Suchergebnisse

The first results of determination of the content of different types of bound water by hygrometric method — adsorption isotherm method — for extracted rock samples of Bazhenov formation are presented. All obtained water sorption isotherms have a well-defined S-shape, which allows to determine the maximum possible amount of bound water of different types (mono -, poly-and capillary condensation) in all studied samples. The inflection points of the isotherms of the extracted samples fully correspond to the inflection points of the isotherms of the native samples. Based on the obtained results, it is possible to further estimate the specific surface area of the samples, and then determine the hydrophobicity coefficient and the parameters of the associated oil saturation.

The article presents the first results of determining the content of different types of bound water by hygrometric method — adsorption isotherm method — for non-extracted air-dry samples of Bazhenov formation rocks. The obtained water sorption isotherms for the studied samples have a well-expressed s-shape, which allows to determine the maximum possible amount of bound water of different types in them — mono-, poly — and capillary condensation and to draw an important conclusion about the hydrophilicity of the Bazhenov formation deposits. According to the form of sorption isotherms, the amount of bound water and the proximity of mineral compositions, nine samples were combined into 4 different groups, the remaining samples were considered individually. A correlation between the pore water content and the content of mono- and multilayer water was found.

The reservoir water content is one of the key parameters to following reliable hydrocarbon reserves estimation of low-permeable shale reservoirs with unconventional hydrocarbon reserves. The extensive review of applied direct and indirect laboratory methods for determining the water saturation in unconventional shale reservoirs is presented in this article. The essence, advantages, disadvantages and limitations of methods are described in detail. It was demonstrated that direct laboratory methods (retort method, Zaks, Dean–Stark) which were originally developed for traditional reservoir rocks, give results with an error of up to 50% for rocks samples of unconventional reservoirs. On the other hand the Evaporation Method specifically developed for low-permeable rocks takes less time and provides more accurate (error up to 6.8%) gravitational and bonded water determination moreover, it requires up to 5 times less rock material for analysis.

The paper provides experimental characterization of the ion-exchange capacity of low-permeable shale rocks of the Bazhenov Formation of the central and southern parts of the Nizhnevartovsk arch, Western Siberia. We found that the cation exchange capacity (3.30–17.01 meq/100g) and the specific surface area (10.05–12.66 m2/g) depend on the clay minerals content, but not on the kerogen. The paper describes type of the exchange complex of the studied Bazhenov Formation rock samples and discusses the possible reasons for the distribution of exchangeable cations. The cation exchange complex of most part of studied Bazhenov Formation samples has a marine type (rCa/(rNa+rK)<1).