Abstract
Hypothesis: The wetting behaviour is a key property of a porous medium that controls hydraulic conductivity in multiphase flow. While many porous materials, such as hydrocarbon reservoir rocks, are initially wetted by the aqueous phase, surface active components within the non-wetting phase can alter the wetting state of the solid. Close to the saturation endpoints wetting phase fluid films of nanometre thickness impact the wetting alteration process. The properties of these films depend on the chemical characteristics of the system. Here we demonstrate that surface texture can be equally important and introduce a novel workflow to characterize the wetting state of a porous medium. Experiments: We investigated the formation of fluid films along a rock surface imaged with atomic force microscopy using ζ-potential measurements and a computational model for drainage. The results were compared to spontaneous imbibition test to link sub-pore-scale and core-scale wetting characteristics of the rock. Findings: The results show a dependency between surface coverage by oil, which controls the wetting alteration, and the macroscopic wetting response. The surface-area coverage is dependent on the capillary pressure applied during primary drainage. Close to the saturation endpoint, where the change in saturation was minor, the oil-solid contact changed more than 80%.
Original language | English |
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Pages (from-to) | 159-169 |
Number of pages | 11 |
Journal | Journal of Colloid and Interface Science |
Volume | 562 |
DOIs | |
Publication status | Published - 7 Mar 2020 |
Externally published | Yes |
Funding
We would like to acknowledge UGCT, Ghent, Belgium for support for the spontaneous imbibition experiment. Furthermore, we would like to acknowledge Alex Schwing and Rob Neiteler for the design of the setup and instrumentation, Hilbert van der Linde for sample preparation. Jos Pureveen, Willie Schermer and Len van Gelder for characterizing the crude oil. Ryan Armstrong and James McClure, Matthew Leivers, Tannaz Pak, Frans Korndorffer, Ove Wilson, the Shell Digital Rock team at Imperial and Shell and the team from Math2Market for helpful discussions. We gratefully acknowledge Shell Global Solutions International B.V., Netherlands for funding and permission to publish this work. The spontaneous imbibition data is available from Bartels et al. [109] : ( https://www.digitalrocksportal.org/projects/188 ). The surface structure of Ketton rock from Rücker et al. [113] : ( https://www.digitalrocksportal.org/projects/231 ).
Keywords
- Atomic force microscopy (AFM)
- Capillary pressure
- Core initialization
- Disjoining pressure
- Surface roughness
- Wetting