Darcy-scale dynamics of microscopically fluctuating interfaces

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In a recent Government report "UK Oil and Gas - Business and Government Action", it is stressed that "70% of British energy requirements [are] still likely to be met by oil and gas into the 2040s", so that strategically "maximizing domestic supplies of oil and gas [...] leads to increased resilience and security for the UK's energy needs when compared with imports". At the same time, according to the World Energy Outlook Report of 2014, existing methods of secondary oil recovery still leave from 30 to 60% of oil unrecovered when an oilfield is abandoned as 'exhausted' and the exploration moves to a new one. This is both inefficient and environmentally unfriendly. To reach the unrecovered oil and reduce the pace of expansion into new oilfields until renewable power generation becomes an economically viable alternative, it is necessary to develop efficient methods of Enhanced Oil Recovery (EOR). EOR is focused on recovering oil blobs trapped in the porous rock, known as 'ganglia', that remain stuck after the water-flooding 'secondary recovery stage'. The aim of EOR is to mobilize the ganglia by some additional physical mechanisms. The opposite problem is carbon dioxide sequestration; a process aimed at reducing the pace of climate change. There, it is absolutely essential that carbon dioxide volumes pumped into a porous layer remain there without escaping back into the atmosphere. In each case, the trial-and-error assessment of the efficiency of recovery or storage is prohibitively expensive, so that here theoreticians have a unique role to play by developing a predictive mathematical model that would reliably describe the conditions for mobilization and the dynamics of mobilized trapped fluid volumes in different porous matrices. The proposed research aims at addressing this dual problem. It has become possible as a result of two recent developments:- an experimental discovery at Schlumberger Gould Research Centre, Cambridge that the ganglia trapped in a porous rock can be mobilized by fluctuations on the scale of the individual pores which can be generated even when the external forcing is steady - a new conceptual framework for describing the propagation of wetting fronts, developed by the project's investigators, which for the first time describes highly unusual ('anomalous') regimes of invasion of liquids into porous solids, that were discovered experimentally two decades ago.The synergy of these two developments opens a way to the first reliable predictive model describing the stability and dynamics of ganglia in porous solids. The potential for the field-transforming changes has been recognized by industry, and Schlumberger, the world's leading supplier of technology solutions for the oil and gas industry, has offered to support the project by releasing its experimental data (conservatively estimated at £715,000 to generate) and the help of its staff to interpret them (£15,000 in the staff time) as well as training of the PDRAs involved in this work. On the theoretical side, the proposed work addresses a number of fundamental research challenges in the mechanics of multiphase systems such as the translation of the pore-scale information into the properties of a macroscopic (Darcy-scale) model and the modelling of transitions in the topology of the flow domain (breakup of ganglia, their coalescence). Advances here will make a significant methodological impact on mechanics of multiphase system well beyond the study of flows in porous media. The degree of novelty and adventure in the proposed research is best illustrated by the fact that, even knowing the two developments listed above that form the basis of the project, it is still impossible to even qualitatively predict the effect of their synergy. If supported and successful, the project offers a step-change advance in our understanding of multiphase systems and, via Schlumberger, an immediate application of results.