混合效应和表皮效应对单井注抽试验的影响机理  

Mechanism of Mixing Effect and Skin Effect on Single-Well Push-Pull Test

作　　者：顾昊琛 凡倩莹 GU Haochen;FAN Qianying(Central South Safety and Environment Technology Research Institute Co.,Ltd.,Wuhan 430051,China;School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430078,China)

机构地区：[1]中南安全环境技术研究院股份有限公司,湖北武汉430051 [2]中国地质大学(武汉)环境学院,湖北武汉430078

出　　处：《安全与环境工程》2023年第2期156-162,共7页Safety and Environmental Engineering

基　　金：中央高校基础研究基金项目(2202010149)。

摘　　要：单井注抽(single-well push-pull,SWPP)试验因为成本低、耗时短和操作简单等优点已经被广泛用于获取含水层中与径向弥散有关的参数。其中混合效应和表皮效应在SWPP试验中起着非常重要的作用,但前人的SWPP试验模型对这两个过程的刻画过于单一。采用有限差分法建立了同时考虑混合效应和表皮效应的SWPP试验模型,通过与前人的SWPP试验模型在特定条件下的对比,验证了模型的合理性,并利用建立的数值模型分析了混合效应和表皮效应对SWPP试验结果的影响机理。结果表明:在SWPP试验中,混合效应和表皮效应对含水层径向弥散的影响不能忽视,当井筒内的地下水体积越大,混合效应越显著,井筒内溶质的穿透曲线较低;当表皮区域弥散度大于含水层弥散度时,表皮厚度越大,越不利于溶质在表皮区域的迁移,而当表皮区域弥散度小于含水层区域弥散度时,表皮厚度越大,越不利于溶质在含水层中的迁移;表皮区域孔隙度越大,对流速度越小,越不利于溶质迁移;参数敏感性分析结果显示,混合效应和表皮效应在SWPP试验中不可忽视。Single well push-pull(SWPP)test has been widely used to obtain parameters related to radial dispersion in aquifer due to its low cost,short time and simple operation.The mixing effect and skin effect have an important role in radial dispersion;however,many previous SWPP models overlook these effects.SWPP model considering both mixing effects and skin effects is developed using the finite difference method,and the rationality of the model is verified by comparing it with the previous SWPP model under specific conditions,the influence mechanism of mixing effect and skin effect on SWPP was analyzed based on the numerical model.The results show that both the mixing effect and skin effect on the radial dispersion of aquifer cannot be ignored in SWPP test,and the larger vol-ume of wellbore results in a lower concentration,As for the case of the dispersion of skin zone is larger than that of aquifer,a greater skin thickness can lead to a slower transport in skin zone,while in the case of the dispersion of skin zone is smaller than that of aquifer,a greater skin thickness can lead to a slower transport in aquifer zone.Fi-nally,the larger the porosities of skin zone,the smaller the velocity in the skin zone is,which leads to a slower transport in skin zone.The results of the parameter sensitivity analysis indicate that the mixing effect and the skin effect are not negligible in the SWPP test.

关 键 词：单井注抽(SWPP)试验 混合效应 表皮效应 有限差分法 

分 类 号：X523[环境科学与工程—环境工程]