Half-Graben-Scale Geocellular Outcrop Modelling of Rift Initiation Strata from Lidar-Based Digital Outcrop Data: The Nukhul Syncline, Suez Rift, Egypt
Paul Wilson, David Hodgetts, Franklin Rarity, Rob L. Gawthorpe, Ian R. Sharp, 2011. "Half-Graben-Scale Geocellular Outcrop Modelling of Rift Initiation Strata from Lidar-Based Digital Outcrop Data: The Nukhul Syncline, Suez Rift, Egypt", Outcrops Revitalized: Tools, Techniques and Applications, Ole J. Martinsen, Andrew J. Pulham, Peter D.W. Haughton, Morgan D. Sullivan
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The Nukhul Formation (Suez rift) consists of fluvial and tidally influenced shallow marine strata that were deposited in fault-controlled seaways and tidal embayments during rift initiation. In this study, we create a half-graben-scale, high-resolution (typical grid cell dimensions 20 m x 20 m x <1 m), geocellular outcrop model of the Nukhul Formation. The evolution of the normal fault system in the study area is associated with the development of fault-parallel and fault-perpendicular folds. The changing nature of the structural template, and the resulting geomorphology, during deposition led to complex syn-rift stratigraphic architecture and facies distributions. We use a LIDAR-based digital outcrop approach to map this geological complexity to a high degree of accuracy, for export to reservoir modelling software. Software developed in-house was used to integrate field observations with the digital dataset, aid interpretation, and create realistic surface meshes from outcrop data. Facies modelling used a combination of sequential indicator simulation and object-based modelling approaches. Sedimentary logs were attached to the dataset and used as conditioning data. 2D probability maps, source points, and flow lines constrained the geocellular outcrop model to match the known geology. The approach leads to improvements in three areas: (i) geological knowledge of the study area, (ii) data portability, and (iii) geocellular outcrop modelling. Comparison between the final geocellular outcrop model, outcrop geology, and inferred palaeogeography shows that the geology of the Nukhul Formation is realistically modelled. The final reservoir model can be used as an analogue for similar geological settings. It can be applied to improve the prediction of subsurface geology in analogous reservoirs and to increase the accuracy of static connectivity and flow simulations. Ultimately this will improve knowledge of the impact of facies heterogeneities on reservoir performance and lead to increased efficiency of reservoir drainage.