沁南地区煤层气开发产出水对环境的影响分析

摘要

针对煤层气开发过程中产出水污染物含量较高、容易对开发区域内的环境产生影响的问题,以沁南地区柿庄煤层气开发区块为研究对象,通过分析煤层气产出水对水环境、土壤以及植物的影响,提出相对应的环境污染防治措施和建议.研究结果表明,煤层气产出水普遍呈弱碱性,矿化度较高,其中悬浮物含量、挥发酚以及CODcr指标严重超标;产出水中氟化物以及微量元素铁、锰、铅等均超过Ⅲ级地下水质量标准;产出水排放口的土壤pH值最高达到了10.21,钠吸附比值SAR最高达14.6 mmol1/2/L1/2,是周边农田土壤的8倍多,电导率EC值最高达到4 452 μS/cm,为周边农田土壤的7.2倍.种子萌发率实验结果说明,高矿化度的产出水会抑制农作物的生长发育.针对沁南地区煤层气开发过程中产出水对环境的影响分析结果,提出了通过优选钻完井液和压裂液、优化产出水处理工艺以及加强环保监测等措施,防治煤层气产出水对环境的污染,以期为沁南地区煤层气的合理开发提供借鉴.%In view of the high water content of pollutants produced during the process of CBM development,prone to affect the development of the environment in the region,taking Shizhuang CBM development area in Qinnan as the research object,through the analysis of coalbed methane water on water environment,soil and plant effects,environmental pollution prevention and control measures and suggestions were put forward in the paper.The results show that the output of coal bed methane is generally weak alkaline,and the degree of mineralization is high,and the content of suspended matter,volatile phenol and CODcr index are seriously exceeded;the production of fluoride and trace elements such as iron,manganese and lead in water are over Ⅲ grade groundwater quality standard;the soil pH produced water discharge port the highest value reached 10.21,sodium adsorption ratio SAR up to 14.6 mmol1/2/L1/2,is 8 times more than the surrounding soil,the conductivity of the highest EC value reached 4 452 μS/cm,7.2 times around the farmland soil.The results of seed germination test indicated that the high salinity water could inhibit the growth and development of crops.In view of the influence of output water development process of coalbed gas on the environment of Qinnan area,it was put forward that by optimizing drilling and completion fluid and fracturing fluid,optimization of output water treatment process and strengthen environmental monitoring and other measures,to control coal gas produced water pollution to the environment,in order to provide some reference for the rational development of coalbed methane in southern Qinshui Basin area.