A Direct Method for Determining Complete Positive and Negative Capillary Pressure Curves for Reservoir Rock Using the Centrifuge
E. A. Spinier, B. A. Baldwin, 1999. "A Direct Method for Determining Complete Positive and Negative Capillary Pressure Curves for Reservoir Rock Using the Centrifuge", Reservoir Characterization—Recent Advances, Richard A. Schatzinger, John F. Jordan
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A method is developed for direct experimental determination of capillary pressure curves from saturation distributions produced while centrifuging fluids in a rock plug. A free-water level is positioned along the length of the plugs to enable simultaneous determination of both positive and negative capillary pressures. Octadecane, as the oil phase, is solidified by temperature reduction while centrifuging to prevent fluid redistribution upon removal from the centrifuge. The water saturation is then measured via magnetic res-onance imaging. The saturation profile within the plug and the calculation of pressures for each point of the saturation profile allow for a complete capil-lary pressure curve to be determined from one experiment. Centrifuging under oil with a free-water level into a 100% water saturated plug results in the development of a primary drainage capillary pressure curve. Centrifuging similarly at initial water saturation in the plug results in the development of an imbibition capillary pressure curve. Examples of these measurements are presented for Berea sandstone and chalk rocks.