利振彬, 黄天明, 庞忠和, 熊德明, 李义曼, 天娇, 李晓, 马凤山, 郝银磊. 2019: 页岩气开发的地下水环境背景值、监测指标及污染示踪方法研究——以焦石坝区块为例. 工程地质学报, 27(1): 170-177. DOI: 10.13544/j.cnki.jeg.2019-056
    引用本文: 利振彬, 黄天明, 庞忠和, 熊德明, 李义曼, 天娇, 李晓, 马凤山, 郝银磊. 2019: 页岩气开发的地下水环境背景值、监测指标及污染示踪方法研究——以焦石坝区块为例. 工程地质学报, 27(1): 170-177. DOI: 10.13544/j.cnki.jeg.2019-056
    LI Zhenbin, HUANG Tianming, PANG Zhonghe, XIONG Deming, LI Yiman, TIAN Jiao, LI Xiao, MA Fengshan, HAO Yinlei. 2019: STUDY ON GROUNDWATER BASELINE QUALITY, MONITORING INDICATORS AND CONTAMINATION TRACING METHODS RELATED TO SHALE GAS DEVELOPMENT: A CASE STUDY IN THE FULING GASFIELD IN SW CHINA. JOURNAL OF ENGINEERING GEOLOGY, 27(1): 170-177. DOI: 10.13544/j.cnki.jeg.2019-056
    Citation: LI Zhenbin, HUANG Tianming, PANG Zhonghe, XIONG Deming, LI Yiman, TIAN Jiao, LI Xiao, MA Fengshan, HAO Yinlei. 2019: STUDY ON GROUNDWATER BASELINE QUALITY, MONITORING INDICATORS AND CONTAMINATION TRACING METHODS RELATED TO SHALE GAS DEVELOPMENT: A CASE STUDY IN THE FULING GASFIELD IN SW CHINA. JOURNAL OF ENGINEERING GEOLOGY, 27(1): 170-177. DOI: 10.13544/j.cnki.jeg.2019-056

    页岩气开发的地下水环境背景值、监测指标及污染示踪方法研究——以焦石坝区块为例

    STUDY ON GROUNDWATER BASELINE QUALITY, MONITORING INDICATORS AND CONTAMINATION TRACING METHODS RELATED TO SHALE GAS DEVELOPMENT: A CASE STUDY IN THE FULING GASFIELD IN SW CHINA

    • 摘要: 页岩气开采过程中水力压裂及废水回注可能带来的环境问题受到越来越多关注。由于水力压裂开采技术涉及的污染物种类众多,因此建立敏感性监测指标对于识别潜在的地下水污染具有重要意义。本文以中国涪陵页岩气田焦石坝区块为例,首先确定了地下水环境背景值(包括水化学、同位素及溶解气);通过页岩水与浅层地下水的端元对比,确定了地下水环境敏感性监测指标与污染示踪方法。结果显示浅层地下水TDS在146~402 mg·L-1之间,属于HCO3-Ca·Mg型,地下水属于年轻地下水(含3 H、14C接近100 pmC),地下水甲烷含量均小于0.01 mg·L-1,水中溶解气的甲烷(CH4)体积比低于0.006 4%,δ13C-CH4总体小于-50‰,为生物成因甲烷(显著区别于热成因页岩气)。涪陵页岩气田焦石坝区块页岩水TDS约为海水两倍,为大气降水成因,显著区别于北美的(蒸发)海水起源。根据页岩水和浅层地下水水文地球化学特征的差异,建立了确定地下水敏感性监测指标的框架,识别出焦石坝区块地下水敏感性指标(7项)。页岩气开发对地下水潜在的污染主要包括气体污染和溶解固体组分污染。对于气体,建立了甲烷含量及同位素组成的端元,并且应用惰性气体进行了两个端元识别;对于溶解固体组分污染,基于浅层地下水背景值数据,可利用本文给出的敏感性指标进行判别。本项研究对于中国页岩气开发的地下水环境保护具有重要的意义,有助于完善页岩气开发过程中地下水环境监测和潜在污染示踪。

       

      Abstract: Environmental issues caused by hydraulic fracturing and wastewater reinjection during shale gas development have been paid more attention to. Because there are a wide variety of pollutants of the hydraulic fracturing, it is necessary to determine sensitive monitoring indicators for potential pollution tracing. This study takes the Jiaoshiba as an example, and has established the baseline values of groundwater environment(including water chemistry, isotopes and dissolved gas). Shallow groundwater is the typical karst water with TDS between 146 and 402 mg·L-1, belonging to HCO3-Ca·Mg water chemistry type. The groundwater samples are in the range of young groundwater(the contained 3H and 14C close to 100 pmC). The mass concentrations for CH4 of all groundwater samples are less than 0.01 mg·L-1 and the volumetric concentrations in dissolved gas of groundwater are less than 0.006 4%. The δ13C-CH4 values for dissolved methane in groundwater are lower than-50‰, suggesting biogenic origin. The TDS of the shale water in the Jisoshiba shale gas field is about twice that of the seawater, but it shows the genesis of atmospheric origin, which is significantly distinguished from the shale water in North America that originates from the seawater(or evaporated seawater). According to the differences of hydrogeochemical characteristics between shale water and shallow groundwater, the framework for determining sensitive monitoring indicators has been established. In the Jiaoshiba gas field, the sensitive indicators have included 7 items. The potential groundwater contamination processes due to shale gas development are mainly from stray natural gas and dissolved solid constituents. For the contamination of stray gas, end-members have been established by the use of methane and noble gas(3He/4He) to identify gas contamination. The contamination from dissolved constituents can be identified by the determined sensitive indicators based on the baseline values of shallow groundwater. This study may hold great significance for the groundwater protection of shale gas development in China and contribute to the improvement of monitoring groundwater environment and tracing potential contamination during shale gas development.

       

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