Sealing assessment of normal faults in clastic reservoirs: The role of fault geometry and shale smear parameters

We report on a PC software (FAULTAP) developed for sealing assessment of normal faults in clastic reservoirs. Fault surface is constructed from seismic data, and subsurface lithology is projected onto the fault surface using well log data and seismic horizons. Structural data of the fault (such as throw, heave, dip angle, and strike) are calculated and visualized. Shale smear has been recognized as a major mechanism of across-fault sealing in sandstone-shale successions. Five algorithms for evaluation of shale smear have been programmed in the software. Shale Smear Factor and Smear Gouge Ratio pertain to the total fault offset, while Clay Smear Potential, Shale Gouge Ratio and Clay Content Ratio pertain to selected points along the fault offset. The output data of these modules can be displayed on the fault surface, Allan-type juxtaposition diagrams, and cross plots.