Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

Abstract

X-ray microtomography was used to image, at a resolution of 6.6 µm, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space of a carbonate rock at pressures and temperatures representative of typical formations used for CO 2 storage. Chemical equilibrium between the CO 2 , brine and rock phases was maintained using a high pressure high temperature reactor, replicating conditions far away from the injection site. Fluid flow was controlled using high pressure high temperature syringe pumps. To maintain representative in-situ conditions within the micro-CT scanner a carbon fiber high pressure micro-CT coreholder was used. Diffusive CO 2 exchange across the confining sleeve from the pore-space of the rock to the confining fluid was prevented by surrounding the core with a triple wrap of aluminum foil. Reconstructed brine contrast was modeled using a polychromatic x-ray source, and brine composition was chosen to maximize the three phase contrast between the two fluids and the rock. Flexible flow lines were used to reduce forces on the sample during image acquisition, potentially causing unwanted sample motion, a major shortcoming in previous techniques. An internal thermocouple, placed directly adjacent to the rock core, coupled with an external flexible heating wrap and a PID controller was used to maintain a constant temperature within the flow cell. Substantial amounts of CO 2 were trapped, with a residual saturation of 0.203 ± 0.013, and the sizes of larger volume ganglia obey power law distributions, consistent with percolation theory.

Analysis of high‐resolution X‐ray computed tomography images of Bentheim sandstone under elevated confining pressures

“…However, high-resolution CT imaging of rocks under elevated confining pressures is still a technical challenge. Several groups are working towards this direction (e.g., Kawakata et al 1997;Watanabe et al 2011;Andrew, Bijeljic, and Blunt 2015).…”

The Visual and Quantitative Study of the Microoccurrence of Irreducible Water at the Pore and Throat System in a Low-Permeability Sandstone Reservoir by Using Microcomputerized Tomography

“…Median filtration method based on a nonlinear signal processing was used to minimize the noise in the scanning images. More specifically, the filtering mechanism is detailed in Andrew's dissertation [33]. The images before and after median filtration are shown in Figure 3.…”

Review of studies on pore-network modeling of wettability effects on waterflood oil recovery

“…Complexity of the pore geometry has led to the development of many experimental, theoretical, analytical and numerical methods for studying transport and fluid flow processes in porous media (Sallès et al, 1993;Liou, 2005;Wang et al, 2016;Meakin et al, 2007;Chatzis and Dullien, 2009;Sun et al, 2012a;Raeini et al, 2012;Karadimitriou and Hassanizadeh, 2012;Miyan and Pant, 2015;Andrew et al, 2015;Noetinger et al, 2016). Measurement techniques involving the use of X-ray and neutron scattering, scanning electron microscopy (SEM), transmission electron microscopy (TEM), focused ion beam milling (FIBM), QEMSCAN imaging, nuclear magnetic resonance (NMR) and others are usually expensive and time consuming, with accuracy of obtained data limited by sample preparation methods, experimental setup, conditions and procedures.…”