Simulation And Application Of Array Laterolog In Anisotropic Formations

In the exploration of high and steep structures at the edge of the basin,the responses of resistivity logs are complex due to the resistivity anisotropic effects and mud invasion,which reduces the accruacty of the formation interpretation.Among resistivity logging methods,the array laterolog can provide abundant information of formation resistivity and mud invasion,therefore can be implemented to evaluate the resistivity anisotropy.In this dissertation,the numerical simulation and physical simulation system are used to study the array laterolog response in anisotropic formation,further more,an array laterolog inversion algorithm based on the anisotropic formation with invasion effects is established to provide a theoretical basis for the accurate evaluation for the anisotropic formations.In the third chapter,a three-dimensional numerical simulation method for array laterolog is developed and applied to the effects analysis of the deviation,mud invasion and anisotropy on the array laterolog.Numerical results show that the array laterolog logging is more sensitive to the mud invasion than the electrical anisotropy.In the fourth chapter,a flexible physical simulation method for array laterolog logging of anisotropic formation is introduced.A scaled down tool of HRLA from Schlumber is developed for the physical simulation in the laboratory.The anisotropic formation with different dip angles is modeled by the interbedded material with different conductivities in a water-filled tank.Specifically,the half-space measurement method is applied to simplify the experiments.The simulation system established in our work is convient to change the formation resistivity and the relative dip angles of the formation.The experimental results agree well with the numerical simulations,which verifies the 3D numerical algorithm for the array laterolog modeling.In the fifth chapter,a graded inversion method for array laterolog logging of anisotropic formation is developed.In the inversion process,the initial model of the array laterolog logging inversion is selected by establishing the database and linear interpolation.The invasion profiles in complex scenarios can then be reconstructed fast by combining with the gradient inversion algorithm.The accuracy of the algorithm is verified by applying to analyze the field logging data,which provides the theoretical basis for the accurate evaluation of the anisotropic formation in complex well conditions.