Cased Hole Electromagnetic Logging Theory And Parameter Optimization

With the sustained and rapid economic development, the demand for oil is growing, themain oil field have been the high water content of the development phase, and oil outputcapacity gradually decreased. Therefore, it is an important research direction to extend the lifeof existing wells, improve productivity, correctly evaluate reservoir water-flooded degree,determine oil saturation, look for the remaining oil-rich region to ensure stable production ofcrude oil. The transient electromagnetic methods are introduced into the detection field of thecased hole logging system to achieve the detection of residual oil, because the system withmore sensitive to the low resistivity layer and large of detection has the separability in timeand space.Based on the theory of transient electromagnetic methods, the related problems of thecased hole logging system were analyzed; the basic problems of the cased hole logging systemwere discussed. The paper derives the theoretical formula for the borehole electromagneticresponse of four-cylindrical-layer model about borehole, the casing, the cement sheath and theformation. The influencing Factors of transient electromagnetic response are studied bynumerical simulation and put forward the optimization method. In the forward theoreticalbasis, it propose a one-dimensional inversion methods and algorithms, and this method isapplied to inversion of formation resistivity, verify the correctness of the forward model.On the basis of theoretical research, it designs a scheme of the cased hole logging system,and introduces various probe design, transmitting system, receiving system, the relatedhardware circuit design and test content.Through the theoretical and experimental research, The paper proposed the cased welllogging method can achieve the anticipated effect, and provides important reference fortransient electromagnetic detection technology.