SAGE2001 FEATURES

SAGE2001 is a Windows 95/98/NT/2000/XP software toolkit designed for:

  • the calculation of directional sample variograms and,
  • the modeling of sample variograms.

SAGE2001 is designed to work with many directional sample variograms at one time. Experience shows that at least 20 to 30 directional sample variograms are required to obtain a reasonably representative model of 3 dimensional spatial continuity. SAGE2001 enables the user to easily calculate 1 to 50 or more directional sample variograms in one run and then fit a model to all of the directional sample variograms simultaneously by regression.

Sample Variogram Calculation Features:

  • Either two or three-dimensional data may be processed. There is no limit on the size of the input data file.
  • The selection of data points may be restricted to user specified limits on each coordinate (x,y,z) and/or to user specified limits on the variogram variable itself.
  • The selection of data may also be restricted by specifying a correlated variable within user specified limits.
  • The selection of data may also be restricted to specific rock types, alteration types, soil types, etc.
  • The input data may be transformed using the log or indicator transform.
  • Down-the-hole variograms can be calculated.
  • Directional sample variograms can be fully defined by user specified azimuths, dip angles, tolerance angles, vertical bands, horizontal bands, lag distances, and lag tolerances
  • Both omni-directional and omni-directional-horizontal (all directions are parallel to a plane, possibly dipping) may be calculated.
  • Sample variogram estimators include the traditional average squared difference estimator; the correlogram; and the pairwise relative estimators.
  • Smaller subsets of the input data may be selected randomly from large data files.
  • Excellent report files and summary statistics are easily generated and viewed on screen or printed for future reference.
  • Sample variograms can easily be viewed on screen, one at a time, or by displaying multiple directions on one screen. Hardcopy of all graphic displays can be easily sent to the printer or clipboard.

Sample Variogram Modeling Features:

In addition to calculating directional sample variograms, SAGE2001 can also fit a variogram model to the directional sample variograms by least squares or regression. For example, given 37 or more directional sample variograms, SAGE2001 can rapidly calculate the set of variogram model parameters that minimize the average squared difference between the variogram model and all 37 directional sample variograms simultaneously. The variogram model parameters calculated by SAGE2001 include the following:

    • C0 -- the nugget
    • C1 - the coefficient of the first nested structure.
    • RX -- the range of the first structure in the direction of the rotated X axis.
    • RY -- the range of the first structure in the direction of the rotated Y axis.
    • RZ -- the range of the first structure in the direction of the rotated Z axis.
    • AZ -- the rotation angle of the first structure around the Z axis.
    • AX -- the rotation angle of first structure around the rotated X axis.
    • AY -- the rotation angle of the first structure around the rotated Y axis.
    • C2 - the coefficient of the second nested structure.
    • RX -- the range of the second structure in the direction of the rotated X axis.
    • RY -- the range of the second structure in the direction of the rotated Y axis.
    • RZ -- the range of the second structure in the direction of the rotated Z axis.
    • AZ -- the rotation angle of the second structure around the Z axis.
    • AX -- the rotation angle of the second structure around the rotated X axis.
    • AY -- the rotation angle of the second structure around the rotated Y axis.
  • Note that the rotation angles for the second structure are generally very different from those of the first structure. Thus, the maximum number of unique variogram model parameters determined by SAGE2001 is 15.
  • Any subset of these parameters may be specified by the user in which case SAGE2001 will calculate values for the remaining parameters not specified by the user (if they exist). Thus, SAGE2001 provides the user with a broad range of control over the modeling process from full user control to that where SAGE2001 does all the work.
  • The sample variogram(s) may originate from one, two, or three-dimensional data.
  • The variogram model may consist of one or two nested structures.
  • Each structure may be a spherical or exponential model.
  • A minimum number of pairs/sample variogram point may be specified.
  • The maximum lag distance may be specified.
  • Each sample variogram point may be weighted by the number of pairs.
  • Each directional sample variogram may be weighted by the inverse number of sample variogram points per direction.
  • The user may select one of several popular conventions for the anisotropy rotation angles or define his own rotation conventions. Thus, the variogram models developed by SAGE2001 are compatible with and may be used with any geostatistical software package. For example, SAGE2001 supports the following popular software packages:
    • GSLIB
    • The Medsystem
    • Vulcan
    • DataMine
    • Gemcom
    • User Defined Conventions

The models of spatial continuity provided by SAGE2001 are generally more accurate than those obtained using any other software package. This is because 30, 40, or 50 directional sample variograms provide a far better sample of spatial continuity than the 3 or 4 directions typically calculated and modeled by other software. Only SAGE2001 is capable of modeling 30, 40, 50, or more sample variograms simultaneously.