Rock Dilation and Its Effect on Fracture Transmissivity
(July 2018)DOI: doi.org/10.15530/URTEC-2018-2903018
Abstract
Dilation of rock describes the increase in joint aperture during shear; which opens up additional space in the joint and can change its transmissivity, which in turn changes the overall permeability of the rock mass. Source mechanisms computed from recorded microseismic events during hydraulic fracturing show a significant amount of shear failure during treatment. Therefore, the ability to properly account for shear-induced dilation is of considerable importance in assessing the transmissivity of fracture networks and hydrocarbon deliverability of stimulated reservoirs. In this study, 22 dilation responses from direct shear tests under constant normal loads were analyzed for their effect on fracture transmissivity. The cubic law amplifies the dilation effect on transmissivity, however, onset of this amplification is delayed compared to the onset of dilation, and the magnitude of the delayed response is related to surface roughness.