贵州寒武系和石炭系页岩气开采对环境影响分析——以牛蹄塘组和打屋坝组为例

摘要

Objectives:The shale gas is the important new resources in the global,and its development growing all over the world.Therefore,it is important issue on the destruction of groundwater reservoirs during exploring the process of hydraulic fracturing in extracting shale gas,and the various chemicals used in fracturing fluids might pollute the groundwater.Hence,it's necessary to study this issue,so as to formulate strategies to protect the groundwater.Methods:There are 10.48 trillion cubic meters shale gas in Guizhou Province,according to the national potential assessment of shale gas resources in 2011.The shale gas resources in the Cambrian Niutitang Formation shale and Carboniferous Dawuba Formation shale in Guizhou Province are abundant.We analyze damaging effects of groundwater reservoirs during exploring the process of hydraulic fracturing in extracting shale gas,by studying on strata set,lithological characteristics,geochemistry and reservoir characteristics of Niutitang Formation and Dawuba Formation shales.Additionally,we done shale immersion test by fracturing fluid.Results:Based on the field investigation and lab tests,the main progresses of the thesis are as follows:①The result shows that the mass concentration of the element in fracturing fluid rise with time and temperature,especially significant leaching of elements such as As,Cd,Pb,Se,Co,Ba,which will have enormous effect on environment.②Owing to aquifer and aquifuge destroyed by the extraction of shale gas,the groundwater pollution model was established.③The risk of environmental contamination for flowback fracturing fluid analyzed in the paper.Conclusions:The groundwater pollution model was established,owing to aquifer and aquifuge destroyed by the extraction of shale gas,and the risk of environmental contamination for flowback fracturing fluid analyzed in the paper.%贵州页岩气地质资源量巨大,达到1.048×1013m3.其中寒武系牛蹄塘组与石炭系打屋坝组是重要储集层位.本文在研究牛蹄塘组页岩与打屋坝组页岩的地层结构、岩性和地球化学特征,以及储层特征的基础上,分析水力压裂方法对地下水含水层的破坏作用,建立了页岩气压裂开采导致地下水含水层、隔水层被破坏引起地下水污染模式,预测了压裂液返排地面可能造成地表环境污染的风险.同时,采取牛蹄塘组和打屋坝组页岩进行浸泡试验,试验结果表明,页岩在浸泡过程中,元素的浓度随着时间、温度的变化而变化,并呈现出一定的规律性,特别是As、Cd、Pb、Se、Co、Ba等元素呈显著浸出,据此分析了水力压裂法在开采页岩气的过程中可能会产生的环境污染问题.