An Integration of Fault Rock Properties Through Time with Basin Modeling

Marek Kacewicz¹, Russell K. Davies², and Rob Knipe^3
1Chevron Energy Technology Company, Sugar Land, TX
²Rock Deformation Research, McKinney, TX
³Rock Deformation Research Ltd, University of Leeds, Leeds, United Kingdom

Charge in structurally complex systems requires a good understanding of structural and diagenetic evolution of the basin. Typical structural restorations utilized in basin models provide a basic geometric description of faults bounding tectonic blocks. They neither address dynamically changing block boundaries nor provide any information about pressure communication across the blocks due to fault rock properties. A dynamic aspect of the boundaries is due to tectonic reactivation of bounding faults, changing effective stress and thermal conditions and properties along the faults such as clay smear, diagenetic alteration of fault rocks and cataclasis.

Quality of pressure and hydrocarbon charge predictions using basin modeling approaches requires a good understanding of spatial and temporal behavior of matrix and fault rock properties. The flow properties of the faults can be estimated from a database of hundreds of measurements that are upscaled to the faults of interest by assuming a simple clastic stratigraphic classification that includes clean sandstones with low clay contents, impure sands with moderate clay contents and shales with high clay contents. These measurements also show the dependence of flow properties with geohistory including maximum depth of burial and uplift. Models calibrated to the fault rock measurements have been developed that estimate the cross flow and along flow properties of the faults depending on whether the behavior is and expected dilation or contraction in the fault. The modeled properties directly affect hydrocarbon migration directions.

This paper presents an integrated approach based on diagenetic and mechanical predictions of fault and matrix rock properties combined with basin modeling. Presented case studies demonstrate how the approach helped to reduce charge related uncertainty.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas