--> Abstract: Modeling and Prediction of Localized Flow in Fractured Rock Masses, by D. J. Sanderson and X. Zhang; #90942 (1997).

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Abstract: Modeling and prediction of localized flow in fractured rock masses

SANDERSON, DAVID J. and XING ZHANG

The localization of fluid flow is of fundamental importance to many aspects of reservoir engineering as well as in groundwater flow in fractured rock. Numerical modeling of the coupled mechanical and hydraulic behavior of rock-masses, using distinct element methods (UDEC), demonstrates that a change in the stress state can result in a sudden transition from diffuse flow through fracture networks to highly localized flow generated by the opening up of `pipes' at fracture intersections. A series of results for selected fracture networks and loading configurations will be presented. The influence of the 1) fracture network geometry, (connectivity, fracture density, orientation, distribution, etc.) and 2) in situ stress on the critical phase boundary between diffuse (plate) and localized (pipe) flow will be investigated. The geological evidence for localization of flow in vein systems will also be examined.

Multifractal techniques have been used to characterize the resulting heterogeneity of the flow in order to generalize the results of the modeling of discrete systems to a more continuum-based description of the flow, obviating the need for complete characterization of the individual `pipes' within specific networks.

Engineering activity (drilling, fluid extraction, pressure change, etc.) will change the state of stress, at least locally, and thus effect the deformation and flow in fractures. The ability to predict if such changes are likely to lead to critical changes in the flow characteristics has widespread implications in all forms of subsurface engineering.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria