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Title: Discontinuities in effective permeability due to fracture percolation

Abstract

Motivated by a triaxial coreflood experiment with a sample of Utica shale where an abrupt jump in permeability was observed, possibly due to the creation of a percolating fracture network through the sample, we perform numerical simulations based on the experiment to characterize how the effective permeability of otherwise low-permeability porous media depends on fracture formation, connectivity, and the contrast between the fracture and matrix permeabilities. While a change in effective permeability due to fracture formation is expected, the dependence of its magnitude upon the contrast between the matrix permeability and fracture permeability and the fracture network structure is poorly characterized. We use two different high-fidelity fracture network models to characterize how effective permeability changes as percolation occurs. The first is a dynamic two-dimensional fracture propagation model designed to mimic the laboratory settings of the experiment. The second is a static three-dimensional discrete fracture network (DFN) model, whose fracture and network statistics are based on the fractured sample of Utica shale. Once the network connects the inflow and outflow boundaries, the effective permeability increases non-linearly with network density. In most networks considered, a jump in the effective permeability was observed when the embedded fracture network percolated. We characterize how themore » magnitude of the jump, should it occur, depends on the contrast between the fracture and matrix permeabilities. For small contrasts between the matrix and fracture permeabilities the change is insignificant. However, for larger contrasts, there is a substantial jump whose magnitude depends non-linearly on the difference between matrix and fracture permeabilities. A power-law relationship between the size of the jump and the difference between the matrix and fracture permeabilities is observed. In conclusion, the presented results underscore the importance of fracture network topology on the upscaled properties of the porous medium in which it is embedded.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1419753
Report Number(s):
LA-UR-17-23142
Journal ID: ISSN 0167-6636
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Mechanics of Materials
Additional Journal Information:
Journal Volume: 119; Journal Issue: C; Journal ID: ISSN 0167-6636
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Computer Science; Earth Sciences; Energy Sciences; Mathematics; Flow in porous media; Discrete fracture networks; Percolation

Citation Formats

Hyman, Jeffrey De'Haven, Karra, Satish, Carey, James William, Gable, Carl Walter, Viswanathan, Hari S., Rougier, Esteban, and Lei, Zhou. Discontinuities in effective permeability due to fracture percolation. United States: N. p., 2018. Web. doi:10.1016/j.mechmat.2018.01.005.
Hyman, Jeffrey De'Haven, Karra, Satish, Carey, James William, Gable, Carl Walter, Viswanathan, Hari S., Rougier, Esteban, & Lei, Zhou. Discontinuities in effective permeability due to fracture percolation. United States. doi:10.1016/j.mechmat.2018.01.005.
Hyman, Jeffrey De'Haven, Karra, Satish, Carey, James William, Gable, Carl Walter, Viswanathan, Hari S., Rougier, Esteban, and Lei, Zhou. 2018. "Discontinuities in effective permeability due to fracture percolation". United States. doi:10.1016/j.mechmat.2018.01.005.
@article{osti_1419753,
title = {Discontinuities in effective permeability due to fracture percolation},
author = {Hyman, Jeffrey De'Haven and Karra, Satish and Carey, James William and Gable, Carl Walter and Viswanathan, Hari S. and Rougier, Esteban and Lei, Zhou},
abstractNote = {Motivated by a triaxial coreflood experiment with a sample of Utica shale where an abrupt jump in permeability was observed, possibly due to the creation of a percolating fracture network through the sample, we perform numerical simulations based on the experiment to characterize how the effective permeability of otherwise low-permeability porous media depends on fracture formation, connectivity, and the contrast between the fracture and matrix permeabilities. While a change in effective permeability due to fracture formation is expected, the dependence of its magnitude upon the contrast between the matrix permeability and fracture permeability and the fracture network structure is poorly characterized. We use two different high-fidelity fracture network models to characterize how effective permeability changes as percolation occurs. The first is a dynamic two-dimensional fracture propagation model designed to mimic the laboratory settings of the experiment. The second is a static three-dimensional discrete fracture network (DFN) model, whose fracture and network statistics are based on the fractured sample of Utica shale. Once the network connects the inflow and outflow boundaries, the effective permeability increases non-linearly with network density. In most networks considered, a jump in the effective permeability was observed when the embedded fracture network percolated. We characterize how the magnitude of the jump, should it occur, depends on the contrast between the fracture and matrix permeabilities. For small contrasts between the matrix and fracture permeabilities the change is insignificant. However, for larger contrasts, there is a substantial jump whose magnitude depends non-linearly on the difference between matrix and fracture permeabilities. A power-law relationship between the size of the jump and the difference between the matrix and fracture permeabilities is observed. In conclusion, the presented results underscore the importance of fracture network topology on the upscaled properties of the porous medium in which it is embedded.},
doi = {10.1016/j.mechmat.2018.01.005},
journal = {Mechanics of Materials},
number = C,
volume = 119,
place = {United States},
year = 2018,
month = 1
}

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