Print this pageAdvanced Geostatistical Reservoir Characterization
McNAIR, KIMAKA N. and AVIANCE DYKE
Advanced geostatistical reservoir characterization is a DOE funded collaborative research project between Fort Valley State University and Applied Research Associates, Inc. This project uses geostatistical tools to enhance reservoir characterization accomplished by conventional methods.
The King field, a well characterized oil field in Southeast Illinois, was characterized conventionally by use of Stratamodel, a geological modeling software package. Data from this field was imported into ISATIS, a geostatistical software package, where geostatistical analysis was done.
Geostatistics entails several steps to produce a model. The first step is
simple statistics, the second is using variograms to establish the 
spatial
relationship present in the data set, the third is using the established spatial
relationship to krige on a grid, and the last step is to determine the
accuracy/error of the kriged results.
Omni-directional variograms were calculated initially; however since the
dimensions in the X- and Y-directions are each roughly 10,000 ft whereas, the
dimension in the Z- direction is only 100 ft, no spatial
correlation appeared in
the omni- directional variograms. Thus, directional variograms were calculated
in the vertical, N-S, and E-W directions. The directional variograms suggested a
large-scale trend present in the data which corresponds to non-stationary data.
Ordinary kriging requires that the data set be stationary; thus a model was fitted to the variogram and the kriging neighborhood parameters were set to capture only the stationary portion of the variogram. The kriged results are what were used to compare the conventional and geostatistical models.