Home – Home – Jornals – Russian Geology and Geophysics 2005 number 2

Increasingly more attention is paid to the problem of hydrocarbon production from reservoirs with a complex geologic structure. In particular, these beds can be of lenticular structure, with separate sandstone lenses distributed in a shale matrix. A stochastic approach seems to be quite natural to describe such deposits.The probabilistic description of a system of lenses involves such parameters as: shape and size of deposit, shape and size of lens, probability density of distribution of lenses, and number of lenses in the study area.Mathematical tools have been devised to describe relationships between a system of lenses and a system of wells. Formulas for the probabilities of the relevant events have been derived and used for solving an inverse problem. The parameters of the system of lenses are numerically estimated by the method of maximum likelihood using data of exploratory drilling.Some results of practical significance have been obtained. The proposed approach has been used to analyze the uncertainty and risk of well location and to estimate the effectiveness of horizontal well drilling and hydraulic fracturing in lenticular reservoirs. The described approach is illustrated by its application to the estimation of oil field parameters. An example was a field in West Siberia.