压裂缝网特征对低渗透NAPL污染地层抽提效率的影响机制  

Mechanism of fracture network characteristics on extraction efficiency in lowpermeabilityNAPL-contaminated formations

作　　者：冯世进[1,2] 牛九格 郑奇腾 杨春白雪 FENG Shijin;NIU Jiuge;ZHENG Qiteng;YANG Chunbaixue(State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Geotechnical and Underground Engineering of the Ministry of Education,Tongji University,Shanghai 200092,China;School of Architecture and Civil Engineering,Jinggangshan University,Ji’an 343009,China)

机构地区：[1]同济大学土木工程防灾减灾全国重点实验室,上海200092 [2]同济大学地下建筑与工程系,上海200092 [3]同济大学岩土及地下工程教育部重点实验室,上海200092 [4]井冈山大学建筑与土木工程学院,吉安343009

出　　处：《环境工程学报》2024年第4期1056-1065,共10页Chinese Journal of Environmental Engineering

基　　金：国家重点研发计划资助项目(2020YFC1808104)。

摘　　要：水力压裂可以有效改善低渗透污染地层物质传输速率低的难题,提升修复效率。采用大型多物理场耦合仿真软件COMSOL MULTIPHYSICS模拟低渗污染地层压裂协同抽提修复,分析不同压裂缝网特征对低渗透非水相液体(NAPLs)污染地层抽提效率的影响机制。结果表明,压裂缝网可以有效提升抽提效率,模拟工况的提升率可达42%,且污染物去除率均随着裂隙厚度、长度和渗透率的增加而提高,裂隙渗透率是最主要的影响因素。通过缝网特征参数的耦合分析发现,当裂隙渗透率k_(f)/k大于100时,污染物去除率呈先增加后波动降低的趋势,且当裂隙长度为1.5 m时,去除效果最佳,这是因为当裂隙上层污染物被去除后,裂隙长度的促进作用会大幅衰减。因此,当裂隙设置于污染地层的下部,更有利于污染物的去除。Hydraulic fracturing,which can improve substance transport,offers an effective solution to the challenge of remediating low-permeability contaminated formations.This study employed COMSOL Multiphysics,a large-scale multi-physics coupled simulation software,to simulate hydraulic fracturing-assisted extraction of non-aqueous phase liquids(NAPLs)in low permeability formations.The influence of different fracture network characteristics on the extraction efficiency was analyzed.The results demonstrate that the extraction efficiency can be significantly enhanced by the fracture network,with an improvement rate over 42%and the removal rate of pollutants increases with fracture thickness,length,and permeability,with the fracture permeability being the primary influencing factor.Through coupling analysis of fracture network parameters,it was observed that when the ratio of fracture permeability(k_(f))to matrix permeability(k)exceeds 100,the removal rate of pollutants initially increases,then fluctuates before declining.Additionally,the optimal removal effect was achieved with a fracture length of 1.5 m.This phenomenon can be attributed to the substantial attenuation of the promoting effect of fracture length after the removal of pollutants from the upper layer of the fracture.Hence,locating the fracture network in the lower part of the contaminated formation is more advantageous for pollutant removal.

关 键 词：低渗透 污染地层 压裂缝网 NAPL 抽提 

分 类 号：X523[环境科学与工程—环境工程]