Premium
Formation stability after hydraulic fracturing
Author(s) -
Papanastasiou Panos
Publication year - 1999
Publication title -
international journal for numerical and analytical methods in geomechanics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.419
H-Index - 91
eISSN - 1096-9853
pISSN - 0363-9061
DOI - 10.1002/(sici)1096-9853(19991225)23:15<1927::aid-nag41>3.0.co;2-u
Subject(s) - hydraulic fracturing , stress (linguistics) , plane stress , fracture (geology) , deformation (meteorology) , geotechnical engineering , closure (psychology) , consistency (knowledge bases) , materials science , crack closure , yield (engineering) , geology , fracture mechanics , structural engineering , composite material , finite element method , engineering , mathematics , geometry , philosophy , linguistics , economics , market economy
This paper investigates stress changes resulting from fracturing in a weak formation and estimates the reduced risk of formation failure. The analysis is based on fracture propagation and closure of a plane strain elasto–plastic fracture. It is shown that during fracture propagation the area near the fracture tip undergoes plastic deformation, with the result that the in situ stresses there are significantly reduced from the original compressive state. The stress relief is driven by the reduction of the minimum in situ stress and the consistency condition which requires the stress state to remain on the yield or failure envelope. After fracture closure, due to permanent deformation the stress state does not return to its original state, as in the case of elastic material. The risk of formation failure, which is quantified with the introduction of a yield factor, is significantly reduced after fracturing and closure. The residual width from plastic deformation results in a non‐uniform closure stress on proppant with higher values near the tip and lower value near the wellbore which is detrimental to the stability of proppant. The closure stress becomes more uniform with increasing fracture length. Copyright © 1999 John Wiley & Sons, Ltd.