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GTMORA: A GIS Toolset for Geometric and Topological Analysis of Sandbody and Fracture Networks From Modern and Outcrop Reservoir Analogs

Abstract

In subsurface reservoirs, the geometry and topology of sandbodies and fracture networks are key controls on fluid flow migration. As spatial extent and resolution of subsurface data such as seismic, core and wells are limited, modern depositional environments and outcrops are routinely used as analogs to understand and predict these features in the subsurface. While studies of modern and outcrop analogs are becoming increasingly quantitative with new remote sensing acquisition techniques, the extraction of geometric and topologic information remains typically a manual. Here we present GIS toolsets for the automated characterization of geometry and topology for both sandbody and fracture network analysis by demonstrating the algorithms on 3 modern and outcrop analogs. The GTMORA toolset help to define the geometry, shape and adjacency of interpreted modern sandbodies by automatically analyzing length, width, adjacency and centerline deviation. A 520 km2 mixed-influenced Mitchell River Delta, Australia, is used to demonstrate the connectivity of net reservoir elements (beach ridges and channels) and its implications for the subsurface. Similar geometric parameters from 2.5D interpretations of a fluvial Beckwith Plateau outcrop in Utah are used to define shape along strike, dip and planform profiles to create a stochastic object-based model. The new model creates channels that are 45% less volumetric to standard reservoir modeling workflows highlighting the importance of an accurate shape representation. Finally, the toolbox provides sampling, geometric and topological algorithms for the analysis of mapped 2D fracture networks from modern and outcrop analogs. The automated algorithms extracts geometric and topological attributes of the network to quantify and spatially map key network properties, such as intensity or connections per branch, allowing us to quantitatively characterize and assess clustering and connectivity. Applied to a strike-slip fault network offshore Hartland Point, north Devon, UK, the toolkit is used to illustrate its application in the characterization of the network and in assessing its connectivity. We believe that these tools provide a comprehensive analysis of digitized modern and outcrop data that will lead to new research into the quantitative assessment of connectivity for fluid flow. The implementation of such toolsets will vastly improve our efficiency when analyzing analog datasets for the subsurface.