The most topical and challenging issues related to study of heavy oil reserves are discussed. The scope of the project includes laboratory studies, core macro description, reserves estimate parameters based on geophysical survey results. The aim of the project is to update geological structure and to estimate reserves of the Sheshminskian formation with increased focus on potential determination of porosity and oil saturation using well logging data. To determine the porosity factor, data on neutron gamma logging, compensated neutron logging, and density logging were used. Corrections for compensated neutron logging results were used, including corrections for borehole effect and effect of shaliness. Also, reproducibility of porosity factors determined by well logging and laboratory-based core studies was analyzed. The most reliable methods to determine reserves estimate parameters were identified. Particular attention is given to selection of reference beds to calculate correction for shaliness. The authors address the issues related to calculation of formation volume factor for two reservoir types, clay and non-clay; the procedure to convert weight to volume oil saturation estimates is described. Well logging data can also be used to locate gas accumulations in target intervals. The above methods and procedures make it possible to understand how permeability and porosity change in area and in thickness, and to assess the extent of rock saturation with heavy oil providing, thus, a reliable estimate of reserves and an efficient reservoir management program.
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