Marek Krzysztof Misztal, Niels Bohr Institute – University of Copenhagen

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Atmospheric complexity > Complex Fluids Seminar > 2017 > Marek Krzysztof Miszta...

Marek Krzysztof Misztal, Niels Bohr Institute

Flow rate fluctuations in two-phase, pore-scale flows.

 The passing decade has seen an advance in X-ray micro- and nanotomography techniques, providing accurate, high resolution 3d images of pore structures of reservoir rocks. In comparison to traditional experimental methods, tomographic data might be used in fast numerical estimates of petrophysical parameters of reservoir rocks. Among these parameters, porosity and absolute permeability are easy to estimate numerically and upscale, and show good agreement with experimental measurements. In contrast, accurate numerical measurements of two phase flow properties (relative permeability and capillary pressure curves) based on pore-scale data are less straight-forward, and marred by significantly larger errors. This is partially due to the fact that two phase flows depend not only on the geometry of the porous network, but also on the spatial distribution of the two fluids. Further, experimental measurements of relative permeabilities are performed on mesoscopic samples, and rely on spatial and temporal averaging of the partial flow rates. However, at the pore scale, the flow is dominated by the capillary effects, which manifest itself by significant fluctuations of the total and partial flow rates of the fluid. 
In our work, we attempt to assess the usefulness and accuracy of the numerical, pore-scale measurements of relative permeability, using the free-energy lattice Boltzmann method for binary flows. We perform our study by quantifying flow rate fluctuations in a number of artificial and natural porous samples for varying driving forces and initial fluid distributions, with the goal of determining the sample size and simulation length required to obtain reliable results.