Abstract
Fast synchrotron-based X-ray microtomography was used to image the injection of super-critical \(\hbox {CO}_{2}\) under subsurface conditions into a brine-saturated carbonate sample at the pore-scale with a voxel size of \(3.64\,\upmu \hbox {m}\) and a temporal resolution of 45 s. Capillary pressure was measured from the images by finding the curvature of terminal menisci of both connected and disconnected \(\hbox {CO}_{2}\) clusters. We provide an analysis of three individual dynamic drainage events at elevated temperatures and pressures on the tens of seconds timescale, showing non-local interface recession due to capillary pressure change, and both local and distal (non-local) snap-off. The measured capillary pressure change is not sufficient to explain snap-off in this system, as the disconnected \(\hbox {CO}_{2}\) has a much lower capillary pressure than the connected \(\hbox {CO}_{2}\) both before and after the event. Disconnected regions instead preserve extremely low dynamic capillary pressures generated during the event. Snap-off due to these dynamic effects is not only controlled by the pore topography and throat radius, but also by the local fluid arrangement. Whereas disconnected fluid configurations produced by local snap-off were rapidly reconnected with the connected \(\hbox {CO}_{2}\) region, distal snap-off produced much more long-lasting fluid configurations, showing that dynamic forces can have a persistent impact on the pattern and sequence of drainage events.
Highlights
Multiphase flow through geological systems governs a wide range of processes of global importance, including the flow of oil and gas in reservoirs and carbon dioxide injection into the subsurface in carbon capture and storage
The main goal of our study is to identify individual dynamic drainage events at the porescale, at reservoir conditions, to advance our understanding of these phenomena, and in particular to test some of the assumptions of local capillarity and quasi-static flow used in the formulation of pore-scale network (Valvatne and Blunt 2004; Øren et al 1998) and direct simulation models (Raeini et al 2014a)
We demonstrate how the experimental method developed in this work can be used to describe and explain in detail three pore-scale phenomena during drainage: interface recession due to capillary pressure change, Roof snap-off (Roof 1970) and distal snap-off
Summary
Multiphase flow through geological systems governs a wide range of processes of global importance, including the flow of oil and gas in reservoirs and carbon dioxide injection into the subsurface in carbon capture and storage. Imperial College London, London SW7 2AZ, UK of such systems have been limited to the core-scale. Results relied on either low-intensity laboratory-based or synchrotron X-ray sources, with scans typically taking several hours to acquire. Flow processes at the pore-scale tend to occur on much shorter timescales, meaning that experiments were limited to studying static flow end points, after displacement processes have finished. Highintensity synchrotron light sources have allowed for imaging with a high temporal resolution, sufficient for the imaging of dynamic displacement processes, with pioneering papers by Berg et al (2013) and Armstrong et al (2014) examining Haines jumps and capillary desaturation, respectively
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
