METHOD FOR ITERATIVE DETERMINATION OF CONDUCTIVITY IN ANISOTROPIC DIPPING FORMATIONS

摘要

A method is disclosed for the determination of horizontal resistivity, vertical resistivity, dip and strike angles of anisotropic earth formations surrounding a wellbore . Electromagnetic couplings among a plural of triad transmitters and triad receivers are measured. Each triad transmitter/receiver consists of coil windings in three mutually orthogonal axes. These measured signals are used to generate initial estimates of the dip angle and strike angle of the formation as well as the anisotropy coefficient and the horizontal resistivi ty of the formation. An iterative algorithm is then applied using these quantities to finally arrive at more accurate estimates that approach the true values in the formation.