Theoretical Research On Radial Investigation Depth Of Electromagnetic Induction Logging

Electromagnetic induction logging is an important well logging way. It is used to evaluate the hydrocarbon reserves through detecting the resistivity of the stratum. Low-frequency induction logging is the method of using electromotive force to detecting the resistivity, but high-frequency induction logging is the method of using phase difference rather than electromotive force to detecting the resistivity. At present, there has been a wide range of applications in the oil field exploration and development.During drilling, the borehole mud invasion destroys the original formation and affects the electrical property of the reservoir. Therefore, the hydrocarbon reserves can not be found exactly. In order to detect the resistivity, the radial investigation depth could meet the requirements. In well logging, radial investigation depth is one of the criterions for apparatus application. So the performance of radial direction of the induction logging is discussed in this paper.In this paper, spatial distribution of electromagnetic field is researched with the well that is surrounded by the cylindrical multi-layer media. The electromagnetic field equation is solved with the real axis integration method. After the simulation of the well surrounded by two and three stratums, the borehole and mud invasion affections are analyzed in low-frequency and high-frequency induction logging. At last, radial investigation depth of induction logging is researched, and it is a great help for the induction logging tool design and the design signal correction.Finally, the design of VIKIZ is simply described. Its radical investigation characteristics are analyzed. It is proved that the borehole affection does not exist and the highly radical resolution of the VIKIZ can calculate accurately the resistivity of formation.