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
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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HCO_3-Ca·Mg型,地下水属于年轻地下水(含~3H、~(14)C接近100 pm C),地下水甲烷含量均小于0.01 mg·L~(-1),水中溶解气的甲烷(CH_4)体积比低于0.006 4%,δ~(13)C-CH_4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。
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 contained3 H and14 C 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 δ13 C-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(3 He/4 He) 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.
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 contained3 H and14 C 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 δ13 C-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(3 He/4 He) 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.
引文
Bagheri R,Nadri A,Raeisi E,et al.2014.Origin of brine in the Kangan gasfield:isotopicand hydrogeochemical approaches[J].Environmental Earth Sciences,72(4):1055-1072.
Bao X W,Eaton D W.2016.Fault activation by hydraulic fracturing in western Canada[J].Science,354(6318):1406-1409.
Barth-Naftilan E,Sohng J,Saiers J E.2018.Methane in groundwater before,during,and after hydraulic fracturing of the Marcellus Shale[J].Proceedings of the National Academy of Sciences of the United States of America,115:6970-6975.
Birkle P.2016.Geochemical fingerprinting of hydraulic fracturing fluids from Qusaiba Hot Shale and formation water from Paleozoic petroleum systems,Saudi Arabia[J].Geofluids,16:565-584.
Cao C H,Zhang M J,Tang Q Y,et al.2015.Geochemical characteristics and implications of shale gas in Longmaxi Formation,Sichuan Basin,China[J].Natural Gas Geoscience,26(8):1604-1612.
Chapman E C,Capo R C,Stewart B W,et al.2012.Geochemical and strontium isotope characterization of produced waters from Marcellus shale natural gas extraction[J].Environmental Science&Technology,46(6):3545-3553.
Clark I D,Fritz P.1997.Environmental isotopes in hydrogeology[M].Boca Raton:Lewis.
Estrada J M,Bhamidimarri R.2016.A review of the issues and treatment options for wastewater from shale gas extraction by hydraulic fracturing[J].Fuel,182:292-303.
Gregory K B,Vidic R D,Dzombak D A.2011.Water management challenges associated with the production of shale gas by hydraulic fracturing[J].Elements,7:181-186.
Guo X S,Hu D F,Wen Z D,et al.2014.Major factors controlling the accumulation and high productivity in marine shale gas in the Lower Paleozoic of Sichuan Basin and its periphery:A case study of the Wufeng-Longmaxi Formation of Jiaoshiba area[J].Geology in China,41(3):893-901.
Haluszczak L O,Rose A W,Kump L R.2013.Geochemical evaluation of flowback brine from Marcellus gas wells in Pennsylvania,USA[J].Applied Geochemistry,28:55-61.
Harkness J S,Darrah T H,Warner N R,et al.2017.The geochemistry of naturally occurring methane and saline groundwater in an area of unconventional shale gas development[J].Geochimica et Cosmochimica Acta,208:302-334.
Howarth R W,Ingraffea A R,Engelder T.2011.Natural gas,should fracking stop[J]?Nature,477(7364):271-275.
Hu D F,Zhang H R,Ni K,et al.2014.Main controlling factors for gas preservation conditions of marine shales in southeastern margins of the Sichuan Basin[J].Natural Gas Industry,34(6):17-23.
Huang T M,Fan Y F,Long Y,et al.2019.Quantitative calculation for the contribution of acid rain to carbonate weathering[J].Journal of Hydrology,568:360-371.
Huang T M,Pang Z H,Tian J,et al.2017a.Methane content and isotopic composition of shallow groundwater:implications for environmental monitoring related to shale gas exploitation[J].Journal of Radioanalytical and Nuclear Chemistry,312(3):577-585.
Huang T M,Pang Z H,Li J,et al.2017b.Mapping groundwater renewability using age data in the Baiyang alluvial fan,NWChina[J].Hydrogeology Journal,25(3):743-755.
Jackson R B,Vengosh A,Darrah T H,et al.2013.Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction[J].Proceedings of the National Academy of Sciences of the United States of America,110(28):11250-11255.
Kondash A J,Albright E,Vengosh A.2017.Quantity of flowback and produced waters from unconventional oil and gas exploration[J].Science of the Total Environment,574:314-321.
Li H S,Son J H,Carlson K H.2016a.Concurrence of aqueous and gas phase contamination of groundwater in the Wattenberg oil and gas field of northern Colorado[J].Water Research,88:458-466.
Li Y M,Huang T M,Pang Z H,et al.2016b.Geochemical characteristics of shallow groundwater in Jiaoshiba shale gas production area:implications for environmental concerns[J].Water,8(12):552.
Li Y M,Huang T M,Pang Z H,et al.2017.Geochemical processes during hydraulic fracturing:a water-rock interaction experiment and field test study[J].Geosciences Journal,21(5):753-763.
Llewellyn G T,Dorman F,Westland J L,et al.2015.Evaluating a groundwater supply contamination incident attributed to Marcellus Shale gas development[J].Proceedings of the National Academy of Sciences of the United States of America,112(20):6325-6330.
Mantell M E.2011.Produced water reuse and recycling challenges and opportunities across Major Shale Plays[R].EPA Hydraulic Fracturing Study Technical Workshop 4 Water Resources Management:29-30.
Molofsky L,Connor J A,Farhat S K,et al.2011.Methane in Pennsylvania water wells unrelated to Marcellus shale fracturing[J].Oil&Gas Journal,109(19):54-67,93.
Nicot J P,Mickler P,Larson T,et al.2017.Methane Occurrences in Aquifers Overlying the Barnett Shale Play with a Focus on Parker County,Texas[J].Ground Water,55(4):469-481.
Osborn S G,Vengosh A,Warner N R,et al.2011.Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing[J].Proceedings of the National Academy of Sciences of the United States of America,108(37):8172-8176.
Ryan M C,Alessi D,Mahani A B,et al.2015.Subsurface Impacts of Hydraulic Fracturing:Contamination,Seismic Sensitivity,and Groundwater Use and Demand Management[R].Canadian Water Network HF-KI Subsurface Impacts Report.
Vengosh A,Jackson R B,Warner N,et al.2014.A critical review of the risks to water resources from unconventional shale gas development and hydraulic fracturing in the United State[J].Environmental Science&Technology,48(15):8334-8348.
Vengosh A,Kondash A,Harkness J,et al.2017.The geochemistry of hydraulic fracturing fluids[J].Procedia Earth and Planetary Science,17:21-24.
Warner N R,Christie C A,Jackson R B,et al.2013.Impacts of shale gas wastewater disposal on water quality in western Pennsylvania[J].Environmental Science&Technology,47(20):207-220.
Warner N R,Darrah T H,Jackson R B,et al.2014.New tracers identify hydraulic fracturing fluids and accidental releases from oil and gas operations[J].Environmental Science&Technology,48(21):12552-12560.
Wei X F,Guo T L,Liu R B.2016.Geochemical features of shale gas and their genesis in Jiaoshiba block of Fuling Shale Gasfield,Chongqing[J].Natural Gas Geoscience,27(3):539-548.
Wei Y Q,Dong Y H,Li G M.2016.Numerical simulation of the fault impact on fracturing fluid migration[J].Hydrogeology&Engineering Geology,43(1):117-123.
Weingarten M,Ge S M,Godt J W,et al.2015.High-rate injection is associated with the increase in U.S.mid-continent seismicity[J].Science,348(6241):1336-1340.
Xiong D M,Zhang S L,Feng B,et al.2016.Present status analysis of environmental protection in exploration and development of Fuling shale gas[J].Journal of Xi'an Shiyou University(Natural Science Edition),31(6):48-53.
Yu M J,Weinthal E,Patino-Echeverri D,et al.2016.Water availability for shale gas development in Sichuan Basin,China[J].Environmental Science&Technology,50(6):2837-2845.
Zhao H J,Ma F S,Liu G,et al.2016.Influence of different scales of structural planes on propagation mechanism of hydraulic fracturing[J].Journal of Engineering Geology,24(5):992-1007.
Zheng Z X,Zhang H D,Chen Z Y,et al.2017.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[J].Environmental Science&Technology,51(11):5889-5898.
曹春辉,张铭杰,汤庆艳,等.2015.四川盆地志留系龙马溪组页岩气气体地球化学特征及意义[J].天然气地球科学,26(8):1604-1612.
郭旭升,胡东风,文治东,等.2014.四川盆地及周缘下古生界海相页岩气富集高产主控因素---以焦石坝地区五峰组-龙马溪组为例[J].中国地质,41(3):893-901.
胡东风,张汉荣,倪楷,等.2014.四川盆地东南缘海相页岩气保存条件及其主控因素[J].天然气工业,34(6):17-23.
魏祥峰,郭彤楼,刘若冰.2016.涪陵页岩气田焦石坝地区页岩气地球化学特征及成因[J].天然气地球科学,27(3):539-548.
魏亚强,董艳辉,李国敏.2016.断层对压裂液运移影响的数值模拟研究[J].水文地质工程地质,43(1):117-123.
熊德明,张思兰,冯斌,等.2016.涪陵页岩气勘探开发环保现状分析[J].西安石油大学学报(自然科学版),31(6):48-53.
赵海军,马凤山,刘港,等.2016.不同尺度岩体结构面对页岩气储层水力压裂裂缝扩展的影响[J].工程地质学报,24(5):992-1007.
Bao X W,Eaton D W.2016.Fault activation by hydraulic fracturing in western Canada[J].Science,354(6318):1406-1409.
Barth-Naftilan E,Sohng J,Saiers J E.2018.Methane in groundwater before,during,and after hydraulic fracturing of the Marcellus Shale[J].Proceedings of the National Academy of Sciences of the United States of America,115:6970-6975.
Birkle P.2016.Geochemical fingerprinting of hydraulic fracturing fluids from Qusaiba Hot Shale and formation water from Paleozoic petroleum systems,Saudi Arabia[J].Geofluids,16:565-584.
Cao C H,Zhang M J,Tang Q Y,et al.2015.Geochemical characteristics and implications of shale gas in Longmaxi Formation,Sichuan Basin,China[J].Natural Gas Geoscience,26(8):1604-1612.
Chapman E C,Capo R C,Stewart B W,et al.2012.Geochemical and strontium isotope characterization of produced waters from Marcellus shale natural gas extraction[J].Environmental Science&Technology,46(6):3545-3553.
Clark I D,Fritz P.1997.Environmental isotopes in hydrogeology[M].Boca Raton:Lewis.
Estrada J M,Bhamidimarri R.2016.A review of the issues and treatment options for wastewater from shale gas extraction by hydraulic fracturing[J].Fuel,182:292-303.
Gregory K B,Vidic R D,Dzombak D A.2011.Water management challenges associated with the production of shale gas by hydraulic fracturing[J].Elements,7:181-186.
Guo X S,Hu D F,Wen Z D,et al.2014.Major factors controlling the accumulation and high productivity in marine shale gas in the Lower Paleozoic of Sichuan Basin and its periphery:A case study of the Wufeng-Longmaxi Formation of Jiaoshiba area[J].Geology in China,41(3):893-901.
Haluszczak L O,Rose A W,Kump L R.2013.Geochemical evaluation of flowback brine from Marcellus gas wells in Pennsylvania,USA[J].Applied Geochemistry,28:55-61.
Harkness J S,Darrah T H,Warner N R,et al.2017.The geochemistry of naturally occurring methane and saline groundwater in an area of unconventional shale gas development[J].Geochimica et Cosmochimica Acta,208:302-334.
Howarth R W,Ingraffea A R,Engelder T.2011.Natural gas,should fracking stop[J]?Nature,477(7364):271-275.
Hu D F,Zhang H R,Ni K,et al.2014.Main controlling factors for gas preservation conditions of marine shales in southeastern margins of the Sichuan Basin[J].Natural Gas Industry,34(6):17-23.
Huang T M,Fan Y F,Long Y,et al.2019.Quantitative calculation for the contribution of acid rain to carbonate weathering[J].Journal of Hydrology,568:360-371.
Huang T M,Pang Z H,Tian J,et al.2017a.Methane content and isotopic composition of shallow groundwater:implications for environmental monitoring related to shale gas exploitation[J].Journal of Radioanalytical and Nuclear Chemistry,312(3):577-585.
Huang T M,Pang Z H,Li J,et al.2017b.Mapping groundwater renewability using age data in the Baiyang alluvial fan,NWChina[J].Hydrogeology Journal,25(3):743-755.
Jackson R B,Vengosh A,Darrah T H,et al.2013.Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction[J].Proceedings of the National Academy of Sciences of the United States of America,110(28):11250-11255.
Kondash A J,Albright E,Vengosh A.2017.Quantity of flowback and produced waters from unconventional oil and gas exploration[J].Science of the Total Environment,574:314-321.
Li H S,Son J H,Carlson K H.2016a.Concurrence of aqueous and gas phase contamination of groundwater in the Wattenberg oil and gas field of northern Colorado[J].Water Research,88:458-466.
Li Y M,Huang T M,Pang Z H,et al.2016b.Geochemical characteristics of shallow groundwater in Jiaoshiba shale gas production area:implications for environmental concerns[J].Water,8(12):552.
Li Y M,Huang T M,Pang Z H,et al.2017.Geochemical processes during hydraulic fracturing:a water-rock interaction experiment and field test study[J].Geosciences Journal,21(5):753-763.
Llewellyn G T,Dorman F,Westland J L,et al.2015.Evaluating a groundwater supply contamination incident attributed to Marcellus Shale gas development[J].Proceedings of the National Academy of Sciences of the United States of America,112(20):6325-6330.
Mantell M E.2011.Produced water reuse and recycling challenges and opportunities across Major Shale Plays[R].EPA Hydraulic Fracturing Study Technical Workshop 4 Water Resources Management:29-30.
Molofsky L,Connor J A,Farhat S K,et al.2011.Methane in Pennsylvania water wells unrelated to Marcellus shale fracturing[J].Oil&Gas Journal,109(19):54-67,93.
Nicot J P,Mickler P,Larson T,et al.2017.Methane Occurrences in Aquifers Overlying the Barnett Shale Play with a Focus on Parker County,Texas[J].Ground Water,55(4):469-481.
Osborn S G,Vengosh A,Warner N R,et al.2011.Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing[J].Proceedings of the National Academy of Sciences of the United States of America,108(37):8172-8176.
Ryan M C,Alessi D,Mahani A B,et al.2015.Subsurface Impacts of Hydraulic Fracturing:Contamination,Seismic Sensitivity,and Groundwater Use and Demand Management[R].Canadian Water Network HF-KI Subsurface Impacts Report.
Vengosh A,Jackson R B,Warner N,et al.2014.A critical review of the risks to water resources from unconventional shale gas development and hydraulic fracturing in the United State[J].Environmental Science&Technology,48(15):8334-8348.
Vengosh A,Kondash A,Harkness J,et al.2017.The geochemistry of hydraulic fracturing fluids[J].Procedia Earth and Planetary Science,17:21-24.
Warner N R,Christie C A,Jackson R B,et al.2013.Impacts of shale gas wastewater disposal on water quality in western Pennsylvania[J].Environmental Science&Technology,47(20):207-220.
Warner N R,Darrah T H,Jackson R B,et al.2014.New tracers identify hydraulic fracturing fluids and accidental releases from oil and gas operations[J].Environmental Science&Technology,48(21):12552-12560.
Wei X F,Guo T L,Liu R B.2016.Geochemical features of shale gas and their genesis in Jiaoshiba block of Fuling Shale Gasfield,Chongqing[J].Natural Gas Geoscience,27(3):539-548.
Wei Y Q,Dong Y H,Li G M.2016.Numerical simulation of the fault impact on fracturing fluid migration[J].Hydrogeology&Engineering Geology,43(1):117-123.
Weingarten M,Ge S M,Godt J W,et al.2015.High-rate injection is associated with the increase in U.S.mid-continent seismicity[J].Science,348(6241):1336-1340.
Xiong D M,Zhang S L,Feng B,et al.2016.Present status analysis of environmental protection in exploration and development of Fuling shale gas[J].Journal of Xi'an Shiyou University(Natural Science Edition),31(6):48-53.
Yu M J,Weinthal E,Patino-Echeverri D,et al.2016.Water availability for shale gas development in Sichuan Basin,China[J].Environmental Science&Technology,50(6):2837-2845.
Zhao H J,Ma F S,Liu G,et al.2016.Influence of different scales of structural planes on propagation mechanism of hydraulic fracturing[J].Journal of Engineering Geology,24(5):992-1007.
Zheng Z X,Zhang H D,Chen Z Y,et al.2017.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[J].Environmental Science&Technology,51(11):5889-5898.
曹春辉,张铭杰,汤庆艳,等.2015.四川盆地志留系龙马溪组页岩气气体地球化学特征及意义[J].天然气地球科学,26(8):1604-1612.
郭旭升,胡东风,文治东,等.2014.四川盆地及周缘下古生界海相页岩气富集高产主控因素---以焦石坝地区五峰组-龙马溪组为例[J].中国地质,41(3):893-901.
胡东风,张汉荣,倪楷,等.2014.四川盆地东南缘海相页岩气保存条件及其主控因素[J].天然气工业,34(6):17-23.
魏祥峰,郭彤楼,刘若冰.2016.涪陵页岩气田焦石坝地区页岩气地球化学特征及成因[J].天然气地球科学,27(3):539-548.
魏亚强,董艳辉,李国敏.2016.断层对压裂液运移影响的数值模拟研究[J].水文地质工程地质,43(1):117-123.
熊德明,张思兰,冯斌,等.2016.涪陵页岩气勘探开发环保现状分析[J].西安石油大学学报(自然科学版),31(6):48-53.
赵海军,马凤山,刘港,等.2016.不同尺度岩体结构面对页岩气储层水力压裂裂缝扩展的影响[J].工程地质学报,24(5):992-1007.