Patent ID: 6430509
Filing Date: 2002-08-06
Classification: G01V

Abstract:
A method for 2D inversion of true resistivity from dual laterolog tool measurements, using a pre-calculated look-up table, comprising the steps of:deriving an initial layered earth model; dividing the earth model into intervals; calculating a 2D tool response in each interval from the earth model; checking whether the 2D tool response and the tool measurements substantially match; and iterating the following steps until the match is satisfactory: deriving a 1D radial tool response in each interval using the pre-calculated look-up table; calculating shoulder bed effects in each interval by subtracting the 1D radial tool response from the 2D tool response; and applying a non-linear least square optimization at boundaries of the intervals and local maximum and minimum values in the intervals to update the earth model.