Energy conversion reveals regime transition of imbibition in a rough fracture
Abstract
Depending on the interplay between capillary and viscous forces, imbibition involves capillary and capillary-viscous regimes. Previous studies focused on capillary regime, lacking a fundamental understanding of regime transition. Here we study the transition via imbibition experiments in a rough fracture. By analyzing energy balance in the multiphase-flow system enabled by real-time imaging, we find a fundamental link between imbibition regime transition and energy conversion. In capillary regime, surface energy is partially transformed into external work and an amount of 51-58% is dissipated via local rapid, irreversible events; while in capillary-viscous regime, surface energy together with external work is transformed into kinetic and dissipated energies. This transition, in terms of critical capillary number, is evidenced by quantitative analysis of invasion morphologies including fractal dimension, saturation and displacement front evolutions. Our work proposes a methodology to determine imbibition regime transition, and further elucidates the underlying mechanisms at local scale controlling fluid-displacement patterns.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H41K2213H
- Keywords:
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- 1832 Groundwater transport;
- HYDROLOGYDE: 1859 Rocks: physical properties;
- HYDROLOGYDE: 1878 Water/energy interactions;
- HYDROLOGYDE: 1895 Instruments and techniques: monitoring;
- HYDROLOGY