Impacts of Shale Gas Development on Shallow Groundwater—A Case Study from a Shale Gas Production Platform in the Weiyuan Block, Sichuan Basin, China

Shale gas development has raised public concerns about regional groundwater quality. This study investigates the correlation between groundwater geochemical composition and shale gas extraction through a case study of a production platform in the Weiyuan Block, Sichuan Basin. Major ions, trace elements,87Sr/86Sr and δ7Li of shallow groundwater from monitoring wells and domestic wells upstream and downstream of the platform were analysed to identify the origin of different groundwater types. Hydrochemical characteristics show that domestic well samples are controlled by coupled carbonate dissolution and silicate weathering, while monitoring wells exhibit stronger silicate and evaporite dissolution signals. Isotopic data indicate that Sr is derived from mixed carbonate-silicate sources, whereas Li is derived from silicate weathering. In addition, the combination of the major ions, Sr and Li isotopes, can effectively identify the different sources of contamination. Conservative mixing models demonstrate no brine influence in the study area. This study provides a methodological support for monitoring groundwater quality as well as tracing contaminants in shale gas-producing areas.