Parameter Inversion Based on Levenberg-Marquardt Algorithm for Layered Formation Using Electromagnetic Wave Resistivity Tool

Electromagnetic wave resistivity tool in logging-while-drilling (LWD) technology can provide real-time conductivity information of the surrounding formation and plays a crucial role in geo-steering, drilling optimization and reservoir evaluation. In this paper, a parameter inversion method based on Levenberg-Marquardt (LM) algorithm is proposed to estimate the conductivity and thickness of the layered-formation model. The finite element method (FEM) was used to solve the forward problem, i.e., to obtain the response of the electromagnetic wave resistivity (EWR) tool and Jacobian matrix. The solution of the forward problem solved by the FEM was compared with the theoretical solution. The influence of the conductivity and thickness on the response of the LWD tool was analyzed. Finally, numerical experiments were carried out to evaluate the accuracy of the proposed method.