Home – Home – Jornals – Russian Geology and Geophysics 2018 number Неопубликованное

A multilayer approach to resistivity well log inversion has been developed to estimate the true formation resistivity of oil and gas reservoirs in cases where the application of conventional layer-by-layer interpretation techniques is difficult or impossible. Provided the available initial data are sufficient, the approach enables the assessment of formation properties under conditions of significant vertical heterogeneity. However, an increase in the number of parameters of the geoelectrical model inevitably leads to increased equivalence of the inversion results. This paper proposes an approach to improving the stability of multilayer inversion in presence of strong parameter equivalence. The approach is based on a solution regularization mechanism and a method for incorporating a priori petrophysical information. The proposed regularization mechanism allows for the selection of a model characterized by the most gradual vertical variation of reservoir resistivity from a variety of equivalent solutions. The mechanism does not impose constraints on the surrounding non-reservoir formations, which ensures its applicability to high-contrast geological sections. The method for incorporating a priori petrophysical information allows the equivalent solutions space to be narrowed by restricting the admissible ranges of variation of the geoelectrical model parameters based on petrophysical data. The results of numerical experiments using resistivity well logs typical for terrigenous formations in Western Siberia demonstrate the effectiveness of the proposed approach under conditions of both significant vertical heterogeneity and high reservoir clay content.