ABSTRACT:

Shear dilation was identified as the dominated mechanism which enhanced the permeability of unconventional reservoir by the mean of hydraulic fracturing. However, the relevant research for the role of shear dilation in hydraulic fracturing are mainly based on theoretical studies and numerical simulation but rarely experimental investigation. We conducted scaled hydraulic fracturing tests on 10cm ductile and brittle samples under true tri-axial stress condition. We monitored the wellbore pressure during the fracturing tests. Furthermore, we also conducted CT scanning on the tested samples. Both wellbore pressure and pressurization diagnostic and 3D projection from CT scanning were interpreted. We experimentally validate the theory of “high pressure drop near the fracture tip due to shear dilation”. We found that for both longitudinal and transverse hydraulic fracture, the shear dilation was more significant and the propagation path are more tortuous in ductile rock rather than that of brittle rock. The insight may provide better understanding of shear dilation for both modeling and hydraulic fracturing treatment design in field.

Keywords:
reservoir geomechanics, fracturing materials, wellbore integrity, hydraulic fracturing, complex reservoir, Fluid Dynamics, flow in porous media, proppant, Upstream Oil & Gas, coalbed methane
Subjects:
Wellbore Design, Hydraulic Fracturing, Reservoir Characterization, Reservoir Fluid Dynamics, Unconventional and Complex Reservoirs, Wellbore integrity, Fracturing materials (fluids, proppant), Reservoir geomechanics, Flow in porous media, Coal seam gas
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2019. American Rock Mechanics Association
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