A method for generating volumetric fault zone grids for pillar gridded reservoir models

Abstract

a b s t r a c tThe internal structure and petrophysical property distribution of fault zones are commonly exceedingly complex compared to the surrounding host rock from which they are derived. This in turn produces highly complex fluid flow patterns which affect petroleum migration and trapping as well as reservoir behavior during production and injection. Detailed rendering and forecasting of fluid flow inside fault zones require high-resolution, explicit models of fault zone structure and properties. A fundamental requirement for achieving this is the ability to create volumetric grids in which modeling of fault zone structures and properties can be performed. Answering this need, a method for generating volumetric fault zone grids which can be seamlessly integrated into existing standard reservoir modeling tools is presented. The algorithm has been tested on a wide range of fault configurations of varying complexity, providing flexible modeling grids which in turn can be populated with fault zone structures and properties.

Surface-Based Geological Reservoir Modelling Using Grid-Free NURBS Curves and Surfaces

“…A higher degree of geometrical accuracy, which captures intended facies proportions and connectivity, is achieved by using NURBS surfaces without having to increase model resolution. The advantage of using parametric surfaces such as NURBS to represent geological geometries in an accurate way can arguably be illustrated most clearly by considering common, but complex, structural configurations that are difficult or impossible to represent using conventional pillar grid approaches (Georgsen et al 2012;Gringarten et al 2008;Hoffman and Neave 2007;Holden et al 2003;Qu et al 2015). Figure 10 shows NURBS-surface-based models of three examples of such structural configurations.…”

Incorporation of deformation band fault damage zones in reservoir models

“…The latter is to include the damage zone and comprises all cells adjacent to and up to a predefined distance away from the fault plane ( Figure 3B). The generation of the fault zone grid is performed by an algorithm embedded in Havana, which allows the width and xyz resolution of the fault zone grid to be specified (Syversveen et al, 2006;Qu et al, 2015). In the present study, resolution of the fault zone grid is specified as 1 m (3.28 ft) in the fault-perpendicular (x) direction and 5 m (16.4 ft) in the fault-parallel (y) and the vertical (z) direction, yielding a total of 2.88 million cells.…”

“…Fault zone grids are subsequently populated with properties using conventional reservoir modeling tools and merged back into the full reservoir model. At present this is not part of any standard workflow used by the petroleum industry but a prototype method developed for research purposes (e.g., Fredman et al, 2007Fredman et al, , 2008Soleng et al, 2007;Fachri et al, 2011;Qu et al, 2015).…”

GO2OGS 1.0: a versatile workflow to integrate complex geological information with fault data into numerical simulation models

“…The workflows use external open-source meshing tools (e.g., GMSH, Geuzaine andRemacle, 2009 3 , or TetGen, Si, 2015 4 ), or an interface to the Ansys 5 modeling environment. Recently, Qu et al (2015) offered a method to generate volumetric gridded fault zones by adding elements in the respective areas to the existing grids. This method, although shown to be applicable on a multitude of setups, will require an existing base mesh of good quality, requires the use of additional software, and is not open-sourced.…”