This paper presents a method for determining the Archie saturation exponent, n, from a single, nonequilibrium centrifuge step. The input measurements include detailed 3D saturation distributions from magnetic resonance imaging and the DC conductivity of the sample under examination. The latter is obtained by making use of a patented 4-contact cell. The sample is modeled as a 3D conductivity network and a specially developed algorithm based on random walk (RW) is used to compute its overall conductivity in a very short time. The value of the n exponent is determined by matching the measured conductivity to the calculated one. The entire analysis takes one day. Examples demonstrate the method and details of the impedance cell and the RW algorithm are provided.
Use of a New Impedance Cell and 3D MRI to Obtain Fast and Accurate Resistivity Index Measurements from a Single Centrifuge Step
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Bona, N. , Bam, B., Pirrone, M. , and E. Rossi. "Use of a New Impedance Cell and 3D MRI to Obtain Fast and Accurate Resistivity Index Measurements from a Single Centrifuge Step." Petrophysics 53 (2012): 410–419.
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