Research On Signal Processing Of Electromagnetic Wave Logging While Drilling In Anisotropic Formation

Under the background of continuous progress and deepening development of oil and gas exploration worldwide,the application of directional wells(especially highly deviated wells and horizontal wells)is increasing,and electromagnetic logging while drilling has become the key technology to formation evaluation,geosteering and reservoir mapping.However,the resistivity conversion method of conventional electromagnetic wave logging w hile drilling is proposed based on isotropic medium,and its application in anisotropic formation is limited.The signals processing method of electromagnetic wave logging while drilling in electrically anisotropic formation is mainly studied in this thesis.The principle of electromagnetic wave logging w hile drilling is described in detail and the anisotropic formation response formula is deduced,and the 1-D electromagnetic wave logging w hile drilling forward modeling is realized by the fast Hankel transfor m algorithm,a variety of formation models are designed to summarize the influence law of tool parameters and environmental factors on logging response.Then,based on the accurate forward numerical simulation results,the anisotropic formation model is established,and the joint signals solving method is used to extract the anisotropic resistivity parameters,the influence of tool parameters and environmental factors on the method is analyzed,and extended methods for obtaining the same kind of signals with variable frequency or variable source distance is proposed to get the formation anisotropy parameters.Finally,based on forward modeling,the damped regularized Gauss-Newton method is used to complete 1-D inversion of electromagnetic wave logging w hile drilling in anisotropic formation,and a variety of anisotropic formation models are established to analyze and compare the above methods,and verify the effect and accuracy of the inversion method.The results show that the influence of environmental factors on the logging response should be considered in the forward modeling of electromagnetic wave logging w hile drilling;when the target layer is thick,the joint signals solving method can more accurately describe the electrical anisotropy of the formation;the formation resistivity parameters obtained by the inversion research have high accuracy and good applicability to different formation models.It can provide new ideas for formation evaluation,geosteering and reservoir mapping by the comprehensive research in this thesis.