Evaluating of core saturation in case of oil source rocks of the Bazhenov formation by standard methods is not trivial task that hinders systematic measurements. An example is the existing method of distilling water in the Zaks (or Dean-Stark) apparatus, which does not allow to determine small amounts of water with high accuracy, in addition, the method is not "in-line" - it takes up to a week for one measurement. This leads to use for reserve calculation and planning mining values of oil saturation, which are not confirmed by actual data or determined on single core samples. The method was offered authors, based on combination of thermal and spectrometric techniques, let allowed measuring water saturation and oil saturation for core 12 oil fields. The results obtained indicate about significant variation in saturation by cross section of the Bazhenov formation, and the modal values of water saturation exceed those, that are usually used for reserve calculation. «Scale» factor significantly influences on the core properties, and actual values of water saturation may be higher. The degree of mobility of water in open porous space is important value. Established opinion that all water in the Bazhenov formation is associated with clays minerals is not confirmed by specially conducted researches. The dependence of water content and clayiness is linear with a high dispersion. The lowest values of water content tend to highly siliceous and carbonate rock, and the water in open voids is rather capillary-bound. The obtained values of chemically bound water released in process decomposition of minerals and transformation organic matter during heating, indicate high water content in closed pores. Studying of the features of water release in the temperature range corresponding to the decomposition (pyrolysis) of organic matter and minerals showed the presence of a large amount of water in closed pores.
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