鄂尔多斯气田泥浆池防渗层对有害物质的阻滞作用评价

随着天然气勘探开发速度的加快,鄂尔多斯气田井场废泥浆产生量越来越大,固化处理后将其填埋于有防渗层的泥浆池中是目前该区域最常用的方法,但国内外就气田井场泥浆池防渗层对池内污染物实际阻滞效果的研究报道较少。为研究上述处理方法的实际环境效应,以2010年盆地内正在开发气井井场泥浆池内预固化处理沉淀物的分析结果为参照,选择其中污染程度较为严重的石油类、COD、硫化物和砷、钡、镍、铅、铜4种为重点污染物,选择2005—2009年分别投入使用的5个气田井场废弃泥浆池为考察对象,分析研究了防渗层投运时间对不同污染物阻滞作用的影响。结果表明,投运1年的防渗层可阻留污染物90%以上,投运2年以上的防渗层对污染物的阻滞作用有不同程度下降,投运5年的防渗层对所监测污染物的阻滞作用最好的是钡(40.14%)、最差的为硫化物(10.89%),结合不同时间防渗层破损状况和其对污染物的阻滞效率的变化情况,说明机械刺穿和不均匀降是导致防渗层在研究区域的环境下阻滞功能退化较快的主要原因。

Evaluation on the pollutants blocking effect of impervious barriers of slurry ponds in Ordos gas field

With an acceleration in the rate of gas exploration and development in Ordos Basin,more and more waste drilling mud has been discharged.One of the most common methods is to bury the mud into the slurry pond equipped with impervious barriers after solidification process.However,few investigations about the pollutants blocking effect of impervious barriers in sites have been reported.In order to reveal the practical environmental effect of the above mentioned method,based on analytic results of pre-solidified deposit from slurry pond that opened in 2010,the pollutants including oil,organism,sulfide,arsenic,nickel,lead,copper and barium were selected as key pollutants,and five slurry ponds put into use in succession during 2005 and 2009 were chosen as investigative targets.Then,the influence of service time of impervious barriers on the pollutants blocking efficiency was studied.The analysis exposed that impervious barrier used for one year could block over 90% of all monitored pollutants,the blocking efficiency of impervious barriers used after two years decreased to different extent,and after 5 years,the blocking effect on barium was the best and that on sulfide was the worst,with 40.14% and 10.89% blocking efficiency,respectively.According to the relationship between the damaged conditions of the impervious barriers and the changes of blocking efficiency at different times,it comes to conclusion that the breakage of high density polyethylene membrane caused by the mechanical penetrating and differential settlement is the main reason that leads to the degradation of blocking effect of impervious barrier.