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On the risk of hydraulic fracturing in CO2 geological storage

Abstract

We present a contribution on the risk of hydraulic fracturing in CO2 geological storage using an analytical
model of hydraulic fracturing in weak formations. The work is based on a Mohr–Coulomb dislocation
model that is extended to account for material with fracture toughness. The complete slip process that is
distributed around the crack tip is replaced by superdislocations that are placed in the effective centers.
The analytical model enables the identification of a dominant parameter, which defines the regimes of brittle
to ductile propagation and the limit at which a mode-1 fracture cannot advance. We examine also how the
corrosive effect of CO2 on rock strength may affect hydraulic fracture propagation. We found that a
hydraulically induced vertical fracture from CO2 injection is more likely to propagate horizontally than
vertically, remaining contained in the storage zone. The horizontal fracture propagation will have a positive
effect on the injectivity and storage capacity of the formation. The containment in the vertical direction will
mitigate the risk of fracturing and migration of CO2 to upper layers and back to the atmosphere. Although
the corrosive effect of CO2 is expected to decrease the rock toughness and the resistance to fracturing, the
overall decrease of rock strength promotes ductile behavior with the energy dissipated in plastic deformation
and hence mitigates the mode-1 fracture propagation.

Category

Academic article

Language

English

Author(s)

Affiliation

  • SINTEF Industry / Applied Geoscience
  • Aristotle University of Thessaloniki
  • Imperial College London
  • University of Cyprus

Year

2016

Published in

International journal for numerical and analytical methods in geomechanics (Print)

ISSN

0363-9061

Volume

40

Page(s)

1472 - 1484

View this publication at Norwegian Research Information Repository