Abstract
With the advancement of high-resolution three-dimensional X-ray imaging, it is now possible to directly calculate the curvature of the interface of two phases extracted from segmented CT images during two-phase flow experiments to derive capillary pressure. However, there is an inherent difficulty of this image-based curvature measurement: the use of voxelized image data for the calculation of curvature can cause significant errors. To address this, we first perform two-phase direct numerical simulations to obtain the oil and water phase distribution, the exact location of the interface, and local fluid pressure. We then investigate a method to compute curvature on the oil/water interface. The interface is defined in two ways. In one case the simulated interface which has a sub-resolution smoothness is used, while the other is a smoothed interface which is extracted from synthetic segmented data based on the simulated phase distribution. Computed mean curvature on these surfaces are compared with that obtained from the fluid pressure computed directly in the simulation. We discuss the accuracy of image-based curvature measurements for the calculation of capillary pressure and propose the best way to extract an accurate curvature measurement, quantifying the likely uncertainties.
Highlights
Capillary pressure, Pc, is a pressure discontinuity across the interface between oil and water, defined as Pc = Po−Pw, where Po and Pw are the pressures of oil and water phase, respectively
Armstrong et al [1] demonstrated this approach using synchrotron-based tomographic datasets of oil/water drainage and imbibition cycles on a bead pack structure [2]. They compared the capillary pressure obtained from curvature measurements with that obtained from pressure transducers
We investigate the accuracy of curvature measurement on the basis of pore-by-pore comparison using direct numerical simulations of two-phase flow
Summary
Armstrong et al [1] demonstrated this approach using synchrotron-based tomographic datasets of oil/water drainage and imbibition cycles on a bead pack structure [2]. They compared the capillary pressure obtained from curvature measurements with that obtained from pressure transducers. There is an inherent difficulty of this imagebased curvature measurement: the use of voxelized image data for the calculation of curvature can cause significant errors, resulting in a wide range of measured values, with some negative curvature values, which are not expected in a water-wet system It is not clear how the distribution of measured curvature values represents the true range of local capillary pressure
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.
