EarthVision 7.5 Geostatistics
ev_gs
The EarthVision® Geostatistics module provides 2D and 3D statistical methods for computing grid nodes based on 2D or 3D data. Geostatistics provides a way to add knowledge about the geology of a petroleum reservoir, aquifer, etc. to the modeling process that may not be reflected in the input data. Extensive pre-gridding data analysis capabilities help the EarthVision user optimize variogram model preparation prior to the kriging calculation. Variance grids can be calculated simultaneously with the estimate grid.
Specifications
The geostatistics model is integrated with the advanced structure models calculated using the EarthVision Geologic Structure Builder. For example, geostatistical models can be calculated conformal or nonconformal to structure, in selected zones and selected fault blocks.
- The following kriging algorithms are included: †
- simple kriging
- ordinary kriging
- non-stationary kriging
- kriging with external drift
- kriging with a trend (universal kriging)
- collocated cokriging
† Point or block kriging can be used with each of these algorithms.
- Various tools are provided to allow examination of the statistics prior to modeling:
- sample count (number)
- minimum and maximum value
- first and third quartiles
- mean
- median
- variance
- standard deviation
- scatterplots
- quantile graphs
- histograms
- probability plots
- p-p and q-q plots
- declustering tools
- The spatial relationships of the data to be kriged can be analyzed using the following variograms and variogram maps:
- traditional semivariogram
- covariance
- correlogram
- general relative
- pairwise relative
- logarithmic
- rodogram
- madogram
- h-scatterplots can also be generated for points within the variograms types listed above.
- A graphical variogram model viewer is included that helps to visualize and analyze the variogram model fit to the input 2D and 3D data.
- An unlimited number of structures can be used to model the variogram when fitting a curve, giving greater control in modeling complex spatial correlations.
- The following functions can be used in each structure:
- power
- gaussian
- spherical
- exponential
- A search radius for values to be used in a node estimate can be specified.
- The minimum/maximum number of neighboring values included in the grid node calculation can be defined.
- Visual tools for parameter analysis are included:
- search pilots graphically display the search limits specified along with the 2D or 3D data being used
- lag pilots graphically display the lag divisions along with the 2D or 3D data being used
Input Data
- tab-, comma-, or white-space-delimited free-format and fixed-format 2D and 3D ASCII scattered data
Output Data
- EarthVision 2D estimate and variance grids
- EarthVision 3D estimate and variance grids
- cross validation files
- variogram data files
- variogram model files
Other Information
Program Limits
ev_gs:
- 2,000,000 input data points
- 1024 x 1024 maximum 2D grid size
- 10,000,000 3D grid nodes
Limits when part of ev_env: †
- 50,000 input data points
- 512 x 512 maximum 2D grid size
- 500,000 3D grid nodes
† A limited version of Geostatistics is shipped with the Environmental Suite license.
User Interface
- graphical interface
- interface can be bypassed by running the underlying computations from a script file
Online Help and Documentation
- 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 Modeling System
- 3D Property Modeling System
- 2D Surface and 3D Property Modeling System
- Geologic Modeling System
- Petroleum Suite
- Environmental Suite †
† Ordinary kriging, variography, histogram, and quantile graph capabilities from this module are included in the Environmental Suite. The remainder of capabilities are available as an extra-cost option.
For more information on these systems or for hardware and third party software requirements, please contact your Dynamic Graphics representative.
