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Image-based micro-continuum model for gas flow in organic-rich shale rock.
- Source :
-
Advances in Water Resources . Dec2018, Vol. 122, p70-84. 15p. - Publication Year :
- 2018
-
Abstract
- Abstract The physical mechanisms that control the flow dynamics in organic-rich shale are not well understood. The challenges include nanometer-scale pores and multiscale heterogeneity in the spatial distribution of the constituents. Recently, digital rock physics (DRP), which uses high-resolution images of rock samples as input for flow simulations, has been used for shale. One important issue with images of shale rock is sub-resolution porosity (nanometer pores below the instrument resolution), which poses serious challenges for instruments and computational models. Here, we present a micro-continuum model based on the Darcy–Brinkman–Stokes framework. The method couples resolved pores and unresolved nano-porous regions using physics-based parameters that can be measured independently. The Stokes equation is used for resolved pores. The unresolved nano-porous regions are treated as a continuum, and a permeability model that accounts for slip-flow and Knudsen diffusion is employed. Adsorption/desorption and surface diffusion in organic matter are also accounted for. We apply our model to simulate gas flow in a high-resolution 3D segmented image of shale. The results indicate that the overall permeability of the sample (at fixed pressure) depends on the time scale. Early-time permeability is controlled by Stokes flow, while the late-time permeability is controlled by non-Darcy effects and surface-diffusion. [ABSTRACT FROM AUTHOR]
- Subjects :
- *SHALE
*SHALE gas
*GAS flow
*NANOPOROUS materials
*PERMEABILITY
Subjects
Details
- Language :
- English
- ISSN :
- 03091708
- Volume :
- 122
- Database :
- Academic Search Index
- Journal :
- Advances in Water Resources
- Publication Type :
- Academic Journal
- Accession number :
- 132970267
- Full Text :
- https://doi.org/10.1016/j.advwatres.2018.10.004