高密度电法反演分辨率数值模拟与分析

Numerical simulation and analysis on resolution of inversion of high density electrical method

高密度电法在反演过程中,电极距相比电性异常体横向长度过大时,电性异常体在反演中无法得到约束;某电极距下,当电性异常体埋藏深度增加大到一定深度时,在反演中电性异常体也无法得到约束。针对以上两个问题,利用res2dmod正演软件建立模型,再利用res2dinv反演软件对模型进行反演,通过对比分析结果表明:温纳、偶极和微分三种装置分两种情况:如果电极距小于20m模拟条件下,对于埋藏深度为5m且剖面面积不同的电性异常高阻体(异常体电阻率=100Ω·m,围岩电阻率=10Ω·m),横向反演分辨率,温纳装置大于微分和偶极装置;电极距小于12.75m时,微分装置大于偶极装置,电极距大于12.75m时,偶极装置大于微分装置。如果电极距在2m^8m范围内,对于剖面面积为4×4(m2)的电性异常高阻体(异常体电阻率=100Ω·m,围岩电阻率=10Ω·m),其最大约束深度随电极距的增大而先增大后减小;相同电极距下,偶极装置的最大约束深度>微分装置的最大约束深度>温纳装置的最大约束深度。

In the inversion process,when the electrode distance is too large,the electrical abnormal body cannot be restrained in the inversion.Certain electrode spacing,the electrical anomaly cannot be reversed when the buried depth of the anomalous body increases to a certain depth.In view of the above two problems,using Res2dmod forward software to build the model,reusing the Res2dinv inversion software to invert the model,and obtaining the following conclusions:for wenner-αwenner-βand wenner-γthree kinds of devices.1)The electrode spacing is less than 20m,the resistivity of the resistivity of the buried depth is 5m and the geological scale is different(The resistivity of the anomalous body=100Ω·m,and the resistivity of the buried environment=10Ω·m).the inversion resolution of the winner-αdevice is greater than that of the wenner-βdevice and wenner-γdevice;When the electrode spacing is less than 12.75 m,The inversion resolution of the winner-βdevice is greater than that of the wenner-γdevice;When the electrode spacing is greater than 12.75 m.The inversion resolution of the wenner-γdevice is greater than that of the winner-βdevice.When the electrode spacing is more than 5 times longer than the transverse side of the electrical abnormal body,electrical abnormalities cannot be reversed.2)The electrode is within 2~8 m range,the electrical characteristics of the section area of 4 x 4(m 2)are highly resistive(The resistivity of the anomalous body=100Ω·m,and the resistivity of the buried environment=10Ω·m).The maximum restraint depth increases with the increase of electrode distance and then decreases;under the same electrodes,The maximum restraint depth of wenner-βdevice>the maximum restraint depth of wenner-γdevice>the maximum restraint depth of wenner-αdevice.