Hydrogeochemical and Isotopic Indicators of Hydraulic Fracturing Flowback Fluids in Shallow Groundwater and Stream Water, derived from Dameigou Shale Gas Extraction in the Northern Qaidam Basin

作者：Zheng, Zhaoxian; Zhang, Hongda; Chen, Zongyu^*; Li, Xufeng; Zhu, Pucheng; Cui, Xiaoshun

来源：Environmental Science & Technology, 2017, 51(11): 5889-5898.

DOI：10.1021/acs.est.6b04269

• GEOCHEMICAL EVIDENCE
• STRONTIUM ISOTOPES
• ROCK INTERACTIONS
• BORON ISOTOPE
• CHINA
• BRINE
• PENNSYLVANIA
• TRACERS
• MARINE
• ORIGIN

Most of the shale gas production in northwest China is from continental shale. Identifying hydrogeochemical and isotopic indicators of toxic hydraulic fracturing flowback fluids (HFFF) has great significance in assessing the safety of drinking water from shallow groundwater and stream water. Hydrogeochemical and isotopic data for HFFF from the Dameigou shale formations (Cl/Br ratio (1.81X10(-4)-6.52X10(-4)), Ba/Sr (>0.2), delta B-11 (-10-1) and epsilon(SW)(Sr) (56-65, where epsilon(SW)(Sr) is the deviation of the Sr-87/Sr-86 ratio from that of seawater in parts per 10(4))) were distinct from data for the background saline shallow groundwater and stream water before fracturing. Mixing models indicated that inorganic elemental signatures (Br/Cl, Ba/Sr) and isotopic fingerprints (delta B-11, epsilon(SW)(Sr)) can be used to distinguish between HFFF and conventional oil-field brine in shallow groundwater and stream water. These diagnostic indicators were applied to identify potential releases of HFFF into shallow groundwater and stream water prior to fracturing and flowback. The monitored time series data for shallow groundwater and stream water exhibit no clear trends along mixing curves towards the HFFF end member, indicating that there is no detectable release occurring at present.

• 出版日期2017-6-6
• 单位中国地质科学院水文地质环境地质研究所; 中国地质大学（北京）