Numerical Simulation And Signal Processing Of Azimuthal Electromagnetic Logging While Drilling In Time Domain

With the deepening of deep/ultra-deep oil and gas exploration and development,it is necessary to realize the characterization of the physical properties,structure and fluid properties of deep oil and gas reservoirs,complete the pre-drilling prediction of the cm～ m structure of the reservoir,and meet the needs of accurate geological guidance and fine reservoir evaluation.Time-domain electromagnetic wave logging while drilling uses the rich geological information contained in the time-domain measurement signal,which can break through the spatial evaluation scale of traditional logging technology,and provide pre-drilling and deep formation information and reservoir positioning.It is a key technology for geological steering of complex horizontal wells.This paper focuses on the forward numerical simulation and signal processing of electromagnetic logging while drilling in time domain.Based on the basic theory of transient electromagnetic in time domain,the analytical formula of electromagnetic responses of horizontal stratiform anisotropic formation is derived,and the integral formula of Bessel function is solved by Hankel filter.Combined with the advantages of G-S transform and sine transform,the responses of time domain well logging signal is obtained by hybrid algorithm.The well logging responses under different conditions is simulated,the whole area apparent resistivity algorithm is used to extract the formation resistivity information.The physical law of well logging responses can be well analyzed by using the “smoke ring” theory.Aiming at the azimuthal electromagnetic wave logging instrument while drilling in time domain,the dual-send and dual-receive compensation instrument structure is adopted to solve the problem of non-zero interference of azimuthal geological signal,simulate the response of azimuthal logging instrument under different instrument parameters and formation conditions,and summarize the responses law of azimuthal geological signal in time domain.Finally,discrete time window method and eddy current diffusion theory are used to convert the time-domain logging response into the information of formation electrical parameters and formation depth.The apparent resistivity curves of well logging at different depths and the distance between the instrument and the formation interface are obtained,which improves the comprehensive interpretation and evaluation ability of time domain electromagnetic well logging data.