Exploration And Research Of Borehole-ground Electrical Method And High-density Resistivity Method Combined

The borehole-ground electrical method is a exploration way which arrange a certain number of electrodes in the surface by importing the high-power current as the source in the well. The method is an effective technology means to analyze the distribution of the residual oil in high water cut oil field and explore the concealed deposit in depths and margins of crisis mines. In addition, the borehole-ground electrical method has certain production significance in the survey of hydrologic geology and coalfield boundary. The high-density resistivity method is widely used in the search for groundwater investigation, goaf survey, foundation investigation, fault recognition, ect. Its main application areas for the shallow target body. If we combined high-density electrical method and borehole-ground electrical method to detect underground target body, we can get more information about the underground field which contribute to the solution of practical problems in production and has good production practice significance. In this thesis,it mainly focus on the the2.5-D FEM forward of the borehole-ground electrical method and high-density resistivity method and becomes the basis of the inversion imaging.In the paper starting from the boundary value problem of borehole-ground and high-density electrical method, we derived the2.5-D detailed formula and wrote the corresponding program with finite element method. The program calculates the forward results of a horizontally layered ground model and a underground uniform model to verify the correctness and effectiveness of the algorithm.We get the two-dimensional apparent resistivity section map of the borehole-ground electrical method and the high-density electrical method then consider the abnormal response of different target geological body by forwarding the different geoelectric models which is well as the center, the combination of both can better determine the range of the target body; studied the borehole-ground electrical method in the longitudinal direction detection capability,we can get the composite nomaly of the abnormal response. In the paper,these research results have laid a good foundation for further inversion imaging of borehole-ground method and high-density electrical method, also provide basis for field production practices.