Dynamic pore-network modelling for two-phase flow

Time:	January 13, 2009
Lecturer:	Vahid Joekar-Niasar Environmental Hydrogeology Group, University of Utrecht
Venue:	Pfaffenwaldring 61, Raum U1.003 (MML), Universität Stuttgart
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Pore-network models have been used for many theoretical and practical applications. They are mainly categorized under quasi-static and dynamic pore-network models. We will show that quasi-static pore-network models can be used as a predictive tool for laboratorial experiments and also as an investigation tool in theoretical studies.

Then dynamic pore-network models will be introduced, which have been used much less compared to quasi-static ones. We have developed a new dynamic pore-network model for studying transient behavior of average capillary pressure and saturation. Traditional two-phase flow models assume that macroscopic phase pressure difference is a function of macroscopic saturation. However, under dynamic conditions, the difference of macroscopic phase pressures is known to be a function of time rate of saturation change.

Significant difference between our dynamic pore network model and conventional dynamic pore-network models is in solving the pressure field. Pressure field is solved for each phase separately and they are related to each other by local capillary pressure which is a function of local interface curvature.

Finally we have simulated a drainage experiment for different viscosity ratios. We have studied functionality of the dynamic coefficient as a function of saturation and viscosity ratios. In addition, effect of global pressure difference on trapping mechanism and invading front topology has been studied.