Numerical Simulation Of Azimuthal Electromagnetic Wave Logging While Drilling

With the rapid development of the world economy and the industry,the increasing demand for the resources of oil and gas,the exploration and development of the Oil and gas fields especially offshore oil and gas fields,the logging while drilling technology attracts more and more attention.The big company overseas launched new type of Directional Electromagnetic LWD Tool one after another,but then in China,the directional Electromagnetic LWD technology is still at an initial stage,without comparatively mature method.In this paper,based on the calculation method of electromagnetic field with FDTD,electromagnetic theory,and the electromagnetic LWD theory,the simulation of the response of Directional Electromagnetic LWD is implemented in one dimensional isotropic formation and three dimensional isotropic formation.Based on the traditional electromagnetic LWD theory and the Directional Electromagnetic LWD theory,the analytical solution of the original magnetic dipole is established in one dimensional isotropic formation.The fast calculation of the integral of Bessel function with the Gauss numerical integration algorithm,the improved asymptotic method and the zero point approach.It is proved that the zero point approach is superior to the Gauss numerical integration algorithm and the improved asymptotic method in calculating precision and speed.As for the improved asymptotic method,the parameter r is bigger(Far greater than 1,such as 1000),the calculation accuracy is higher.Considering the fact of this paper,the simulation of the response of Directional Electromagnetic LWD in one dimensional isotropic formation is implemented quickly based on the zero point approach.Research on the FDTD method in cylindrical coordinates is based on the Maxwell equations,and the problem of the numerical value stability condition,numerical dispersion,absorbing boundary condition,source excitation and so on is discoursed,systematically.Thereby,three dimensional simulation of electromagnetic LWD response in isotropic formation conditions is realized.