Kinematic Dilation During the Hydraulic Stimulation of Pre-fractured Rocks. Issue 3 (9th May 2019)

• Record Type: Journal Article
• Authors: Roshankhah, S.; Cruz, L. G.; Shin, H.; Lizcano, A.; Santamarina, J. C.
• Is Part Of: Géotechnique letters. Volume 9:Issue 3(2019)
• Page Start: 1
• Page End: 28
• Publication Date: 2019-05-09
• Subjects: Rocks/Rock mechanics -- Monitoring -- Laboratory tests -- Numerical modeling; Geotechnical engineering -- Periodicals; Engineering geology -- Periodicals; 624.151
• DOI: 10.1680/jgele.18.00173
• Languages: English
• ISSNs: 2045-2543

Abstract

Abstract : A single planar fracture geometry dominates the process of hydraulic fracturing in homogeneous, isotropic, and cohesive materials. However, this fracture geometry cannot explain the high recovery efficiency observed in shale gas and enhanced geothermal energy. Experimental and numerical studies reported here demonstrate that pre-fractured, structured reservoirs experience extensive geometric distortion and dilation around the main opening-mode discontinuity generated upon high pressure fluid injection. This kinematic dilation may decrease at high confining stresses because blocks deform and split. Parameters such as the dominant fracture set orientation, block size and slenderness, and blocks overlap length characterize a pre-structured medium and determine its deformation pattern and hydromechanical behavior. Kinematically-controlled dilational distortion greatly improves fluid conductivity in the pre-structured medium. A six-power relationship is anticipated between the enhanced hydraulic conductivity and the roundness of the main opening.