The article presents the results of a stochastic inversion in one of the licensed areas of the Samara region. Stochastic inversion due to the involvement of borehole data has a better resolution than deterministic inversion; however, more data needs to be set for calculations - one-dimensional vertical trend of reservoirs, calculation of probability density functions of selected lithotypes and variograms, creation of a multilevel hierarchical model of lithotypes. At the initial stage the quality of seismic and borehole data is monitored by stratigraphic well tie, calculation of correlation coefficients and the study of the relationships of lithotypes with elastic parameters, which confirmed the possibility of stochastic inversion. The target object of the study was the carbonate layer of the Mendym horizon in the interval of Upper Devonian deposits. The complexity of performing stochastic inversion was due to the small thickness of the target object (less than 12 m), as well as, to the uncertainty in identifying lithotypes based on the results of logging interpretation for the range of boundary values of impedance and porosity. More than 100 realizations were calculated, of which 50 were selected according to the criterion of similarity of model impedancecs with impedances in wells. The obtained implementations allowed us to obtain the lithotypes probabilities and porosity. Based on the results of the work performed for the target horizon, maps of effective thicknesses and porosity of reservoirs were obtained with satisfactory convergence with well data.
References
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