Property modeling with 'simbox'

In JewelSuite Subsurface Modeling, the execution of facies and rock property modeling takes place on an orthogonal grid, the ‘simbox’. The 'simbox' represents the depositional space, without any geological structure, comparable to an EasyGrid. Input data for the modeling job, upscaled grid properties and supporting properties, are transferred to the 'simbox' before execution of the modeling and after the execution, the calculated results are transferred back onto the geological JewelGrid. This transfer is called ‘mapping’. So called ‘mapping rules’ define how data is transferred to and from the ‘simbox’. For cells on the geological grid which are not affected by a fault, the mapping rules are very simple: one cell on the geological grid corresponds to one cell on the 'simbox'. For cells, which are affected by a fault, the mapping rules become more sophisticated.

Mapping rules for affected cells close to a fault

Due to the nature of the JewelGrid, it can happen that multiple cells along a fault are linked to one single cell in the 'simbox'. To make the consequences transparent, JewelSuite Subsurface Modeling applies a manageable set of mapping rules for cells affected by a fault, when transferring data between the geological JewelGrid and the 'simbox':

From JewelGrid to 'simbox'

If cells are affected by a fault, it depends on the fault throw how values are transferred from the geological JewelGrid to the 'simbox'. For this purpose, JewelSuite Subsurface Modeling does not distinguish between normal and reverse faults.

• Small fault throw - offset is smaller than two times average layer thickness: values of multiple geological cells are merged to the corresponding 'simbox' cell. The mapped value is the volume weighted average of the cells with a common IJK index. The same rules apply for Upscaled Properties and Supporting Properties. Merging rules are based on the property’s upscaling template.
• Large fault throw - offset is larger or equal to two times average layer thickness: Of the cells with a common IJK index, only the values of affected cells in the hanging wall are mapped to the corresponding 'simbox' cell and used for modeling.

From 'simbox' back onto JewelGrid

When transferring modeled values from the 'simbox' back to the geological JewelGrid, for cells affected by faults this means the value of one simbox cell is mapped to corresponding JewelGrid cells. If the cell in the geological grid already holds an upscaled property, it will not be overwritten. Values of upscaled properties (hard data) is always honored. As a potential consequence, upscaled properties might appear alien to the surrounding cells once the modeled values are transferred.