Stress-Induced Anomalous Transport in Natural Fracture Networks

Peter K K Kang, Qinghua Lei, Marco Dentz, Ruben Juanes

Research output: Contribution to journalArticle

Abstract

We investigate the effects of geological stress on fluid flow and tracer transport in natural fracture networks. We show the emergence of non-Fickian (anomalous) transport from the interplay among fracture network geometry, aperture heterogeneity, and geological stress. In this study, we extract the fracture network geometry from the geological map of an actual rock outcrop, and we simulate the geomechanical behavior of fractured rock using a hybrid finite-discrete element method. We analyze the impact of stress on the aperture distribution, fluid flow field, and tracer transport properties. Both stress magnitude and orientation have strong effects on the fracture aperture field, which in turn affects fluid flow and tracer transport through the system. We observe that stress anisotropy may cause significant shear dilation along long, curved fractures that are preferentially oriented to the stress loading. This, in turn, induces preferential flow paths and anomalous early arrival of tracers. An increase in stress magnitude enhances aperture heterogeneity by introducing more small apertures, which exacerbates late-time tailing. This effect is stronger when there is higher heterogeneity in the initial aperture field. To honor the flow field with strong preferential flow paths, we extend the Bernoulli Continuous Time Random Walk model to incorporate dual velocity correlation length scales. The proposed upscaled transport model captures anomalous transport through stressed fracture networks and agrees quantitatively with the high-fidelity numerical simulations.

Original languageEnglish (US)
Pages (from-to)4163-4185
Number of pages23
JournalWater Resources Research
Volume55
Issue number5
DOIs
StatePublished - May 1 2019

Fingerprint

fracture network
tracer
fluid flow
preferential flow
flow field
geometry
fracture aperture
discrete element method
dilation
tailings
rock
outcrop
anisotropy
simulation
effect

Cite this

Stress-Induced Anomalous Transport in Natural Fracture Networks. / Kang, Peter K K; Lei, Qinghua; Dentz, Marco; Juanes, Ruben.

In: Water Resources Research, Vol. 55, No. 5, 01.05.2019, p. 4163-4185.

Research output: Contribution to journalArticle

Kang, PKK, Lei, Q, Dentz, M & Juanes, R 2019, 'Stress-Induced Anomalous Transport in Natural Fracture Networks', Water Resources Research, vol. 55, no. 5, pp. 4163-4185. https://doi.org/10.1029/2019WR024944
Kang, Peter K K ; Lei, Qinghua ; Dentz, Marco ; Juanes, Ruben. / Stress-Induced Anomalous Transport in Natural Fracture Networks. In: Water Resources Research. 2019 ; Vol. 55, No. 5. pp. 4163-4185.
@article{94c01d8d03c14174bc8a7149117015f8,
title = "Stress-Induced Anomalous Transport in Natural Fracture Networks",
abstract = "We investigate the effects of geological stress on fluid flow and tracer transport in natural fracture networks. We show the emergence of non-Fickian (anomalous) transport from the interplay among fracture network geometry, aperture heterogeneity, and geological stress. In this study, we extract the fracture network geometry from the geological map of an actual rock outcrop, and we simulate the geomechanical behavior of fractured rock using a hybrid finite-discrete element method. We analyze the impact of stress on the aperture distribution, fluid flow field, and tracer transport properties. Both stress magnitude and orientation have strong effects on the fracture aperture field, which in turn affects fluid flow and tracer transport through the system. We observe that stress anisotropy may cause significant shear dilation along long, curved fractures that are preferentially oriented to the stress loading. This, in turn, induces preferential flow paths and anomalous early arrival of tracers. An increase in stress magnitude enhances aperture heterogeneity by introducing more small apertures, which exacerbates late-time tailing. This effect is stronger when there is higher heterogeneity in the initial aperture field. To honor the flow field with strong preferential flow paths, we extend the Bernoulli Continuous Time Random Walk model to incorporate dual velocity correlation length scales. The proposed upscaled transport model captures anomalous transport through stressed fracture networks and agrees quantitatively with the high-fidelity numerical simulations.",
author = "Kang, {Peter K K} and Qinghua Lei and Marco Dentz and Ruben Juanes",
year = "2019",
month = "5",
day = "1",
doi = "10.1029/2019WR024944",
language = "English (US)",
volume = "55",
pages = "4163--4185",
journal = "Water Resources Research",
issn = "0043-1397",
publisher = "American Geophysical Union",
number = "5",

}

TY - JOUR

T1 - Stress-Induced Anomalous Transport in Natural Fracture Networks

AU - Kang, Peter K K

AU - Lei, Qinghua

AU - Dentz, Marco

AU - Juanes, Ruben

PY - 2019/5/1

Y1 - 2019/5/1

N2 - We investigate the effects of geological stress on fluid flow and tracer transport in natural fracture networks. We show the emergence of non-Fickian (anomalous) transport from the interplay among fracture network geometry, aperture heterogeneity, and geological stress. In this study, we extract the fracture network geometry from the geological map of an actual rock outcrop, and we simulate the geomechanical behavior of fractured rock using a hybrid finite-discrete element method. We analyze the impact of stress on the aperture distribution, fluid flow field, and tracer transport properties. Both stress magnitude and orientation have strong effects on the fracture aperture field, which in turn affects fluid flow and tracer transport through the system. We observe that stress anisotropy may cause significant shear dilation along long, curved fractures that are preferentially oriented to the stress loading. This, in turn, induces preferential flow paths and anomalous early arrival of tracers. An increase in stress magnitude enhances aperture heterogeneity by introducing more small apertures, which exacerbates late-time tailing. This effect is stronger when there is higher heterogeneity in the initial aperture field. To honor the flow field with strong preferential flow paths, we extend the Bernoulli Continuous Time Random Walk model to incorporate dual velocity correlation length scales. The proposed upscaled transport model captures anomalous transport through stressed fracture networks and agrees quantitatively with the high-fidelity numerical simulations.

AB - We investigate the effects of geological stress on fluid flow and tracer transport in natural fracture networks. We show the emergence of non-Fickian (anomalous) transport from the interplay among fracture network geometry, aperture heterogeneity, and geological stress. In this study, we extract the fracture network geometry from the geological map of an actual rock outcrop, and we simulate the geomechanical behavior of fractured rock using a hybrid finite-discrete element method. We analyze the impact of stress on the aperture distribution, fluid flow field, and tracer transport properties. Both stress magnitude and orientation have strong effects on the fracture aperture field, which in turn affects fluid flow and tracer transport through the system. We observe that stress anisotropy may cause significant shear dilation along long, curved fractures that are preferentially oriented to the stress loading. This, in turn, induces preferential flow paths and anomalous early arrival of tracers. An increase in stress magnitude enhances aperture heterogeneity by introducing more small apertures, which exacerbates late-time tailing. This effect is stronger when there is higher heterogeneity in the initial aperture field. To honor the flow field with strong preferential flow paths, we extend the Bernoulli Continuous Time Random Walk model to incorporate dual velocity correlation length scales. The proposed upscaled transport model captures anomalous transport through stressed fracture networks and agrees quantitatively with the high-fidelity numerical simulations.

UR - http://www.scopus.com/inward/record.url?scp=85066892311&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85066892311&partnerID=8YFLogxK

U2 - 10.1029/2019WR024944

DO - 10.1029/2019WR024944

M3 - Article

VL - 55

SP - 4163

EP - 4185

JO - Water Resources Research

JF - Water Resources Research

SN - 0043-1397

IS - 5

ER -