Geochemical Characteristics of Shallow Groundwater in Jiaoshiba Shale Gas Production Area: Implications for Environmental Concerns

Abstract

Abstract:The geochemical characteristics of shallow groundwater are essential for environmental impact studies in the shale gas production area. Jiaoshiba in the Sichuan basin is the first commercial-scale shale gas production area in China. This paper studied the geochemical and isotopic characteristics of the shallow groundwater of the area for future environmental concerns. Results show that the average pH of the shallow groundwater is 7.5 and the total dissolved solids (TDS) vary from 150 mg/L to 350 mg/L. The main water types are HCO 3 -Ca and HCO 3 -Ca·Mg due to the carbonates dissolution equilibrium in karst aquifers. The concentrations of major ions and typical toxic elements including Mn, Cr, Cu, Zn, Ba, and Pb are below the drinking water standard of China and are safe for use as drinking water. The high nitrate content is inferred to be caused by agricultural pollution. The shallow groundwater is recharged by local precipitation and flows in the vertical circulation zone. Evidences from low TDS, water isotopes, and high 3 H and 14 C indicate that the circulation rate of shallow groundwater is rapid, and the lateral groundwater has strong renewability. Once groundwater pollution from deep shale gas production occurs, it will be recovered soon by enough precipitation.

Radioactivity of Soil, Rock and Water in a Shale Gas Exploitation Area, SW China

“…Some studies have assessed the baseline level of the methane content, major ions and typical toxic elements of shallow groundwater in the Fuling shale gas area [16]. However, there is no study on the radioactivity levels of different reservoirs.…”

Groundwater resources monitoring during unconventional oil and gas extraction: South African laboratory analytical capabilities

“…Various studies (Montcoudiol et al, 2017;Li et al, 2016;Scholes et al, 2016;Eco Logical Australia, 2012;Mair et al, 2012;Susong et al, 2012) have reported that groundwater resource quality monitoring before, during, and after UOG extraction is important to protect groundwater resources. Limited laboratory analytical capacity may, however, hamper effective monitoring.…”

“…Estimates of shale gas resources in China suggest that its gas deposits dwarf those of the US, with 1 115 trillion cubic feet (Tcf) of technically recoverable shale gas resources compared to 665 Tcf in the US (EIA, 2013). China wants to develop these vast deposits (Downie and Drahos, 2017) and places a high premium on the establishment of a groundwater baseline, as well as longterm monitoring to identify groundwater contamination (Li et al, 2016). Li et al (2016) recommend that baseline groundwater monitoring for UOG production be carried out in China for 5 or 6 years before shale gas production.…”

“…China wants to develop these vast deposits (Downie and Drahos, 2017) and places a high premium on the establishment of a groundwater baseline, as well as longterm monitoring to identify groundwater contamination (Li et al, 2016). Li et al (2016) recommend that baseline groundwater monitoring for UOG production be carried out in China for 5 or 6 years before shale gas production.…”

Baseline Groundwater Quality before Shale Gas Development in Xishui, Southwest China: Analyses of Hydrochemistry and Multiple Environmental Isotopes (2H, 18O, 13C, 87Sr/86Sr, 11B, and Noble Gas Isotopes)

“…Thus, establishing geochemical baseline datasets of shallow groundwater systems before shale gas production is necessary, which can not only provide direct evidence when contamination occurs, but can also reduce controversies of shallow groundwater pollution after hydraulic fracturing [28][29][30]. Currently, a few sites, such as Pennsylvania, USA [31], Colorado, USA [32], Quebec, Canada [33], North Yorkshire, UK [34], and Chongqing, China [35,36], have developed baseline investigation of groundwater before drilling shale gas wells.…”