Method for 2D inversion of dual laterolog measurements

摘要

A 2D inversion of true formation resistivity from dual laterolog tool measurements is accomplished using a pre-calculated look-up table. An initial earth model is derived and divided into intervals. A 2D tool response is calculated in each interval using the earth model. Matching is checked between the calculated 2D tool response and the tool measurements. The following steps are iterated until the match is satisfactory. A 1D radial tool response is derived in each interval using the pre-calculated look-up table. Shoulder bed effects are approximated in each interval by subtracting the 1D radial tool response from the 2D tool response. A non-linear least square optimization is applied at boundaries of the intervals and local maximum and minimum values in the intervals to update the earth model.