Pore-scale modeling of ganglion dynamics

Abstract

In this study, a dynamic pore [bodies] and throats model was developed to analyze ganglion dynamics within porous media, transitioning from a bond model to a novel pores and throats framework. Building upon the limitations identified in the bond model and insights gained from direct numerical simulations at TotalEnergies GRC, this new model incorporates innovative techniques for tracking disconnected oil clusters, integrating capillary pressure, fluid distribution at pore intersections, and defining time steps. These enhancements facilitate a more accurate simulation of ganglion dynamics, including break-up and coalescence events, which are essential for understanding multiphase flow. An overview is provided presenting the limitations of the only existing pore network model that contains [limited] ganglion dynamics, as detailed in Boujelben’s thesis (Boujelben, 2017). The discussion highlights the inadequacy of bond models in capturing the complexities of ganglion dynamics due to their oversimplified fluid distribution mechanisms at pore intersections and the competition between frontal and wetting layer displacements as well as between viscous and capillary forces. Direct numerical studies using a Lattice-Boltzmann based simulator at TotalEnergies GRC revealed critical insights into the roles of cohesion and adhesion in fluid distribution at pore junctions. These findings prompted the development of a new pores and throats model, moving away from the phase flag approach to a saturation-based evaluation of multiphase displacements. The new model, detailed in Chapter 5, incorporates novel capillary pressure inclusion based on the content of adjacent pore elements and uses findings from direct numerical simulations to simulate fluid distribution accurately. The model also introduces a novel time-step definition and allows for multiphase injection and flow within each pore element, enhancing the simulation's realism. The model was validated against micromodel experiments and demonstrated independence from network generation, dimensions, and size. The model's efficiency improvements are then illustrated as well as its application in analyzing the effects of various parameters on multiphase displacements. The critical role of ganglion dynamics, including break-up, coalescence, stranding, and mobilization events, in determining the degree of oil displacement by water is highlighted. This research significantly advances the understanding of multiphase flow at the pore-scale, offering a robust framework for future studies and practical applications in enhanced oil recovery and other subsurface fluid dynamics fields.