas exploration and development in northeast B.C. require large volumes of water. This water is needed for a process called hydraulic fracturing, or fracking, which is used to access the natural gas locked within tight shale rock reservoirs. This process releases the gas and/or oil by creating spaces in the otherwise tight reservoir that allow the gas to flow.
In utilizing large volumes of water to access shale gas, large volumes of produced water are created and have to be disposed of and stored in a safe and sustainable manner. To ensure no contamination of drinking water, these produced waters must be injected into deep aquifers known as disposal zones. In the ongoing effort to foster responsible development of B.C.'s natural gas resource, Geoscience BC collaborated with the BC Oil and Gas Commission, and the BC Oil and Gas Research and Innovation Society (BC OGRIS) in 2014, to develop a program that would address the challenges of water disposal.
Called the Deep Aquifer Fluid Disposal, or DAFD project, the objective was to characterize the capacity of deep disposal zones within the Montney unconventional play fairway in northeast B.C. Petrel Roberston Consulting Ltd. (PCRL) was contracted to perform the first step of the DAFD project: map and characterize three different deep saline aquifers identified as high-priority disposal zone targets.
A regional map suite was created by PCRL using the region's pre-existing well information in combination with rock samples to examine the ability of the zones to accommodate large volumes of produced water. The maps also give a high/medium/low favourability ranking for each potential aquifer or zone, where high favourability indicates areas with good aquifer characteristics and capacity with little or no risks arising from development of potential nearby shale gas reservoirs. On the other hand, a low favourability ranking for a target aquifer indicates poor aquifer characteristics and/or significant risks of impacts from existing or potential shale gas development.
In early 2015, Geoscience BC engaged Canadian Discovery Ltd. to perform step two of the DAFD project. This will involve a focused assessment of aquifer hydrogeology, including projections of the capacity of the aquifers to accept produced fluids.