Propagation of gravity currents in heterogeneous porous and fractured media

Propagation of gravity currents in heterogeneous porous and fractured media

Gravity current (GC) is a physical phenomenon appearing in different environmental and industrial discipline. Despite investigation during the past decades, yet unanswered questions remain, pointing at a need for more study. Such questions bring challenge to the spotlight in field operations like intrusion or injection of fluids in geologic formations, Co2 sequestration or H2 storage, in which understanding the process is of importance to predict and simulate the underground flow, its propagation and the fate of the current. Further advancement would demands a clear view of how underground heterogeneity and existence of porous and fractured medium affect the propagation of a GC. Heterogeneity map are hard to achieve most of the time, due to the unpredictable nature of underground and expensive methods for geological sampling and investigations, hence the common approach is modelling.Heterogeneity affects GCs in terms of spatially or temporally variable boundary conditions, topographic boundaries, and medium properties, such as porosity, hydraulic conductivity, fracture aperture, specific storage, and saturation. As to medium properties, the quantity varying the most is hydraulic conductivity K or permeability k, which spans several orders of magnitude. Variations may be deterministic or stochastic. While the first area is mostly covered by past literature works, the second area still needs investigation despite four decades of research.

This proposal aims at investigating the effects of heterogeneity on the propagation of viscous gravity currents in porous and fractured media. More specifically, the aim of this proposal is to: i) further investigate the effect of deterministic heterogeneity by examining relevant topographic effects not covered by the literature; ii) delve into gravity currents in heterogeneous domains where the permeability is represented as a random field.

1, Developing an analytical model for current propagation with different variable (topography, boundary conditions, permeability). 2, Build a numerical model which verified by the analytical one, also can be used for testing it. Moreover, visualizing the flow in heterogenous media is another objective. 3, Use laboratory equipment to test the previous steps.