A hypothetical geomechanics model for the assessment of potential environmental impact of shale gas fracking – Part I: from ground water perspective

Baolin Wang

In the proceedings of: GeoMontréal 2013: 66th Canadian Geotechnical Conference; 11th joint with IAH-CNC

Session: Soil and Rock Mechanics V

ABSTRACT: A hypothetical geomechanics model is presented for the assessment of ground condition change in response to shale gas extraction in the Utica shale region, eastern Canada. It is based on the fact that hydraulic fracturing reduces the stiffness of the shale unit and alters the in-situ stress. If a large body of rock is fractured, stress would re-distribute itself in the overall rock structure. A discontinuum model was used for the analysis. The results confirmed the hypothesis. Based on the level of ground deformation obtained from this study and other reported data, the hydraulic conductivity of the caprock may experience an increase by one to two orders of magnitude. This may cause regional ground water flow regime change that should be further studied.

RÉSUMÉ: L™article présente l™utilisation d™un modèle géomécanique afin d™évaluer l™importance des modifications induites dans les formations géologiques par l™extraction de gaz dans les shales d™Utica de l™est du Canada. L™hypothèse de travail est basée sur le fait que la fracturation hydraulique réduit la rigidité des shales. Si un large volume de roche est fracturé, les contraintes vont se redistribuer dans l™ensemble de la structure géologique. Un modèle de milieu discontinu est utilisé pour l™analyse. Les résultats obtenus confirment l™hypothèse de départ. L™amplitude des déformations calculées lors de la modélisation, ainsi que les données de la littérature, indiquent que la roche de couverture peut être affectée par une augmentation de la conductivité hydraulique de un à deux ordres de grandeur. Ces déformations peuvent par conséquent provoquer une modification du régime d™écoulement des eaux souterraines, un phénomène qui nécessite d™être étudié plus en détail.

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Cite this article:
Baolin Wang (2013) A hypothetical geomechanics model for the assessment of potential environmental impact of shale gas fracking – Part I: from ground water perspective in GEO2013. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoMon2013Paper368,author = Baolin Wang,title = A hypothetical geomechanics model for the assessment of potential environmental impact of shale gas fracking – Part I: from ground water perspective,year = 2013}