Study On The Transient Electromagnetic Interpretation Method Based On The Inversion Model Of Seismic Wave Impedance

The seismic wave impedance inversion has good effect on the positioning of structure and the layering of rock,which reflects the density information of rock but for the formation of electrical reaction is weak;TEM reflects the electrical information of rock and ore,especially for low resistance response.But TEM exists diverse solutions for the division of strata and the positioning of abnormal body due to the volume effect.This paper proposes a TEM interpretation exploration method combined with the advantages of the exploration of seismic and TEM,which based on the results of seismic wave impedance inversion.The method uses the result of seismic wave impedance inversion and resistivity logging data to build earth-electricity model.At the special and layer position,the resistivity has deviation with actual layer and structure.Doing TEM forward modeling for earth-electricity model.The electrical differences can be obtained by using the data of measured TEM to minus the data of forward.Firstly,the article analyze the feasibility of joint explain.Put the transient electromagnetic response of uniform half space and half space which include high or low resistance abnormal together,then make the difference.As the following results: The early response data smaller than homogeneous half space when the half space include low resistivity abnormal,the late response data is opposite;The early response data larger than homogeneous half space when the half space include high resistivity abnormal,the late response data is opposite.There are positive and negative peak in the curve of the difference of induction electric potential which is obtained by use the response of contain abnormal minus the response of background.The negative peak appears before the positive peak when containing low resistivity anomaly and the peaks appear order is opposite when containing high resistivity anomaly.As the parameter change of the abnormal body resistivity,there are different changes for peaks.For low resistivity anomaly,there are greater peaks when the resistivity is smaller and the change is bigger.For high resistivity anomaly,there are greater peaks when the resistivity is larger and the change is smaller.With the resistivity change,positive and negative peaks position unchanged.The difference of the induction electromotive force curve peaks decrease with the increase of depth.While,the positive and negative peaks position will be delay with increase of depth.As the volume of abnormal body,the positive and negative peak becomes large and the variation amplitude is greater than that caused by the resistivity and depth change.Then,through the integrated interpretation of two typical model to study the change rule of the difference of induction electric potential and apparent resistivity.There are positive and negative peaks appear on the multiple instrument channels profile of difference of induction electric potential and two low resistance response appear on the difference of resistivity profile when the model contains the low resistivity abnormal.Compared with the original data,the integrated interpretation show the abnormal is more apparent.Finally,combined with measured data to verified the feasibility of integrated interpretation method and the profile of the difference of apparent resistivity show obvious that the location and moisture feature of fault.Compared with the single geophysical interpretation,the comprehensive explanation method has higher resolution ability to verify the construct and water.