--> ABSTRACT: Faulting and Fluid Flow by Invasion Percolation in Three Dimensional Basin Models, by Stuart M. Clarke, Graham D. Williams, and John Howell; #90906(2001)

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Stuart M. Clarke1, Graham D. Williams1, John Howell2

(1) Keele University, Keele, United Kingdom
(2) Liverpool Univeristy, Liverpool, United Kingdom

ABSTRACT: Faulting and Fluid Flow by Invasion Percolation in Three Dimensional Basin Models

Faults are key controlling elements in fluid flow systems in sedimentary basins. When faults undergo displacement, they change their fluid transmissibility properties by juxtaposing varying lithologies across the fault, by pumping or valving diagenetic fluids, and by smearing semi-permeable or impermeable clays and shales within fault zones.

Three dimensional sequential modelling of fault displacement has enabled the building of earth models with time-varying structural geometries. Based on the geometries of strata that are cut by faults, their juxtaposition relationships and their physical properties, various cross fault relationships have been modeled in three dimensional space. Structural restoration, or retro-deformation provides 'snapshots' of fault and stratal geometries through time. These are used in forward modelling from the undeformed state of the rock volume to its present-day structural architecture. The evolution of cross fault relationships is dynamically calculated and forward modelling allows a prediction of the development of fault zone smears, gouges and cataclasis.

Cross fault juxtaposition of strata and fault zone processes such as smearing and cataclasis have been incorporated into three dimensional transmissibility models involving invasion percolation (IP). The effects fault zone processes on fluid flow are incorporated into four dimensional forward models which, through the IP algorithm, calculate hydrocarbon fluid flow pathways controlled by lithology (transmissibility distribution) and structural geometries in rock volumes. The controls of fluid flow by lithology distribution and variations in cross-fault sealing capacity have been modelled both spatially and with time in fieldwork-derived models of rock volumes from the Moab Fault and the Book Cliffs (Utah U.S.A.).

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado