Research On Error Correction Technology Of Transient Electromagnetic Array

In recent years,transient electromagnetic detection techniques have been widely used in oil and gas engineering fields such as nondestructive testing of downhole casings,production well reservoir monitoring,relief well electromagnetic detection and cluster well anti-collision detection,owning to their time-domain diffusion characteristics of transient pulse response.Based on the transient electromagnetic detection method,this paper focuses on the error correction technology of the borehole transient electromagnetic array using the array signal processing and empirical mode decomposition(EMD),.Firstly,this paper introduces basic principle of TEM array detection,analyzes the influence of well temperature change on the initial permeability and saturation magnetic induction strength of the core,and studies the baseline drift of TEM detection signal.In addition,the background magnetic noise model of transient electromagnetic signal under the dynamic measurement model is established,and the influence of moving speed on the system noise in the dynamic measurement process is studied.In order to solve the above problems,a baseline drift correction and background magnetic noise suppression method based on EMD and set EMD is proposed,and the noise suppression method combining set EMD and wavelet threshold is studied.On this basis,using the correlation between the weighting method of TEM array and the late signal,a noise suppression method of TEM array based on the array set EMD is also proposed,which can effectively reduce the complexity of the set EMD method.At last,indoor and field experiments are carried out to detect the casing damage with TEM array.The experimental results show that the array integrated EMD method proposed in this paper can effectively eliminate and suppress the baseline drift and dynamic measurement noise of the underground TEM array,and improve the performance of the underground detection system effectively.