碳酸盐岩石裂隙中DNAPL污染物迁移过程的电阻率成像  

Electrical resistivity tomography of DNAPL contaminant migration process in carbonate rock fractures

作　　者：李奔 刘汉乐[1,2] 李培华 程锡治 王清 黄仕龙 刘新宇 金明哲 LI Ben;LIU HanLe;LI PeiHua;CHENG XiZhi;WANG Qing;HUANG ShiLong;LIU XinYu;JIN MinZhe(Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology,Guilin University of Technology,Guilin 541004,China;Collaborative Innovation Center for Water Pollution Control and Water Safety in Karst Area,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]桂林理工大学,广西环境污染控制理论与技术重点实验室,桂林541004 [2]桂林理工大学,岩溶地区水污染控制与用水安全保障协同创新中心,桂林541004

出　　处：《地球物理学进展》2023年第6期2704-2713,共10页Progress in Geophysics

基　　金：国家自然科学基金(42277192);广西自然科学基金(2017GXNSFAA198233);第三期广西高等学校千名中青年骨干教师培育计划联合资助。

摘　　要：重非水相液体(DNAPL)是污染地下水环境的主要污染物之一,为研究DNAPL污染物在裂隙岩石介质中的迁移特征,本试验选用有“人”字形裂隙的碳酸盐岩石为样品,利用电阻率成像法(ERT)监测岩石裂隙介质中DNAPL迁移过程.结果表明:(1)ERT对裂隙中的液体表现出很高的敏感性,在裂隙注满NaCl溶液时,岩石中部电阻率降低到2000Ω·m,表明碳酸盐岩石样品可用于ERT对岩石裂隙中流体迁移的动态监测;(2)DNAPL会首先沿优势通道驱替水流,岩石相对电阻率随时间的动态分布与DNAPL在裂隙中的移动位置具有较好的一致性.说明ERT可以动态监测碳酸盐岩石交叉裂隙中DNAPL的迁移;(3)裂隙中有DNAPL残留并影响电阻率值降低幅度,各测点的电阻率降低幅度与DNAPL在裂隙中的位置密切相关,各测点的电阻率在DNAPL离开测点时下降最为明显.说明裂隙区域电阻率值的变化与DNAPL的迁移及分布相关.本试验证明了ERT监测碳酸盐岩中DNAPL运移的方法是有效的,但是ERT监测复杂裂隙内DNAPL分布的精度仍需进一步提高.In order to study the migration characteristics of Dense NonAqueous Phase Liquid(DNAPL)which is one of the main pollutants that pollute the groundwater environment pollutants in fractured rock media,carbonate rock with cross fractures was selected as samples in this experiment and Electrical Resistivity Tomography(ERT)was used to monitor the migration process of DNAPL in rock fractures.The data collected in realtime by a highdensity electrical instrument were converted into twodimensional resistivity images of DNAPL migration process in these rock fractures,and the migration and distribution characteristics of DNAPL were analyzed by resistivity images.The results showed that:(1)During the injection of NaCl solution,when the solution migrated along fractures,ERT showed high sensitivity to the liquid.When the fractures were filled with NaCl solution,the resistivity in the middle of the rock was reduced to 2000Ω·m,indicating that the carbonate rock sample can be used for ERT dynamic monitoring of fluid migration in rock fractures;(2)During the injection of DNAPL,DNAPL first displaced water flow along the dominant channel,and the dynamic distribution of relative resistivity of rock with time had good agreement with the moving position of DNAPL in fractures.It showed that ERT can dynamically monitor the migration of DNAPL in carbonate rock with crossfractures;(3)During the discharge of DNAPL,DNAPL remained in fractures and affected the resistivity reduction.the resistivity reduction of each measuring point was closely related to the position of DNAPL in fractures and the resistivity of each measuring point decreased most obviously when DNAPL left the measuring point.It showed that the change of resistivity value in the area of the fracture was related to the migration and distribution of DNAPL.This experiment proved that the method of ERT monitoring DNAPL migration in carbonate rocks is effective,but the accuracy of ERT monitoring DNAPL distribution in complex fractures still needs to be further improved.

关 键 词：岩石裂隙 重非水相液体 电阻率成像法 两相流 

分 类 号：P631[天文地球—地质矿产勘探]