The visualization of the pore-scale physics of hydrocarbon recovery from reservoirs

This paper presents some of the microscopic pore-level modelling studies carried out at Imperial College. Although we have directed our research towards hydrocarbon reservoirs, our findings are also pertinent to groundwater hydrology, soil science, wastewater disposal, etc., or other applications involving multiphase flow in porous media. Our aims are to gain the needed fuller understanding of pore-scale reservoir behaviour, including the displacement, entrapment and mobilization mechanisms involved in miscible and immiscible fluid systems, with or without mass-transfer or particle movements. The opaque nature of porous media means that it is normally impossible to observe where the fluids are, and how their distribution is modified under flow conditions. Microvisual modelling, using transparent 2D models representing the rock structure is one way that fluid distributions and movements can be observed and the physics unravelled. We have developed novel visual micromodel techniques, and in this paper we highlight a few recent fascinating examples of some of our qualitative and quantitative work. We illustrate important pore-scale events, in particular how wettability and fluid morphology affect the electrical resistivity of partially saturated rocks and various multiphase flow mechanics including low tension flow, depressurization, gel treatment (partial flow blocking) and crystal scale deposits. We also indicate how these events can affect reservoir performance. physical processes occurring at the pore scale is therefore needed in order to formulate suitable mathematical models for predicting reservoir performance.