Spe 68778

SPE 68778 Gas Slippage in Two-Phase Flow and the Effect of Temperature
Kewen Li, SPE, and Roland N. Horne, SPE, Stanford University

This paper was prepared for presentation at the SPE Western Regional Meeting held in Bakersfield, California, 26–30 March 2001. This paper was selected for presentation by an SPE Program Committee following review of information contained in an abstract submittedby the author(s). Contents of the paper, as presented, have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material, as presented, does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Papers presented at SPE meetings are subject to publication review by Editorial Committees of theSociety of Petroleum Engineers. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of where andby whom the paper was presented. Write Librarian, SPE, P.O. Box 833836, Richardson, TX 75083-3836, U.S.A., fax 01-972-952-9435.

Abstract Gas slippage in single-phase gas flow (Klinkenberg Effect) has been investigated extensively. Few papers, however, have been published on the gas slippage in gas-liquid two-phase flow. The gas relative permeabilities at water saturations close to the residualvalue have been found to be significantly greater than one in both nitrogen-water and steam-water flow through rocks. These values became less than one after the calculation was calibrated by taking the two-phase gas slip effect into consideration. The gas relative permeabilities have been measured at different mean pore pressures and the values of two-phase gas slip factor have been computed atdifferent water saturations. The effects of temperature on both nitrogen and steam slip factors have also been studied and compared. These data have then been used to conduct a calibration in order to obtain intrinsic gas relative permeabilities that do not vary with the test pressures. It has been found from the present work that neglecting the two-phase gas slip effect may overestimate gasrelative permeabilities. It is the intrinsic gas relative permeabilities instead of those measured at low test pressure that should be utilized in numerical simulation or other reservoir engineering calculation. Introduction Gas-liquid relative permeabilities are fundamental properties in reservoir engineering and numerical simulation. There may be significant effect of gas slippage in gas-liquidtwo-phase flow. However, few experimental data regarding the gas slip effect in two-phase flow have been published. If the slip effect is not considered correctly, the gas relative permeabilities will vary with test pressures and may be greater than one at some water saturations. On the other hand, little attention has been paid to the measurements of steam slip factor even in single-

phase flow.Reliable data for steam flow is essential to the study of steam injection in heavy oil reservoirs or water injection in geothermal reservoirs where steam is produced. Rose1 conducted experimental measurements of gas relative permeabilities in both synthetic cores (Alundum filters) and natural sandstone cores. Rose1 reported that the gas slip factor of the sandstone cores decreased with the increaseof the liquid (water) saturation. Fulton2 performed experiments on Pyrex cylindrical filters and also found that the gas slip factor decreased with the increase of the liquid (water) saturation in a range from 0 to about 30%. These experiments were not conducted at liquid saturations above 30%. Therefore, Estes and Fulton3 extended their experiments to liquid saturations over 30%, ranging from 0...