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Title: Modelling multiphase flow through micro-CT images of the pore space
Author: Qaseminejad Raeini, Ali
ISNI:       0000 0004 2741 8108
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2013
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We present a numerical method for modelling two-phase flow through porous media directly at the pore scale. The volume of fluid method is used to capture the interface motion. The volume of fluid equation and the incompressible Navier-Stokes equations are discretised by the finite volume method using a single fluid methodology, with a discontinuity in the phase properties. Capillary forces are calculated using a new semi-sharp formulation and filtered, to allow for simulations at low capillary numbers and avoid non-physical velocities. They are applied into the Navier-Stokes equations using a semi-implicit formulation, which allows larger time steps at low capillary numbers. The numerical method is verified on several test cases, demonstrating its efficiency, stability and accuracy in modelling multiphase flow through porous media with complex interface motion and irregular solid boundaries. We present two-phase flow simulations on simple pore geometries and study the mechanisms controlling two-phase flow at the pore scale. Particularly, we study the effect of geometry and flow rate on trapping and mobilization of the non-wetting-phase. We introduce a new concept to upscale the subpore-scale forces and find the relations between the flow and the pore-scale pressure drops. These information can be used as input to pore-network models. As an example, we applied this concept to predict the threshold capillary number to prevent trapping during imbibition. Furthermore, we present two-phase flow simulations on two micro-CT images of porous media and show the effect of capillary number on the flow pattern, the trapped non-wetting phase saturation and blob sizes. We present a rigorous approach to relate the pore-scale forces controlling the flow to the Darcy-scale parameters and use it to obtain relative permeability curves. Overall, this thesis provides a methodology for a detailed pore-scale analysis of multiphase flow, serving as a rigorous foundation for large-scale modelling and prediction.
Supervisor: Bijeljic, Branko ; Blunt, Martin Sponsor: Imperial College London
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available