Drainage Capillary Pressure and Resistivity Index from Short-Wait Porous-Plate Experiments

Reliable experimental capillary pressure and electrical properties as functions of saturation history are essential as inputs for static and dynamic modeling of a reservoir. The only technique that simultaneously gives both Pc and Sw-RI relationship as functions of saturation history, and does not rely on a model with underlying assumptions for calculation, is the standard equilibrium method. This is also known as the standard porous plate equilibrium method. The only disadvantage with this method is that it is time consuming caused by the low flux through the diaphragm (porous plate). In this paper we present drainage capillary pressure curves and resistivity index measured on reservoir rock samples by the standard equilibrium method at pseudo reservoir conditions. In parallel with this, a sister plug set has been analyzed by interrupting intermediate capillary displacement pressures before reaching equilibrium, with the objective of establishing Sw-RI relationship much faster. The results show that it is possible to establish identical Sw-RI relationship with a time-saving factor of three for the carbonate rock type under study. Saturation data could be fitted to an exponential decay model using nonlinear regression in order to derive accurate capillary pressure curves from short-wait porous plate measurements. In addition, the experimental results were supported by simulation with Sendra. This gave more confidence in the data and opened the way into more future investigations towards examining factors and optimized design of the interrupted capillary displacement pressure tests. INTRODUCTION The most reliable method that can simultaneously measure capillary pressure (Pc) and resistivity index (RI) as a function of water saturation is the standard equilibrium (Eqm) method known as the porous plate (PP). However, this method is quite time consuming, and that is why several methods like the membrane technique [1] and the continuous injection method [2] have been developed to speed up the establishment of these properties. Although these proposed methods can acquire data in a much faster time they