Hydraulic fracturing combined with horizontal drilling has revolutionized the oil and gas industry in Western Canada and worldwide. During the process, fracturing fluid, a solution made up of water and chemical additives, is injected into the target hydrocarbon-bearing formation at high pressures, causing the formation to fracture. Following initial fracturing, chemical interactions between the fracturing fluid and the formation which define the chemistry of the wastewater that returns to the surface, commonly referred to as flowback and produced water (FPW). Most of our understanding of the environmental impacts of hydraulic fracturing is limited to analyses of FPW, which often contains potentially toxic heavy metals, polycyclic aromatic hydrocarbons (PAHs) and other hydrocarbon range organic compounds. FPW also commonly have salinity levels exceeding 200,000 ppm. Here, we conduct stirred batch reactor experiments using Duvernay core samples from two wells in the Upper Devonian Duvernay Formation, an organic-rich shale in Alberta that is the focus of oil and gas exploration and development. The samples represent different rock compositions and thermal maturities. Experiments will determine the effects that the salinity of injected fracturing fluid has on the leachability of host rocks during hydraulic fracturing at elevated pressures and temperatures.  This knowledge is not only useful for predicting flowback chemistry, critical to developing effective FPW treatment and reuse strategies, but also reducing the potential damage to the surface environment in the event of a spill.<br/>

Effects of salinity on the leachability of ionic species from the Duvernay formation, a Canadian hydraulic fracturing play

2019 Fall National Meeting

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