(1) Rock Fracture Project, Stanford University, Stanford, CA
(2) Department of petroleum Engineering, Stanford, CA
Abstract: Fault Zone Permeability Upscaling: From Field to Numerical Modeling
We will present a permeability upscaling methodology using quantitative analog data from a faulted sandstone. Structure of faults resulting from slip along pre-existing joint zones and permeability of each feature of the fault zone determined from various techniques are incorporated in a numerical procedure used to upscale the permeability tensor of blocks comprising parts of the fault zone. In order to determine their upscaled permeability properties, the large blocks are discretized in smaller grid blocks. At small slip magnitude, cross-plots of upscaled permeability calculated for each grid block indicate that fault-parallel permeability is strongly increased compared to the host rock and that fault normal permeability is noticeably reduced. At large slip magnitude, although increased slip leads to higher density of shear-induced joints, fault-parallel permeability is not necessarily increased and fault normal permeability does not systematically decrease, which is related to the variability in the orientation of joints. Results of upscaling give a principal permeability direction between mean joint trend and mean fault strike for faults with a small amount of slip. For larger slip values, the principal permeability direction approaches the mean fault strike. The validation of this upscaling methodology through in situ infiltration tests will be discussed.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana