Research On Interwell Electromagnetic Imaging Method Based On Axisymmetric Two-Dimensional Model

The horizontal detection range of the conventional induction logging is within 10 m of the well,while the lateral detection range of the interwell electromagnetic logging is between two adjacent 100~1000m wells,and there is no mature electromagnetic logging method between the lateral detection range of 10~100m.In this paper,based on the theory of interwell electromagnetic logging,by using the interwell launch and receiving device in a single well,the horizontal detection range of a single well is a numerical simulation of the single well remote detection between 10~100m.The simulation uses the axisymmetric two-dimensional model and uses the BCGS algorithm of the integral equation to simulate the response of the single well far detection and uses the Born iteration to reverse the inversion imaging and studies the influence of the coil distance and the launching frequency on the single well remote detection.The simulation results of the twodimensional anomaly body model at the distance from the well hole 20 m show that when the distance between the coil distance is relatively small and the distance from the abnormal body distance is relatively small,the scattered signal in the received signal is relatively small,and the proportion of the scattered signal in the received signal increases gradually when the coil distance is gradually increased,but the total signal intensity is gradually reduced.When the distance from the distance of the line is close to the distance from the anomalous hole,the scattered signal in the received signal is relatively high,and the signal obtained by a certain emission frequency can be retrieved.The simulation results of the two-dimensional anomalous body model at 40 m from the borehole show that the ratio of the scattered signal is too small for the inversion imaging.On this basis,this paper analyses the results of the single well remote detection test of the post village 4#.By comparing with the well field curve,it shows that the measurement results of the resistivity curve are in agreement with the reality.For threedimensional single well detection,this paper only simulated the abnormal body in the 20 m of the well hole.The results show that it is difficult to detect the scattering signal because of the small size of the abnormal body,so the inversion imaging cannot be carried out.To sum up,in order to detect the existence of electrical conductivity abnormal body,the appropriate frequency and coil distance should be selected according to the distance between the abnormal body and the well hole,and the intensity of the scattering signal is further improved by improving the transmitting intensity and the receiving intensity of the coil.In addition,in order to improve the application of the interwell electromagnetic imaging in the field of engineering,this paper,based on the Fortran program of one dimensional,two-dimensional and three-dimensional electromagnetic positive and negative interactions,adapted the Visual C++ program into a visual graphical interface program to improve the problem of the human computer interaction in the Fortran program.