HR: 0800h
AN: H11B-0297    [Abstracts]
TI: Dynamic Micro-CT Study of Fracture-Matrix Flow During Capillary Imbibition in Layered Berea Sandstone
AU: * Karpyn, Z T
EM: ztk101@psu.edu
AF: Energy Institute and Department of Energy and Geo-Environmental Engineering, The Pennsylvania State University, University Park, PA 16802 United States
AU: Halleck, P M
EM: pmh2@psu.edu
AF: Energy Institute and Department of Energy and Geo-Environmental Engineering, The Pennsylvania State University, University Park, PA 16802 United States
AU: Grader, A S
EM: grader@pnge.psu.edu
AF: Energy Institute and Department of Energy and Geo-Environmental Engineering, The Pennsylvania State University, University Park, PA 16802 United States
AU: Elsworth, D
EM: elsworth@psu.edu
AF: Energy Institute and Department of Energy and Geo-Environmental Engineering, The Pennsylvania State University, University Park, PA 16802 United States
AB: Studies concerning flow in fractured rocks have important applications in hydrocarbon recovery, hydrogeology, and environmental remediation of subsurface spills, such as DNAPLs. To properly design immiscible flow processes in those systems, it is crucial to understand fracture-matrix transfer mechanisms. The goal of this work is to provide a mechanistic description of capillary-driven imbibition in fractured media and the effects of fluid occupancy in the fracture and of matrix heterogeneity on saturation distribution. Capillary imbibition experiments where performed in a layered Berea sample, 4.75 cm long and 2.54 cm in diameter, with a single longitudinal fracture. The artificially created fracture was oriented perpendicular to the natural bedding of the rock. The sample was initially vacuum saturated with non-wetting phase. Small amounts of a wetting phase were introduced into the bottom of the fracture, allowing it to imbibe and exchange places with the resident non-wetting phase through the fracture-matrix interface. Progress of the imbibition process was monitored after each injection using high-resolution Micro Computed Tomography (CT). Micro-CT also provided non-destructive means to characterize the fracture structure and rock properties. A series of simulation scenarios were also tested using a commercially available package developed by the Computer Modeling Group (CMG). Experimental observations combined with simulation results indicate that the fracture itself exhibits a strong capillary behavior. Its rough-walled nature, leads to a two-phase flow similar to that in porous media. Experimental observations also show a strong correspondence between fluid invasion in the matrix and variations in porosity in the rock's bedding planes. Our results suggest that different porosities correspond to different permeabilities and capillary pressure curves. Fluid accessibility in the fracture space is also an important factor governing imbibition in fractured media. Fluid discontinuity and occupancy are key parameters affecting fluid accessibility between matrix and fracture space. Other factors affecting imbibition are interfacial tension, fracture roughness, and presence of micro-fractures.
DE: 5104 Fracture and flow
DE: 5139 Transport properties
DE: 3947 Surfaces and interfaces
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting