Multiscale Formation Resistivity Imaging

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractConventional interpretation of array resistivity log data is based on inversion. Multidimensional (2D, 3D) log inversion methods commonly use a single formation model (SFM) for the entire interpretation process. The SFM approach has severe limitations when executing either joint or sequential inversions. Here we present a new multidimensional array resistivity data inversion method that utilizes log-resolutiondependent multiscale formation models (MFM). Each of these resistivity models corresponds to a single log or a subset of the multi-array logs. The resistivity model for a particular subset is determined by the expected resolution of the subset logs. Each subset can contain one or more of the multiarray data logs.Our method consists of two main interpretation runs. For the first run, we interpret separate subarray logs using a set of MFMs. For the second, we generate the formation resistivity model or its image by inverting the results from the first in the radial direction. The method is applicable to any array log data acquired in vertical, deviated, or horizontal wells. The test modeling and inversion results are presented.