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Propagation of Hydraulically Induced Fractures--a Continuum Damage Mechanics Approach

Peter Valkó
Organization: Texas A&M University
Department: Harold Vance Department of Petroleum Engineering
URL: http://www.pe.tamu.edu/valko/public_html/
M. Economides
Journal / Anthology

International Journal of Rock Mechanics, Mining Science and Geomechanics Abstracts
Year: 1994
Volume: 31
Issue: 3
Page range: 221-229

The propagation of fluid-driven fractures during massive hydraulic fracturing treatments of hydrocarbon bearing formations is modelled using a continuum damage mechanics approach. The rationale for such an approach is that when only linear elastic fracture mechanics concepts are used certain inconsistencies are encountered such as difficult-to-explain treating pressures that are continuously increasing with time and are abnormally high. In this work, an expression for the fracture propagation rate is derived from Kachanov's law of damage accumulation. The derived expression is used as a boundary condition in a Perkins-Kern-Nordgren type model (assuming constant height) and in one of its extensions (allowing for height migration). It is explained how the rupture process can retard the fracture propagation rate leading to much higher treating pressures than predicted from the original "fluid flow constrained" boundary condition. The continuum damage mechanics based model is applied to published examples manifesting abnormally high pressures. It is demonstrated how the parameters of the model can be identified from standard fracturing tests.

*Engineering > Mechanical and Structural Engineering