ESTIMATION OF SATURATION OF PRODUCTIVE SEDIMENTARY RESERVOIRS OF THE WEST SIBERIAN FIELD WITH LOW RESISTIVITY VALUES

Abstract

The main problem that is discussed in this article is related to the interpretation and analysis of low-resistivity productive reservoirs of the Vasyugan formation of one field in Western Siberia. A feature of the reservoirs of the Vasyugan formation is the underestimated values of the oil saturation coefficient. In this case, certain difficulties arise when determining the nature of saturation and justifying the position of fluid contacts in the formation.The work carried out a detailed analysis of the measurements results of physical properties on core samples, refined the petrophysical model and boundary values of parameters for interpreting this type of reservoirs of the Vasyugan formation. As a result of the research, the authors identified the most likely reasons for the underestimation of electrical resistivity values in productive reservoirs, which should be explained by the structure and fractional composition of rocks and the presence of pyrite. The authors propose a refined methodology with justification for new cutoff values of electrical resistivity and the use of a capillary model, which increases the reliability of the well logging data analysis on assessing the nature of saturation in low-resistivity productive formations and the depth of oil-water contacts.Certain recommendations are gave in the article for further research of the unconventional type of the Vasyugan formation, which include the coring and core analysis like granulometric, X-ray diffraction, studies of the mineral composition of clays and use of VIKIZ and multi-probe lateral logging and nuclear magnetic logging.According to the authors, this will increase the reliability of assessing the lithological composition of reservoir rocks and reservoir properties in lowresistivity oil-saturated reservoirs.