Influence of pressurization rate on the magnitude of the breakdown pressure

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

34 Scopus citations

Abstract

A mathematical model is proposed to account for rate and size effects on the magnitude of the breakdown pressure during a hydraulic fracturing experiment. This model recognizes the existence of two lengthscales: A diffusion length 6 (a lengthscale representative of the distance of propagation of the pore pressure perturbation from the boundary) and a microstructural length A (which underpins the failure process). In this context, rate effects are seen as a consequence of the interaction of these two lengthscales. An expression for the breakdown pressure pt, which depends explicitly on the pressurization rate, is derived. It is demonstrated that the Haimson-Fairhurst (H-F) and the Hubbert-Willis (H-W) expression for the breakdown pressure correspond respectively to the asymptotically slow and fast pressurisation regimes. However, the H-F limit is shown to be the appropriate expression for "permeable" rocks, as hydraulic fracturing experiments in these rocks are practically always in the slow regime. It is also shown that in low permeability/low porosity rocks, rate effects are potentially significant and that both the H-F and the H-W expressions are acceptable limits, depending on the pressurization rate.

Original languageEnglish (US)
Title of host publicationRock Mechanics Proceedings of the 33rd U.S. Symposium
PublisherPubl by A.A. Balkema
Pages325-333
Number of pages9
ISBN (Print)9054100451
StatePublished - Jan 1 1992
Event33rd U.S. Symposium on Rock Mechanics, USRMS 1992 - Santa Fe, United States
Duration: Jun 3 1992Jun 5 1992

Publication series

NameU.S. Symposium on Rock Mechanics

Other

Other33rd U.S. Symposium on Rock Mechanics, USRMS 1992
Country/TerritoryUnited States
CitySanta Fe
Period6/3/926/5/92

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