Responses Simulation of the electromagnetic Logging While Drilling tool in the fractured formation of horizontal well

Low-frequency electromagnetic (EM) Logging While Drilling (LWD) has a deep detection depth, which can identify large-scale fractures and evaluate geometric parameters. In this paper, a rapid forward of EM LWD tool in fractured formations is realized by equivaling the fracture as a transition boundary conditions (TBC). A three-dimensional finite element method (FEM) was used to optimize the space and frequency of the tool, and the effects of fracture aperture and fracture elongation on the response characteristics of logging were analyzed. The results show that the equivalent fracture model has high accuracy and fast calculation speed. Electromagnetic wave logging in fractured formations, the response characteristics vary with the changes of fractures in different spatial positions, and the closer the fracture is to the tool, the more obvious is the response characteristics. And the larger space of the tool, the better fracture detection ability. The response characteristics change more obvious with the increasing the fracture aperture The tool can detect fractures with an elongation greater than the space of the tool. When the elongation is less than the tool space, “multi-resolution” occurs. The fast forward simulation results have good reference value for identifying position information of fracture beside well and EM LWD response.