Modelling hydraulic permeability evolution in fault damage zones

Geological faults are planar structures oriented in three-dimensional space on which shear displacement has occurred. Faults can be barriers to flow, conduits, or combinations of the two and their hydraulic properties vary considerably over both space and time. Current field and borehole data collection techniques are unable to predict their hydraulic behaviour and a high level of risk is attached to such assessments in the petroleum and waste disposal industries. This paper presents the first published research investigating the spatial and temporal evolution of fault permeability in the damage zone surrounding a fault using numerical modelling. The model (MOPEDZ) uses the finite element method to simulate the coupled physical and chemical processes inherent in permeability evolution, and generates a two dimensional description of the damage zone both in terms of its structural architecture and its constituent permeabilities. We present the theoretical and computational model so far alongside two preliminary applications.