Geochemical Characteristics and Environmental Significance of Trace Elements in Co-produced Water of Coalbed Methane in Qinshui Basin
In the process of energy structure adjustment,as an unconventional natural gas resources,the development and utilization of coalbed methane(CBM)has gradually attracted attention,since CBM is an important unconventional natural gas resources.The large amount of water produced by the exploitation of coalbed methane has therefore raised concerns about water pollution and other related environmental issues.Qinshui Basin is an important area for the development of CBM in China.This study analyzed samples from 6 blocks in the Qinshui Basin to trace the source and evolution of trace elements in CBM co-produced water,and provided geochemical data support for the follow-up treatments.The main trace element compositions of the water samples in Qinshui Basin include Li,B,F,Mn,Fe,Sr,and Ba.Particularly,F and Mn levels exceed the Chinese drinking water health standards by 7 times and 1.4 times,respectively,corresponding to groundwater quality standards of Class Ⅴ and Class Ⅲ-Ⅳ.The long-term accumulation of elements due to CBM exploitation poses a serious threat to the surrounding environment and human health.Magmatic activities bring a large amount of F to the coal seam in Qinshui Basin.The local water environment,riched in HCO3-,promotes the dissolution of fluoride-containing minerals.The situation of Mn exceeding the standard was the most serious in Yushe and Zhengzhuang.The dissolution of manganese siderite is the main control factor for high concentration of dissolved Mn in coal seam water,and with the increase of buried depth of coal seams and the decrease of pH value,Mn is gradually enriched in CBM co-produced water.The phenomenon of F and Mn exceeding the standard exists widely in coal seam water in China.It is necessary to take appropriate treatment measures for F and Mn before discharging CBM co-produced water.
Qinshui Basincoalbed methane co-produced waterwater qualitytrace elements
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万方数据
