Study On Azimuthal Electromagnetic Resistivity Logging While Drilling Inversion Method In Anisotropic Formation

In recent years,logging while drilling plays an increasingly important role on logging field,with the wide production of anisotropic fields,especially,unconventional oilfield and the application of directional wells.The inversion of azimuthal electromagnetic resistivity logging while drilling in resistivity anisotropic formation is mainly studied from this paper.Firstly,the response principle of electromagnetic wave propagation resistivity logging is explained and the basic formula is deduced.Then,the horizontal layered anisotropic medium model is established and the electromagnetic field components in the medium are solved by mode wave decomposition method.And the Fast Hankel transform method is used to achieve efficient numerical simulation.Aiming at the azimuth electromagnetic tool,the formation model is designed specially,and the effect of tool parameters and environmental factors on logging response is analyzed comprehensively.Through various numerical simulation examples,the response law is obtained,which provides guidance for electromagnetic logging signal extraction and resistivity inversion.Finally,from the forward modeling of azimuthal electromagnetic resistivity logging while drilling,the 1-D inversion in anisotropic formation is completed by using the modified damped regularized Gauss-Newton method.A large number of numerical examples show that the inversion method has good iterative convergence effect,which will enhance the excellent precision for future well logging evaluation.