3D Geological Modeling Features for U1 Horizon in the West Part of Vasugan Formation Spread

The main oil-bearing horizon of vasuganskaya formation – U1 – nowadays seems to be the main support for oil production during decline of production from Cretaceous sandbeds in Western Siberia. The main geological features of the horizon are high vertical and lateral heterogeneity, facies changeability and abnormal oil and water distribution. There are some extra features in the west part of vasuganskaya formation sread zone, which are results of regional vasuganskaya (mostly sand and silt) formation change for abalakskaya clay formation. One of them is undersaturation. New version of 3D geological modeling methodology is offered. It is based on simultaneous accounting of sedimentologic (facies) model, seismic facies and inversion results, petrophysical analysis of pore distribution (for different lithotypes and facies) and oil saturation from pore and structural elements relation. The keystone of the methodology is facies maps and vertiacal proportion curves convolution, complicated with seismic validity data. The result of the methodology is 3D stochastic model which can be used for detail reserves estimation (including uncertainty analysis and dividing reserves for different facies and lithotypes ), upscaling and dynamic modeling and well trajectory planning.