The influence of fracturing fluids on fracturing processes: A comparison between gas and water

J. H. Wang, D. Elsworth, W. C. Zhu, J. S. Liu, Y. Wu

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Conventional water-based fracturing treatments may not work well for many shale gas reservoirs. This is due to the fact that shale gas formations are much more sensitive to water because of the significant capillary effects and the potentially high contents of swelling clay, each of which may result in the impairment of productivity. As an alternative to water-based fluids, gaseous stimulants not only avoid this potential impairment in productivity, but also conserve water as a resource and may sequester greenhouse gases underground. During the gas fracturing processes, gas will penetrate into the borehole wall due to the low surface tension and low dynamic viscosity of the fluid and the evolution of the fractures results from the coupled phenomena of gas flow, solid deformation and damage. To represent this, a coupled model of rock damage mechanics and gas flow is presented. We investigate the fracturing processes driven by pressurization of gas within a borehole and compare it with water-based fracturing. Simulation results indicate that gas fracturing indeed has a lower breakdown pressure, as observed in experiments, and may develop fractures with greater complexity than those developed with water-based fracturing. We explore the relation between the fracture initiation pressure, breakdown pressure and complexity of fractures to both the interfacial tension and the dynamic viscosity of the fracturing fluids. It is shown that the fracture initiation pressure and breakdown pressure increase and the complexity of the resulting fracture networks decreases with increasing interfacial tension and dynamic viscosity. These conclusions are consistent with experimental observations.

Original languageEnglish (US)
Title of host publication49th US Rock Mechanics / Geomechanics Symposium 2015
PublisherAmerican Rock Mechanics Association (ARMA)
Pages1002-1010
Number of pages9
ISBN (Electronic)9781510810518
StatePublished - Jan 1 2015
Event49th US Rock Mechanics / Geomechanics Symposium - San Francisco, United States
Duration: Jun 29 2015Jul 1 2015

Publication series

Name49th US Rock Mechanics / Geomechanics Symposium 2015
Volume2

Other

Other49th US Rock Mechanics / Geomechanics Symposium
CountryUnited States
CitySan Francisco
Period6/29/157/1/15

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

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