f Computer interpretation of lateral resistivity logs

Reservoir rocks parameters evaluating in particular determination of effective porosity and water, oil or gas saturation is based on resistivity logs measured in boreholes. It is realised in stationary variants (classical resistivity logs and laterologs different types) and in variants using electromagnetic fields (induction and EPT). Measurement methods applied in recent decades in Poland and Middle or East European countries used for determining resistivity a set of five lateral devices of different length or a set of two normal devices and one lateral device, which allowed to examine the formation in radial direction. Thus there exists the huge archive of data which may be treated as a base for detailed quantitative interpretation. Obtaining real values of petrophysical parameters in particular hydrocarbon saturation depends on applying such interpretation methods, which allow to find a proper model of the formation and determine real resistivity of beds and zones changed by invasion of the mud and other processes in the formation after drilling a borehole.