Controls of natural fractures on the texture of hydraulic fractures in rock

Xianyu Zhao, Tao Wang, Derek Elsworth, Yunlong He, Wei Zhou, Li Zhuang, Jun Zeng, Suifeng Wang

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Hydraulic fracturing plays an important role in the exploitation of oil, shale gas and coal seam gas resources – all of which contain natural fractures. We systematically explore the role of the pre-existing texture of such natural fractures on the form of the resulting stimulated reservoir volume (SRV). A blocky discrete element model (DEM) coupled with fluid flow is used to explore this response. Numerical predictions for the evolution of fluid pressure and fracture width at the well are compared with first-order analytical approximations of the zero-toughness solution (FMO). We then construct four typical joint system models separately comprising orthogonal, staggered, diagonal and randomly oriented joints and conduct the virtual hydraulic fracturing simulations via DEM. This defines the influence of structure on breakdown pressure and fracture propagation and allows the analysis of the main factors that influence behavior and resulting SRV. Results for the four forms of jointed rock mass show that: (1) the aggregate/mean extension direction of the fractures is always along the direction of the maximum principal stress but significant deviations may result from the pre-existing fractures; (2) there are negative correlations between the maximum fracture aperture with both Poisson ratio and elastic modulus, but the breakdown pressure is only weakly correlated with Poisson ratio and elastic modulus; (3) an increase in injection rate results in a broader fracture process zone extending orthogonal to the principal fracture, and the breakdown pressure and interior fracture aperture also increase; (4) an increase in fluid viscosity makes the fractures more difficult to extend, and the breakdown pressure and interior fracture aperture both increase accordingly.

Original languageEnglish (US)
Pages (from-to)616-626
Number of pages11
JournalJournal of Petroleum Science and Engineering
Volume165
DOIs
StatePublished - Jun 1 2018

Fingerprint

Textures
texture
Rocks
Hydraulics
fracture aperture
rock
Poisson ratio
elastic modulus
Hydraulic fracturing
fracture propagation
hydraulic fracturing
oil shale
fluid pressure
Elastic moduli
coal seam
fluid flow
Oil shale
Fluids
viscosity
Toughness

All Science Journal Classification (ASJC) codes

  • Fuel Technology
  • Geotechnical Engineering and Engineering Geology

Cite this

Zhao, Xianyu ; Wang, Tao ; Elsworth, Derek ; He, Yunlong ; Zhou, Wei ; Zhuang, Li ; Zeng, Jun ; Wang, Suifeng. / Controls of natural fractures on the texture of hydraulic fractures in rock. In: Journal of Petroleum Science and Engineering. 2018 ; Vol. 165. pp. 616-626.
@article{748368ec33c344138ae04b4e43d93707,
title = "Controls of natural fractures on the texture of hydraulic fractures in rock",
abstract = "Hydraulic fracturing plays an important role in the exploitation of oil, shale gas and coal seam gas resources – all of which contain natural fractures. We systematically explore the role of the pre-existing texture of such natural fractures on the form of the resulting stimulated reservoir volume (SRV). A blocky discrete element model (DEM) coupled with fluid flow is used to explore this response. Numerical predictions for the evolution of fluid pressure and fracture width at the well are compared with first-order analytical approximations of the zero-toughness solution (FMO). We then construct four typical joint system models separately comprising orthogonal, staggered, diagonal and randomly oriented joints and conduct the virtual hydraulic fracturing simulations via DEM. This defines the influence of structure on breakdown pressure and fracture propagation and allows the analysis of the main factors that influence behavior and resulting SRV. Results for the four forms of jointed rock mass show that: (1) the aggregate/mean extension direction of the fractures is always along the direction of the maximum principal stress but significant deviations may result from the pre-existing fractures; (2) there are negative correlations between the maximum fracture aperture with both Poisson ratio and elastic modulus, but the breakdown pressure is only weakly correlated with Poisson ratio and elastic modulus; (3) an increase in injection rate results in a broader fracture process zone extending orthogonal to the principal fracture, and the breakdown pressure and interior fracture aperture also increase; (4) an increase in fluid viscosity makes the fractures more difficult to extend, and the breakdown pressure and interior fracture aperture both increase accordingly.",
author = "Xianyu Zhao and Tao Wang and Derek Elsworth and Yunlong He and Wei Zhou and Li Zhuang and Jun Zeng and Suifeng Wang",
year = "2018",
month = "6",
day = "1",
doi = "10.1016/j.petrol.2018.02.047",
language = "English (US)",
volume = "165",
pages = "616--626",
journal = "Journal of Petroleum Science and Engineering",
issn = "0920-4105",
publisher = "Elsevier",

}

Controls of natural fractures on the texture of hydraulic fractures in rock. / Zhao, Xianyu; Wang, Tao; Elsworth, Derek; He, Yunlong; Zhou, Wei; Zhuang, Li; Zeng, Jun; Wang, Suifeng.

In: Journal of Petroleum Science and Engineering, Vol. 165, 01.06.2018, p. 616-626.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Controls of natural fractures on the texture of hydraulic fractures in rock

AU - Zhao, Xianyu

AU - Wang, Tao

AU - Elsworth, Derek

AU - He, Yunlong

AU - Zhou, Wei

AU - Zhuang, Li

AU - Zeng, Jun

AU - Wang, Suifeng

PY - 2018/6/1

Y1 - 2018/6/1

N2 - Hydraulic fracturing plays an important role in the exploitation of oil, shale gas and coal seam gas resources – all of which contain natural fractures. We systematically explore the role of the pre-existing texture of such natural fractures on the form of the resulting stimulated reservoir volume (SRV). A blocky discrete element model (DEM) coupled with fluid flow is used to explore this response. Numerical predictions for the evolution of fluid pressure and fracture width at the well are compared with first-order analytical approximations of the zero-toughness solution (FMO). We then construct four typical joint system models separately comprising orthogonal, staggered, diagonal and randomly oriented joints and conduct the virtual hydraulic fracturing simulations via DEM. This defines the influence of structure on breakdown pressure and fracture propagation and allows the analysis of the main factors that influence behavior and resulting SRV. Results for the four forms of jointed rock mass show that: (1) the aggregate/mean extension direction of the fractures is always along the direction of the maximum principal stress but significant deviations may result from the pre-existing fractures; (2) there are negative correlations between the maximum fracture aperture with both Poisson ratio and elastic modulus, but the breakdown pressure is only weakly correlated with Poisson ratio and elastic modulus; (3) an increase in injection rate results in a broader fracture process zone extending orthogonal to the principal fracture, and the breakdown pressure and interior fracture aperture also increase; (4) an increase in fluid viscosity makes the fractures more difficult to extend, and the breakdown pressure and interior fracture aperture both increase accordingly.

AB - Hydraulic fracturing plays an important role in the exploitation of oil, shale gas and coal seam gas resources – all of which contain natural fractures. We systematically explore the role of the pre-existing texture of such natural fractures on the form of the resulting stimulated reservoir volume (SRV). A blocky discrete element model (DEM) coupled with fluid flow is used to explore this response. Numerical predictions for the evolution of fluid pressure and fracture width at the well are compared with first-order analytical approximations of the zero-toughness solution (FMO). We then construct four typical joint system models separately comprising orthogonal, staggered, diagonal and randomly oriented joints and conduct the virtual hydraulic fracturing simulations via DEM. This defines the influence of structure on breakdown pressure and fracture propagation and allows the analysis of the main factors that influence behavior and resulting SRV. Results for the four forms of jointed rock mass show that: (1) the aggregate/mean extension direction of the fractures is always along the direction of the maximum principal stress but significant deviations may result from the pre-existing fractures; (2) there are negative correlations between the maximum fracture aperture with both Poisson ratio and elastic modulus, but the breakdown pressure is only weakly correlated with Poisson ratio and elastic modulus; (3) an increase in injection rate results in a broader fracture process zone extending orthogonal to the principal fracture, and the breakdown pressure and interior fracture aperture also increase; (4) an increase in fluid viscosity makes the fractures more difficult to extend, and the breakdown pressure and interior fracture aperture both increase accordingly.

UR - http://www.scopus.com/inward/record.url?scp=85042936922&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85042936922&partnerID=8YFLogxK

U2 - 10.1016/j.petrol.2018.02.047

DO - 10.1016/j.petrol.2018.02.047

M3 - Article

VL - 165

SP - 616

EP - 626

JO - Journal of Petroleum Science and Engineering

JF - Journal of Petroleum Science and Engineering

SN - 0920-4105

ER -