Patent ID: 6400148
Filing Date: 2002-06-04
Classification: G01N,G01R,G01V

Abstract:
A method for determining parameters of interest relating to earth formations penetrated by a borehole and error associated therewith, comprising:(a) providing a borehole instrument comprising a plurality of transmitter-receiver pairs, each said transmitter-receiver pair having a transmitter and receiver associated therewith; (b) operating each transmitter of said transmitter-receiver pairs at at least one operating frequency, thereby inducing eddy currents within the formation and the borehole, said eddy currents dependent on the parameters of interest of the formation; (c) measuring voltages in the plurality of receivers responsive to the induced eddy currents thereby obtaining a set of measurements indicative of the parameter of interest; (d) providing a model which relates said set of measurement to the parameters of interest by a set of equations, said equations comprising an overdetermined set; (e) selecting the parameters of interest which are to be determined; (f) obtaining an estimate of said selected parameters of interest by combining the model with a first subset of measurements selected from the set of measurements wherein the number of the selected parameters of interest is less than or equal to the number of measurements in the first subset of measurements; and (g) determining an error associated with said selected parameters of interest by utilizing the estimate of the selected parameters of interest and a second subset of measurements selected from the set of measurements.