Fingering Instabilities of Multi-Phase Multi-Component Flows in Porous Media

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This research is concerned with the modelling of flows through porous media that involve many fluids that can be in liquid or gas form and that interact with the surrounding solid. Such flows can lead to the development of uneven fronts between the different fluids and result in the growth of complex finger-shaped structures referred to as fingering instabilities. These instabilities are relevant in a wide spectrum of applications that include enhanced and unconventional oil recovery, soil remediation and CO2 sequestration as they affect the flow volumetric sweep and the fluids’ mixing efficiency. In particular the degree of success of many processes used for enhanced oil recovery as well as heavy oil recovery depends on the nature of contact between the resident oil and the fluids used to displace them. In terms of groundwater decontamination, many aquifers are endangered by a variety of pollutants such as hydrocarbons and wastewater from different sources. Typically these contaminants can develop fingering instabilities as they migrate through the water zone. Some of the remediation techniques of the polluted water table are based on hydraulic processes that involve pumping fluids into the table, chemical processes that use pollutants degradation through the injection of reactive fluids or thermal processes that use steam to vent volatile substances. All these decontamination processes can result in fingering instabilities. Finally, in the process of CO2 sequestration that is hoped to help mitigate climate changes, the differences in the viscosity and density of the carbon dioxide as it dissolves into the brine result in fingering instabilities that will ultimately affect the amount of CO2 that is stored in the deep underground. In all these applications, different fluids are present either in liquid or gas phase and as the flow develops, one can witness a variety of interactions between the fluids which consist of many components and the porous medium as well as between the different fluids through mass exchanges and phase changes. Understanding the development of the fingering instabilities for such multi-phase, multi-component flows is crucial for determining the efficiency of processes such as the ones discussed earlier and to optimize them in order to achieve the best outcome. Such an understanding can be reached through a combination of laboratory and field experiments and numerical modelling via computer simulations. The latter approach that we propose to adopt in this study offers the advantage of examining a variety of flow conditions and scenarios that allow exploring situations that are sometimes difficult or too costly to test through experimental measurements. The objective of the proposed research is to develop software capable of analyzing such complex flows and that accounts for the many and intricate interactions between the fluids as they go through phase changes or interact with the solid matrix of the porous medium. Graduate students will be trained in the design and construction of such software which will involve many tasks that require expertise in a variety of disciplines that include engineering, physics, mathematics and computer programming. Furthermore, due to the inherent complexity of the analyzed flows, it is proposed to carry out the study in many stages of increasing complexity and sophistication. In particular, initial studies will involve either multi-component single-phase systems, multi-phase single-component systems or single-component flows that involve phase changes. Ultimately, the developed software should allow the modeling of flow displacements that involve an arbitrary number of components and phases with intricate interactions between the different liquid, gas and solid phases.