Correlation of the multiphase flow coefficients of ...

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XVI International Conference on Computational Methods in Water Resources (CMWR-XVI) Ingeniørhuset

Correlation of the multiphase flow coefficients of porous media with wettability: A pore network approach
Paper
Author:Christos Tsakiroglou <ctsakir@iceht.forth.gr> (FORTH / ICE-HT, Stadiou street, Platani, P.O.Box 1414, GR-26504 Patras, Greece)
Presenter:Christos Tsakiroglou <ctsakir@iceht.forth.gr> (FORTH / ICE-HT, Stadiou street, Platani, P.O.Box 1414, GR-26504 Patras, Greece)
Date: 2006-06-18     Track: General Sessions     Session: General
DOI:10.4122/1.1000000727
DOI:10.4122/1.1000000728

Information concerning the capillary pressure and relative permeability curves of porous media is required by the multiphase flow simulators, developed to model NAPL migration in the subsurface. Earlier experimental and theoretical studies have revealed that both capillary pressure and relative permeability functions are strongly affected by the solid surface wettability, which is commonly quantified by the contact angle. However, there is still an ambiguity regarding the capillary pressure and relative permeability functions of intermediate-wet pore systems (contact angle ~ 70o-120o). In the present work, a pore-and-throat network including fractal roughness features along its surface is employed to simulate primary drainage and secondary imbibition by accounting for the quasistatic motion of menisci in pores and throats and varying the contact angle from 0o (strongly water-wet conditions) to 180o (strongly oil-wet conditions). The roughness features of pores and throats are circular cones and triangular prisms, respectively. The angle of sharpness of these features is decided by the specific surface area, and defines a range of contact angles within which the cross-section of the throat or pore is occupied entirely by one fluid (conditions of intermediate wettability). In contrast, outside this range, both fluids may coexist in a pore or throat. Such differences on the fluid distribution at the pore level may have pronounced effects on the calculated effective two-phase flow coefficients and may interpret their non-linear variation with the contact angle. The simulator is used to calculate the capillary pressure and relative permeability curves of a porous medium as the pore system transits from strongly water-wet or strongly oil-wet to intermediate-wet conditions, and interpret relevant experimental results collected from the literature.