engleski

Estimating subsurface lithology distribution of a theoretical model by geomathematical methods

One of the key elements during regional geological subsurface explorations is a valid estimate of lithology distribution. Lithological properties of the rocksin the area between wells is conventionally estimated based on well data using either conventional deterministic approach or by stochastic algorithms. Because the uncertainty, spatial and time variability cannot be avoided in geology, the aim of this research is to determine theoretical lithological composition of rocks in the area between wells, as realistically as possible. Variogram, as a starting point, is a basic term of geomathematical analysis which presents random field structure and it can only depend on the distance between measured points and on the difference in value between them (Andričević et al., 2006). Indicator kriging is used as a main method for estimation the spatial distribution of the lithological composition. It builds the cumulative distribution function at each point, based on the behavior and correlation structure of indicator transformed data points in the neighborhood (Isaaks and Srivastava, 1989). Theoretical model which represents fluvial facies with five different lithologies was made in Petrel E&P software platform. The aim was to achieve "the most accurate" model that best shows real relations of facies to the original theoretical model, by using mentioned geomathematical tools as an introduction to the processes which will be performed on actual well data.

: Lithological composition, variogram, indicator kriging, subsurface explorations

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