BACK

• Evaluating the robustness of fault and horizon mapping should always be the first step in evaluating fault seal and other fault properties - if faults are not mapped as rigorously as they should be, seal or any other evaluation of them will not be meaningful. See our fault seal project example.
• ABAL can evaluate fault seal in terms of shale smear algorithms, e.g. SGR (shale gouge ratio), but we have our own proprietary seal evaluation technique. This incorporates an empirically derived, database approach to fault seal: from an extensive database of sealing and non sealing faults from the North Sea, the most important parameters with respect to fault seal were derived and formulated to provide a fault seal prediction algorithm. Like SGR, FSP (fault seal probability) evaluations have been tried and tested in several parts of the World.
• FSP values can be converted into fault plane permeabilities and mapped along fault planes. These calculations include an assessment of fault zone (core) thickness, which is based on our own databases of field-derived fault zone thickness measurements.
• But we have increasingly recognised that, especially in sand rich sequences, fault seal processes other than shale smear may be dominant. A key process is cataclastic deformation, and the development of granulation seams (see our damage zone and granulation seams page), both in and around faults. We have evaluated and quantified damage zones in the field, recreated and analysed them in the lab, and developed techniques for predicting their effect on permeability reduction.
• We use FaultRes, our new software tool, to calculate and display fault plane properties along fault planes. These include in addition to fault seal potetnial, fault rock type, damage zone thickness, granulation seam density and permeability reduction due to damage zone structure (see also reservoir modelling).