Fracture-permeability behavior of shale. (September 2015)

• Record Type: Journal Article
• Authors: Carey, J. William; Lei, Zhou; Rougier, Esteban; Mori, Hiroko; Viswanathan, Hari
• Is Part Of: Journal of unconventional oil and gas resources. Volume 11(2015:Sep.)
• Page Start: 27
• Page End: 43
• Publication Date: 2015-09
• Subjects: Hydraulic fracturing -- Shale gas -- Caprock integrity -- Geomechanics -- CO2 sequestration; Secondary recovery of oil -- Periodicals; Shale gas -- Periodicals; Heavy oil -- Periodicals; Shale oils -- Periodicals; Energy development -- Periodicals; Petroleum -- Periodicals; Oil-shales -- Periodicals; Natural gas -- Periodicals; Coalbed methane -- Periodicals; Petroleum industry and trade -- Periodicals; 665.4
• DOI: 10.1016/j.juogr.2015.04.003
• Languages: English
• ISSNs: 2213-3976

Abstract

Graphical abstract: Highlights: Permeability across versus parallel bedding was 30 mD compared with 900 mD. Deformation of 0.4–1% was required to generate transmissive fractures. Fractures across bedding planes more complex and pervasive than when parallel. Fracture-permeability observations indicate importance of pre-existing fractures. Observed permeabilities (30–900 mD) much greater than previous experimental studies. Abstract: The fracture-permeability behavior of Utica shale, an important play for shale gas and oil, was investigated using a triaxial coreflood device and X-ray tomography in combination with finite-discrete element modeling (FDEM). Fractures were generated in both compression and in a direct-shear configuration that allowed permeability to be measured across the faces of cylindrical core. Shale with bedding planes perpendicular to direct-shear loading developed complex fracture networks and peak permeability of 30 mD that fell to 5 mD under hydrostatic conditions. Shale with bedding planes parallel to shear loading developed simple fractures with peak permeability as high as 900 mD. In addition to the large anisotropy in fracture permeability, the amount of deformation required to initiate fractures was greater for perpendicular layering (about 1% versus 0.4%), and in both cases activation of existing fractures are more likely sources of permeability in shale gas plays or damaged caprock in CO2 sequestration because of the significant deformation required to form new fracture networks. FDEM numerical simulations were able to replicate the main features of the fracturing processes while showing the importance of fluid penetration into fractures as well as layering in determining fracture patterns.