Environmental impact of hydraulic fracturing on groundwater by isotope composition and hydrochemistry

Hydraulic fracturing is widely applied for unconventional energy to improve production capacity. But concerns exist about the potential negative impacts of hydraulic fracturing on the environment. Previous researches evaluated the impact of hydraulic fracturing on the environment by water quality monitoring qualitatively. Some numerical models were estimated to study it quantitatively. But there is uncertainty in the acquisition of mechanical parameters of deep rock. This study presents a statistical model for studying the environmental impact of hydraulic fracturing on the groundwater in the region. The contribution ratio of CBM co-produced water is calculated to estimate the containment degree by End Member Mixing Analysis. In order to obtain the end members purely, Vertex Component Analysis and Principal Components Analysis are used to extract the end members. The model is applied to Qinshui Basin, China. It was shown that hydraulic fracturing doesn't damage the aquiclude in the region. But shallow groundwater was polluted by CBM co-produced water in the Shizhuang Block. The mixing path of CBM co-produced water is from the surface to the aquifer.