What Geostatistical Modelling is and what it is not
Published:January 01, 1998
Geostatistics provides its user with a toolbox of approaches for generating realistic 3D representations of the distribution of heterogeneities.
The geostatistical method to use depends on the type of variable that is modelled, on the depositional environment and of the scale at which the representation must be used.
Geostatistics allows the generation of equiprobable “realisations” of the subsurface, all compatible with the data and the statistical parameters used as input to the models.
The variability between geostatistical realisations is a measure of the uncertainty remaining after constraining the realisations by the input data and the statistical parameters. This allows the quantification of non-uniqueness.
Geostatistics treats deterministic information as such: deterministic input is honoured by realisations. Geostatistics generates equiprobable representations of what cannot be represented deterministically.
Geostatistics is the “glue” holding the various subsurface disciplines together. It provides the means of integrating different kinds of data into the construction of 3D representations of heterogeneities.
Geostatistics is not an algorithm tossing a coin to decide which facies are present between wells.
Geostatistics is not a substitute to ignorance about the geology of a field.
Geostatistics is not a substitute to the geologist, the geophysicist or the reservoir engineer.
Geostatistics is not a push-button automatic approach.
Geostatistics is not an alternative to “deterministic approaches”. Geostatistics treats known information as deterministic, unknown information as probabilistic.
There is no such thing as an “absolute” or “objective” measure of uncertainty. Geostatistical variability is controlled by the chosen model and its parameters, which may be proved wrong as new data are acquired.
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Geostatistics In Petroleum Geology
This publication comes from a course designed to explain, in non-mathematical terms, that geostatistics is a simple and flexible formalism for quantifying geology. Topics included in the publication are a brief history of the development of eostatistical techniques in the oil industry, the use of geostatistics for multidisciplinary data integration, andthe use of geostatistics for quantification of undertainty.