Anyone who has done exploration or reservoir studies involving large numbers of logs, cores, or seismic data is aware of the great amount of manual labor required to reduce the data, to draw structure and thickness contour maps, and to make lithologic cross sections. While computers are commonly used to draw contour maps, lithologic cross sections and three-dimensional interpretations are still made by hand.

Computer programs have been developed that build and use 3-D models. These programs use data from wells to interpolate geologic properties in three dimensions between control points much as a geologist constructs cross sections, that is, by correlating between stratigraphic horizons. Modeling may be done at any scale, from large basins to individual reservoirs, and with an appropriate amount of detail. After the model is constructed it is available for calculations and displays. Cross sections and facies maps can be constructed to show the geographic extent of rock properties. Information in the model can also be used to construct contour maps, such as net pay thickness or average porosity, and to compute volumes.

Such modeling should not be done as if using a "black box." Geological interpretation must also be taken into consideration. Complete geological analyses include such factors as the data type, methods of stratigraphic correlation, calculation methods, trends, and types of boundaries between geologic units.

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