EarthVision 7.5 Cellular Gridding

ev_cellg

The EarthVision^® Cellular Gridding module converts an EarthVision structure or property model into a cellular-grid format compatible for input to reservoir upscaling and simulation programs. Using an algorithm optimized for faults, the EarthVision Cellular Gridding program calculates cellular reservoir grids that accurately portray the structure and⁄or property in the original 3D model. The cellular 3D grid then provides the framework for calculating and predicting the flow of fluids within the reservoir. Unlike an EarthVision 3D grid, which has all of its grid lines parallel and orthogonal (thereby usually crossing structural and property features), a cellular grid is created so that its grid lines align to the major structural components of the model such as the faults and horizons.

In addition to the non-orthogonal nature of a cellular 3D grid, the property within each grid cell is cell centered. The grid cells need not have rectangular sides; nor must they be the same size throughout the cellular grid. (In EarthVision 3D grids, the grid cells must all be the same size in X and Y; the sides of the grid cells must be either squares or rectangles; and the property is node-centered, i.e., it is defined at each corner point of the cell.) The method used for creating EarthVision cellular grids decreases the loss of information between the structural-modeling and reservoir-simulation processes; thus the geocellular grids appropriately reflect the modeled geologic features.

An EarthVision cellular 3D grid file can be interactively displayed and examined in EarthVision′s Cellular Viewer; when creating the cellular grid, the general trend of the three major planes can be set interactively against the 3D EarthVision geologic model, also using the Cellular Viewer. Defining the planes while visualizing the 3D model allows for a more accurate representation of the model in the cellular grid. Once the results are satisfactory, the cellular grid can be exported to different simulator input formats such as Eclipse™, VIP CORP™, CMG™, FGRID Eclipse™, GRIDGENR™, and⁄or RESCUE™ format, then passed on for simulation.

Specifications

converts an EarthVision faulted structure or property model into a cellular grid format compatible for input to reservoir upscaling and simulation programs
industry-quality upscaling available
algorithm optimized for faults; may be used with a faulted or unfaulted model
cellular grid planes (i, j, and k) need not be orthogonal; however, orthogonality of the initial volume is easily maintained and the final grid is deformed appropriately to fit the structural model
spacing between i, j, and k planes can vary throughout the cellular grid
grid planes can be aligned to the major structural components of the model such as the faults and horizons
properties are cell centered; property value remains constant within a given grid cell
grid nodes can be split so that a single node can be on opposite sides of a fault
i-plane, j-plane, and k-planes can be user-entered via a table or interactively set in 3D using the Cellular Viewer
cellular grid resolution and cell size are user-controlled
variably spaced cellular grids (similar to a tartan pattern) are supported and are defined graphically
local grid refinement is supported and is specified graphically
local grids can be specified within other local grids
each local grid can have a unique variable spacing and refinement
output cellular grids can be limited to a smaller region of interest than that of the input model
output cellular grids can cover a larger volume than the geologic model
output grids are quality-checked and adjusted for negative, small, and wedge-shaped cells
antithetic, λ (lambda-shaped), and reverse faults are supported
individual faults can be specified as having the cells along an i plane, j plane, or ij plane aligned conformal to the fault, or the cells can be specified to ″stair step″ along the fault
at least one fault must align with the i, j, or ij plane to establish the grid orientation
faults can be verticalized to an existing grid line
output k layers are mapped to the geologic layers in the structural model
k layers can be conformal to any top, bottom, or both horizon surfaces, to neither, or to any external 2D grid surface, and can also be specified via thicknesses
rows and⁄or columns of cellular grid cells can be trimmed when creating the cellular 3D grid
cellular grid can be cut by a polygon in a ″cookie cutter″ fashion
cellular grids can be interactively displayed and examined in EarthVision′s Cellular Viewer
cellular grid can be exported to different simulator input formats (see Output Data)
grid reports can be calculated that include the cellular grid resolution, projection information, units, range, k layer attributes, and cell attributes
parameter files allow the GUI information to be saved and reused quickly and easily

Input Data

sequence file and associated files (2D and 3D surfaces, property data file(s), etc.) depicting the input geologic model
2D grid(s) to which the cellular grid space can be conformed (optional)
structural surfaces (as defined in a sequence file by the appropriate 2D grids) as the top and⁄or bottom conformal surface(s) to which the cellular grid k layers can be conformed (optional)
polygon file to laterally clip the cellular grid (optional)

Output Data

project file containing all the cellular gridding parameters
specification files containing parameters regarding the model area, geometry, and geology
cellular 3D grid depicting fault blocks, zones, and⁄or properties of the input model
Eclipse format grid (GRDECL)
VIP CORP format grid
CMG format grid (INC)
FGRID Eclipse format grid
GRIDGENR Text Format (GTF) grid
RESCUE format grid

User Interface

Graphical user interface
Interface can be bypassed by running the underlying computations from a script file Online Help⁄Documentation Features
Online help is available from the graphical user interface, and manual pages at the system prompt
Complete user documentation

This Module is an Option to

2D Surface and 3D Property Modeling System
Geologic Modeling System
Petroleum Suite
Environmental Suite

The Cellular Gridding module is not included in any other EarthVision module licenses. A site must have an ev_cellg (or ev_cellg_win or ev_cellg_net) license in order to run the Cellular Gridding module. For more information on this system or for hardware and third party software requirements, please contact your Dynamic Graphics representative.