Dr. Marios Valavanides, associate professor at the University of West Attica in Greece, will be our SFB 1313 guest and visit the Institute of Applied Mechanics at the University of Stuttgart. On Tuesday November 26, 2019, he will give a SFB 1313 lecture on "A new theoretical framework for two-phase flows in porous media – Recent advances and prospectives".
Date: November 26, 2019
Time: 5 pm
Place: MML (U 1.003), Pfaffenwaldring 61
Title: "A new theoretical framework for two-phase flows in porous media – Recent advances and prospectives"
Abstract
The DeProF theory for two-phase flow in porous media is built around a hybrid mechanistic/stochastic model [1] that considers the flow as a mixture of constituent flows each with different degree of disconnectedness of the non-wetting phase (NWP). The model accounts all essential pore-scale phenomena on a mechanistic basis and, implementing a stochastic approach, up-scales these into corresponding network-wide cooperative effects. The momentum balance is regulated by the relative intensities of the NWP and WP flows (inducing bulk viscous flow resistances) and the degree of disconnection of the NWP (inducing interfacial capillary resistances). Steady-state conditions settle-in when each dissipative term is counterbalanced by the other two. Viscous and capillary resistances scale differently with the flow conditions, therefore the latter regulate the balance point.
The model takes into account the contribution of all system properties in appropriately reduced numbers; in particular, viscosity disparity versus capillarity, wettability and pore network structure, lead to the derivation of an improved, system-reduced capillary number. Consequently, modeling redundancies associated to the system properties are reduced to a minimum.
Extensive simulations across orders of magnitude in flow conditions and with different fluid systems revealed the underlying, inherent systematic structure of biphasic flows in p.m. [2] and helped deriving a universal scaling function for flow-dependent relative permeabilities [3, 4]. In parallel, energy efficiency analysis revealed a universal flow characteristic, the existence of a unique locus of critical flow conditions whereby the energy efficiency of the process attains locally maximum values [5]. The existence of a unique locus of critical flow conditions opens new perspectives: (a) in deriving universal, energy efficiency and relative permeability maps; (b) in developing methodologies for the normative characterization of biphasic flows, their taxonomic classification and the effective characterization of pore networks [6]; (c) in improving the energy efficiency of pertinent processes (e.g. EOR, filtering, etc.).
The presentation will conclude with a list of open problems and research directions to explore.
References
- Valavanides, M.S., Payatakes, A.C. True-to-mechanismmodel of steady-state two-phase flowin porous media, using decomposition into prototype flows. Water Res.24(3–4), 385–407 (2001), https://doi.org/10.1016/S0309-1708(00)00063-4
- Valavanides, M.S. Flow structure maps for two-phase flow in model pore networks. Predictions based on extensive, DeProF model s Oil Gas Sci. Technol. Rev. IFP Energies nouvelles73 (6), 1-36 (2018), https://doi.org/10.2516/ogst/2017033
- Valavanides, M.S. Universal, true to mechanism, flow dependent relative permeability scaling functional form for steady-state 2-phase flows in p.m. Symposium of the Society of Core Analysts, Trondheim, Norway, 27-30 Aug. 2018, http://users.uniwa.gr/marval/publ/Valavanides_SCA2018_066.pdf
- Valavanides, M.S., Mascle, M., Youssef, S., Vizika, O. Steady-State Two-Phase Flow in Porous Media: Laboratory Validation of Flow Dependent Relative Permeability Scaling. Symposium of the Society of Core Analysts, Pau, France, 26-30 Aug. 2019, http://users.uniwa.gr/marval/publ/Valavanides_etal_SCA2019-005.pdf
- Valavanides, M.S., Totaj, E., Tsokopoulos, M. Energy efficiency characteristics in steady-state relative permeabilitydiagrams of two-phase flow in porous media. Petrol. Sci. Eng.147, 181–201 (2016), https://doi.org/10.1016/j.petrol.2016.04.039
- Valavanides, M.S. Review of steady-state two-phase flow in porous media: independent variables, universal energy efficiency map, critical flow conditions, effective characterization of flow and pore network. in Porous Media123 (1), 42-99 (2018), https://doi.org/10.1007/S11242-018-1026-1