Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

Using X-ray computed microtomography, we have visualized and quantified the in situ structure of a trapped nonwetting phase (oil) in a highly heterogeneous carbonate rock after injecting a wetting phase (brine) at low and high capillary numbers. We imaged the process of capillary desaturation in 3D and demonstrated its impacts on the trapped nonwetting phase cluster size distribution. We have identified a previously unidentified pore-scale event during capillary desaturation. This pore-scale event, described as droplet fragmentation of the nonwetting phase, occurs in larger pores. It increases volumetric production of the nonwetting phase after capillary trapping and enlarges the fluid−fluid interface, which can enhance mass transfer between the phases. Droplet fragmentation therefore has implications for a range of multiphase flow processes in natural and engineered porous media with complex heterogeneous pore spaces

Prediction of Three-Phase Capillary Pressure using a Network Model Anchored to Two-Phase Data

Three-phase capillary pressure is difficult to measure experimentally and therefore has to be estimated by other methods. In this work a network model was applied to generate a consistent set of two-phase and three-phase capillary pressure curves. Experimental data for two-phase, gas-oil and oil-water, capillary pressure from a North Sea reservoir was used in this study. The network model was anchored to the measured two-phase data, and three-phase capillary pressure was constructed. The gas-oil and mercury capillary pressure anchors the pore structure parameters, while water-oil capillary pressure anchors the wettability parameters in the network model. The three-phase capillary pressure is predicted by using the pore structure and wettability found for the two-phase cases as input. The network model quantifies the difference between two-phase and three-phase capillary pressure. In the cases studied the difference between two-phase and three-phase capillary pressure is significant

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

In this paper, we provide a unified approach to a family of integrals of Mellin-Barnes type using distribution theory and Fourier transforms. Interesting features arise in many of the cases which call for the application of pull-backs of distributions via smooth submersive maps defined by Hormander. We derive by this method the integrals of Hecke and Sonine related to various types of Bessel functions which have found applications in analytic and algebraic number theory. (C) 2013 Elsevier GmbH. All rights reserved

3D Stochastic Modelling of Heterogeneous Porous Media: Applications to Reservoir Rocks

The creation of a 3D pore-scale model of a porous medium is often an essential step in quantitatively characterising the medium and predicting its transport properties. Here we describe a new stochastic pore space reconstruction approach that uses thin section images as its main input. The approach involves using a third-order Markov mesh where we introduce a new algorithm that creates the reconstruction in a single scan, thus overcoming the computational issues normally associated with Markov chain methods. The technique is capable of generating realistic pore architecture models (PAMs), and examples are presented for a range of fairly homogenous rock samples as well as for one heterogeneous soil sample. We then apply a Lattice–Boltzmann (LB) scheme to calculate the permeabilities of the PAMs, which in all cases closely match the measured values of the original samples. We also develop a set of software methods – referred to as pore analysis tools (PATs) – to quantitatively analyse the reconstructed pore systems. These tools reveal the pore connectivity and pore size distribution, from which we can simulate the mercury injection process, which in turn reproduces the measured curves very closely. Analysis of the topological descriptors reveals that a connectivity function based on the specific Euler number may serve as a simple predictor of the threshold pressure for geo-materials