Study On The Interpretation Depth Of Transient Electromagnetic Method

The development of transient electromagnetic method was introduced in this paper. It was analyzed that the reasons of further research interpretation depth and discussed the significance of the depth of interpretation. It was introduced that the principle of transient electromagnetic method and basic principle of the Hankel transformTo solve the Hankel transform coefficients of the code was written by FORTRAN,Using MATLAB compile programof the transient electromagnetic method forward and calculating interpretation depth,3 groups of Hankel transform coefficients were calculated,the accuracy of different filter coefficients and the method of improving the accuracy wereanalyzed.The relationship was studied between depth of interpretation and the lengthof transmitting and receiving coil and the layer parameters of geoelectric model(the thickness of the middle layer and the resistivity).It is found that with the increase of lengthof transmitting and receiving coil will also increase the depth of interpretation,but after reaching a certain value, it has no relation with the size of the wire frame.The smaller the thickness of the middle layer, the signal is smaller, the more difficult to distinguish the signal from the data acquired. The depth of interpretation is smaller,with the thickness of the middle layer becomes larger, the stronger the signal is, there are the greater the depth of interpretation.It was studied that the relationship between Hankel transform coefficient and the Interpretation depth. It was analysis thatthe relationship between the Hankel transform coefficient and the depth of interpretation with example.When the first layer resistivity is 200Ω?m,middle layer resistivity is 40Ω?m,the thickness is 100 m,third layerresistivity is 200Ω?m,the coil length is 100 m,using Hankel transform coefficients of 283 points,interpretation depth reach 1300 m.Theinterpretationdepth reach 2000 m when the filtercoefficient is140 points.