Testing predictive value of image-based predictions for two-phase drainage relative permeability

Download files
Access & Terms of Use
open access
Copyright: Hussain, Furqan
Altmetric
Abstract
In the past two decades there have been several attempts to compute relative permeability from high resolution, three-dimensional, X-ray microtomography (micro-CT) images of the microstructure of a natural porous rock. In these attempts, researchers simulated fluid flow directly on the imaged 3D pore space to compute relative permeabilities. They then used laboratory measurements to validate the predictions. Analysis of these works shows a number of shortcomings in those validations. For example: (i) there has been very limited direct comparison between the imaged rock and the rock used in the laboratory tests, i.e. researchers preferred to use the literature data for validation mostly, (iii) there has been image resolution issues that limited prediction accuracy, (iv) there has been limited attempt to use high resolution images of multiple fluids in place and (v) the Lattice-Boltzmann method has instability issues to predict relative permeability at low phase saturations. The purpose of this thesis is to test the predictive value of image-based numerical computations for two-phase, drainage relative permeability using well-defined laboratory measurements. The experimental data represents a steady-state flow of oil and water in strongly water-wet, homogeneous outcrop sandstone (Bentheimer) and covers a full saturation range of both phases. This data is obtained using a standard core sample. Next, a small sister plug is imaged by micro-CT and the steady-state experiments are repeated on this plug for three different saturation distributions. These three saturation distributions are imaged and compared with simulated fluid distributions on the dry image (using the capillary drainage transform CDT method). The comparison shows that CDT-based saturation distributions agree with the actual imaged saturation distributions. Finally, relative permeability computations are made over the CDT-based saturation distributions. The issues experienced in the previous studies such as the image resolution and computational capacity are minimized in this study through using an image of higher resolution and a larger subset. The thesis demonstrates a good agreement between the image-based computations made using the CDT method and the laboratory data. The requirements for a successful prediction using the CDT method are strong wetting conditions and capillary-dominated flow. In order to ensure these conditions, the laboratory tests described in this study employ the plasma technique for cleaning the core plug and use appropriate flow rates for controlling the capillary number. The agreement also confirms that steady-state experimental data is representative for testing image-based predictions. In this thesis, an attempt is made to use high-resolution micro-CT images of multiphase distributions in relative permeability computations. It is found that relative permeabilities are underestimated. This is attributed to snap-off that occurs when the steady-state experiment is stopped for micro-CT imaging and causes the non-wetting phase to be disconnected. As a result, the thesis recommends that both steady-state tests and micro-CT images should be carried out at dynamic conditions for an accurate validation of image-based methods.
Persistent link to this record
Link to Publisher Version
Link to Open Access Version
Additional Link
Author(s)
Hussain, Furqan
Supervisor(s)
Cinar, Yildiray
Arns, Christoph
Pinczewski, Val
Creator(s)
Editor(s)
Translator(s)
Curator(s)
Designer(s)
Arranger(s)
Composer(s)
Recordist(s)
Conference Proceedings Editor(s)
Other Contributor(s)
Corporate/Industry Contributor(s)
Publication Year
2012
Resource Type
Thesis
Degree Type
PhD Doctorate
UNSW Faculty
Files
download whole.pdf 1.94 MB Adobe Portable Document Format
Related dataset(s)