Shale formations have been widely characterized in recent years due to their importance in different petroleum and civil engineering applications, especially unconvential shale gas recovery. Hydraulic fracturing in these reservoirs requires having a complete understanding of the petrophysical, static-dynamic, ductile, and anisotropic properties of the shale. Creep deformation of these formations affects the state of regional stresses (impacts the success of hydraulic fracturing) and the transport properties of shale rocks (important in the long term). This paper presents preliminary results from an experimental program that explores ductile behavior of specimens of the Marcellus Shale formation from Allenwood, Pennsylvania through a series of hydrostatic and triaxial experiments. Experiments were performed at 20 and 30 MPa following the same deviatoric stress (DS) path. The results show that the magnitude of creep is directly proportional to the deviatoric stress level and the confining stress does not significantly affect the creep response.
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