Gas Slippage in Two-Phase Flow and the Effect of Temperature

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractGas 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 residual value 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 at different 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 gas relative 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.

Experimental Verification of Methods to Calculate Relative Permeability Using Capillary Pressure Data

“…Note that the steam relative permeability data shown in Fig. 1 have been calibrated under the consideration of gas slip effect (Klinkenberg Effect 17 ) in twophase flow by Li and Horne 18 .…”

“…These data were also measured simultaneously in the same Berea core sample at a temperature of about 120 o C. The steam relative permeability data shown in Fig. 3 have also been calibrated under the consideration of gas slip effect in twophase flow 18 .…”

“…Li and Horne 18 measured the nitrogen-water relative permeabilities in a fired Berea core sample similar to that used in the measurement of steam-water relative permeabilities by Mahiya 16 . In this study, we drilled a plug from another part of the same fired Berea sandstone that was used by Li and Horne 18 . The length and diameter of the plug sample were 5.029 cm and 2.559 cm respectively; the porosity was 24.37%.…”

“…The drainage nitrogen-water capillary pressure of the plug was measured by using the semipermeable porous-plate method. The measured data of the drainage nitrogen-water capillary pressure along with the relative permeabilities from Li and Horne 18 are plotted in Fig. 5.…”

A General Scaling Method for Spontaneous Imbibition

“…Note that we showed previously that the values of capillary pressure at S wf extracted from the experimental data of spontaneous water imbibition into gas-saturated rock were equal to that measured using a different technique 21 . The end-point relative permeability values extracted from spontaneous imbibition tests were equal to those measured using a steady-state method 21,28 .…”