14.7.3 Grids

• A description of the topology (indexing) and geometry of the grid representation.
• A grid, or a subrepresentation of a grid, may provide a representation of an interpretation of a RESQML geologic feature, most often an earth model or a structural organization.

• Properties may be attached to a grid representation, i.e., a grid supplies the topological support for properties.

RESQML also provides a closely related “grid connection set” representation, which is based on “cell-face-pairs”, for the purpose of describing the connections between grid cells, and a “blocked wellbore” representation to describe wellbore trajectories discretized on a grid.

Although it may seem reasonable to organize grids by the geometry of their cells, industry applications more naturally segregate grids by their topology, i.e., the dimensionality of the indexing of the cells. RESQML follows this approach and supports six distinct grid classes:

• Three grid classes are fundamental and will be recognizable to most practitioners.

• Three grid classes are combinations of these fundamental classes, and provide support for advanced variations in unstructured grids.

All grids support various extensions, such as higher order cell geometry, although some extensions may only exist for particular classes. For example, only IJK grids support radial grid cell interpolation. The corner point grid supported by many applications is a specific example of an IJK grid, although without all of the extensions now supported in RESQML

For more information, see the Grid chapter in the RESQML Technical Usage Guide.