A knowledge database of hanging-wall traps that are dependent on fault-rock seal
Published:July 17, 2020
Peter G. Bretan, Graham Yielding, Einar Sverdrup, 2020. "A knowledge database of hanging-wall traps that are dependent on fault-rock seal", Integrated Fault Seal Analysis, S. R. Ogilvie, S. J. Dee, R. W. Wilson, W. R. Bailey
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Hanging-wall traps are successful trapping styles with discoveries made in many sedimentary basins worldwide. Examples of hanging-wall traps are documented in the literature but very few describe the role played by fault-rock seal on trap integrity. This contribution focuses on hanging-wall traps that are dependent on fault-rock seal. Analysis of 18 examples of hanging-wall traps has revealed that the hydrocarbon column height trapped by fault-rock seal is typically less than 190 m. Cross-plots of shale gouge ratio (SGR) and buoyancy pressure from hanging-wall traps have a similar data distribution to published SGR–buoyancy pressure calibration plots. The similarity in data distribution indicates a similarity in the overall fault-sealing mechanism: namely, the capillary fault sealing through the incorporation of clay/shale material into the fault zone. Published ‘global’ calibration plots of SGR v. buoyancy pressure can be used to evaluate the sealing or non-sealing risk of hanging-wall traps in the same manner as for footwall traps.
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Integrated Fault Seal Analysis
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Faults commonly trap fluids such as hydrocarbons and water and therefore are of economic significance. During hydrocarbon field development, smaller faults can provide baffles and/or conduits to flow. There are relatively simple, well established workflows to carry out a fault seal analysis for siliciclastic rocks based primarily on clay content. There are, however, outstanding challenges related to other rock types, to calibrating fault seal models (with static and dynamic data) and to handling uncertainty.
The variety of studies presented here demonstrate the types of data required and workflows followed in today's environment in order to understand the uncertainties, risks and upsides associated with fault-related fluid flow. These studies span all parts of the hydrocarbon value chain from exploration to production but are also of relevance for other industries such as radioactive waste and CO2 containment.