The brittleness index in hydraulic fracturing
File(s)ARMA 15-489.pdf (277.72 KB)
Accepted version
Author(s)
Papanastsiou, P
Atkinson, C
Type
Conference Paper
Abstract
We present a new definition of a brittleness index which is used as a criterion for candidate selection of rock
intervals for hydraulic fracturing. The new index is a combination of material strength parameters and insitu stresses. It was derived
from an analytical model of hydraulic fracturing in weak formations of varying ductility. The model is based on Mohr-Coulomb
dislocations that are placed in the effective centres of the complete slip process that is distributed around the crack tip. The new
brittleness index varies between 0 and 1 with the one limit to correspond to brittle propagation and the other limit to a fracture that
requires infinite energy release per unit advance. The values between 0 and 1 correspond to fracture propagation of increasing
ductility from brittle to small scale and finally to large scale yielding. The results are particularly interesting for predicting the
propagation of axial fractures in the horizontal direction and their confinement in the vertical direction.
intervals for hydraulic fracturing. The new index is a combination of material strength parameters and insitu stresses. It was derived
from an analytical model of hydraulic fracturing in weak formations of varying ductility. The model is based on Mohr-Coulomb
dislocations that are placed in the effective centres of the complete slip process that is distributed around the crack tip. The new
brittleness index varies between 0 and 1 with the one limit to correspond to brittle propagation and the other limit to a fracture that
requires infinite energy release per unit advance. The values between 0 and 1 correspond to fracture propagation of increasing
ductility from brittle to small scale and finally to large scale yielding. The results are particularly interesting for predicting the
propagation of axial fractures in the horizontal direction and their confinement in the vertical direction.
Date Issued
2015-07-01
Date Acceptance
2015-05-08
Citation
ARMA 15, 2015
Publisher
ARMA
Journal / Book Title
ARMA 15
Copyright Statement
Copyright 2015 ARMA, American Rock Mechanics Association. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of ARMA
is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 200 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgement of where and by whom the paper was presented.
is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 200 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgement of where and by whom the paper was presented.
Source
49th US Rock Mechanics / Geomechanics Symposium
Publication Status
Published
Start Date
2015-06-28
Finish Date
2015-07-01
Coverage Spatial
San Francisco, California, USA