USE OF A NEW IMPEDANCE CELL AND 3D MRI TO OBTAIN FAST AND ACCURATE RESISTIVITY INDEX MEASUREMENTS FROM A SINGLE CENTRIFUGE STEP

摘要

This paper presents a method for determining the Archie n-exponent 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 that gives access to the entire sample volume and not only part of it.The sample is modelled as a 3D conductivity network and a fit-for-purpose algorithm based on Random Walk (RW) is used to compute its overall conductivity in a very short time.The n-exponent is determined by matching the measured conductivity to the calculated one.The entire analysis takes one day.Examples are presented to demonstrate the method.Details of the impedance cell as well as the RW algorithm are also given.