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.
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Reservoir Characterization—Recent Advances
Optimum reservoir recovery and profitability result from guidance by an effective reservoir management plan. Success in developing the most appropriate reservoir management plan requires knowledge and consideration of (1) the reservoir system, including rocks, fluids, and rock-fluid interactions, as well as wellbores and associated equipment and surface facilities; (2) the technologies available to describe, analyze, and exploit the reservoir; and (3) the business environment under which the plan will be developed and implemented. Reservoir management plans de-optimize with time as technology and the business environment change or as new reservoir information becomes available. Reservoir characterization is the process of creating an interdisciplinary high-resolution geoscience model that incorporates, integrates, and reconciles various types of geological and engineering information from pore to basin scale. The reservoir data are then conceptually and quantitatively modeled and compared to the historical production data and fluid flow distribution patterns within and beyond the limits of the reservoir to match well production histories and predict their behavior. The goals of reservoir characterization are to simultaneously (1) maintain high displacement efficiency, (2) optimize high sweep efficiency, (3) provide reliable reservoir performance predictions, and (4) reduce risk and maximize profits. Notice that in addition to the technical concepts that we normally associate with "characterization," maximizing profits is an essential element of this process. Papers from the Fourth International Reservoir Characterization Technical Conference (1997), sponsored by the U.S. Department of Energy, this publication is a unique compilation of 27 papers covering every aspect of reservoir characterization and has been a popular AAPG publication since that time. Using an interdisciplinary approach, the papers address qualitative information as well as integrated quantified data and culminate in a fully integrated study.