Model for Residual Saturations and Capillary Imbibition and Drainage Pressures in Granular Materials
A pore saturation model expresses the capillary pressure as a function of a characteristic pore pressure and the wetting phase saturation. Singularity analyses of the total energies of the wetting and nonwetting phases give the residual saturations for the two phases. The total energy consists of a potential term and a work term associated with the effective pressure gradient for each phase. The derived residual wetting saturation is 0.236, and the derived residual nonwetting saturation is 0.884. The model includes separate pressures for imbibition and drainage to account for capillary hysteresis. In the model, the pressure gradient for the wetting phase defines the imbibition pressure, and the nonwetting phase pressure gradient defines the drainage pressure. At the residual nonwetting saturation, the two pressures differ by the characteristic pore pressure. The two pressures coincide at a critical minimum saturation of 0.301. The model also includes an entry head to account for the minimum force required for drainage to begin. The model uses a single fitting parameter, a characteristic pore pressure, which can be related to a characteristic pore diameter.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC09-96SR18500
- OSTI ID:
- 835062
- Report Number(s):
- WSRC-MS-2003-00793, Rev. 1; TRN: US200435%%20
- Journal Information:
- Transport in Porous Media, Other Information: PBD: 1 Nov 2004
- Country of Publication:
- United States
- Language:
- English
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