The ring structure of Siljan, located in the central part of Sweden, is considered by many researchers to be a meteorite (impact) crater. Impact craters are among the most complex geological objects on the Earth. The origin and formation of these structures still raises many questions. To find answers to these questions we need reliable geological information about the structure of the crater and the composition of the rocks. Information about the thickness and geological structure of the Siljan Ring area sedimentary cover will help to understand the process of the Siljan Ring structure’s formation as well as other similar geological formations on the Earth. Here, we present the results of laboratory studies of sedimentary rock samples taken from four exploration wells drilled in the vicinity of the Siljan Ring crater, which made it possible to compile their detailed lithological description. The laboratory studies included a structural analysis of the samples, and a texture and mineralogical analysis in thin sections. A structure analysis was carried out visually, while structural and mineralogical analyses were carried out on thin sections using a polarizing microscope and a scanning electron microscope. The main components of the rocks (minerals and fragments), along with their ratio and secondary transformations, were determined. The results of the structural analysis of the samples, and the textural and mineralogical analysis of the rocks in thin sections, showed that the sediments’ composition in the sedimentary cover near the Siljan Ring structure changes in different areas in accordance with their facies and stratigraphic characteristics. Furthermore, a change in the thickness of the sections and the succession sequences of rock units was established. A change of this nature is presumably caused by tectonic disturbances of an endogenous or impact source.

An explicit approach using symplectic time integration in conjunction with traditional finite difference spatial derivatives to solve the wave equation in moving media is presented. A simple operator split of this second order wave equation into two coupled first order equations is performed, allowing these split equations to be solved symplectically. Orders of symplectic time integration ranging from first to fourth along with orders of spatial derivatives ranging from second to sixth are explored. The case of cylindrical acoustic spreading in air under a constant velocity in a 2D square structured domain is considered. The variation of the computed time-of-flight, frequency, and wave length are studied with varying grid resolution and the deviations from the analytical solutions are determined. It was found that symplectic time integration interferes with finite difference spatial derivatives higher than second order causing unexpected results. This is actually beneficial for unstructured finite volume tools like OpenFOAM where second order spatial operators are the state-of-the art. Cylindrical acoustic spreading is simulated on an unstructured 2D triangle mesh showing that symplectic time integration is not limited to the spatial discretization paradigm and overcomes the numerical diffusion arising with the in-built numerical methods which hinder wave propagation. 

The reserves of hydrocarbons trapped in gas hydrate deposits are estimated to be enormous, especially comparing with the proven geological resources of natural gas. At the same time the origin of gas hydrate deposits is still debatable. Comparison of the component composition of hydrocarbon mixtures obtained as a result of abiogenic synthesis in the laboratory under thermobaric parameters similar to the conditions of the Earth’s mantle with the composition of samples of natural gas hydrates shows their similarity. This confirms our suggestion about the possible contribution of deep hydrocarbons in gas hydrate formation. Gas hydrate deposits could be formed as a result of upward vertical migration of deep hydrocarbon fluids along faults and fractures.

The article provides information on the main methods of the extraction of synthetic (kerogen) oil from oil shale and evaluates the results of the industrial implementation of these methods outside the Russian Federation. According to the US Geological Survey the geological resources of kerogen oil reach 390 billion tons (not including Russia). Oil shale processing methods are divided into ex-situ and in-situ. The main method of producing synthetic oil is the method of ex-situ retorting, while annual production volumes do not exceed 2 million tons. Currently, there are only nine active commercial projects dealing with synthetic oil production: three in Estonia and six in China. Another five projects have pilot status. None of the pilot projects related to application of in-situ methods of the synthetic oil production has entered the commercial phase. All five pilot projects based on in-situ methods in the last two decades have been closed or stopped. Major oil companies such as Shell, Chevron, ExxonMobil withdrew from all projects related to the processing of oil shale due to the high energy intensity of the processes and possible serious environmental problems. The processing of oil shale has a significant negative impact on the environment, primarily associated with groundwater and air pollution. The data presented in the article suggests that it is too early to claim a breakthrough in the development of kerogen oil.

The results of investigation of the phase behavior of a crude oil sample from the Kalchinsk oilfield at pressure up to 1.43 GPa in the temperature range of 140-336 K are presented. It is shown that crystallization occurs in the sample with increasing pressure (decreasing temperature) in a wide range of thermobaric parameters, after which the glass transition process is observed. Based on the experimental data, a phase diagram for the studied sample was constructed.

The concentration of carbon dioxide and methane in the atmosphere has significantly increased over the last 60 years. One of the factors in the growth of methane and its homologue emissions is the intense thawing of gas hydrates, mainly from the Arctic shelf, which remains one of the less studied sources of atmospheric hydrocarbon emissions. Oxidation of methane and light-saturated hydrocarbons by ozone in the upper part of the atmosphere leads to the formation of CO2. The analysis of several datasets presented in this paper allows us to find the correlation between CH4 and CO2 concentrations in the atmosphere. This finding suggests that methane and its homologues released from gas hydrates mainly in the Arctic shelf zone become a significant source of carbon dioxide in the atmosphere. Because the amount of hydrocarbons located in gas hydrate deposits on the Arctic shelf is huge, further evolution of this process can become a serious challenge.

The results of the measurement of the thermal conductivity and the relative volume of two crude oil samples at pressures up to 1 GPa are presented. It is shown that the dependence of thermal conductivity on pressure is a linear function, depends on isothermal compressibility of the liquid, and always increases with rise of pressure.

The heat capacity per unit volume rho c(p) of four crude oil samples were measured at pressure up to 1 GPa and ambient temperature using the transient hot-wire method. It is shown that with rise of pressure the rho c(p) of the investigated samples increases linearly with an average value of 0.051 MJ/(m(3)center dot K) for each 0.1 GPa. The same growth rate of rho c(p) was observed for all the investigated samples.

Research subject. The possible influence of the SiO2 environment as the most common component of the mantle on the deep abiogenic synthesis of hydrocarbons in the CaCO3–FeO–H2O and Fe3C–H2O systems under thermobaric conditions corresponding to those in the upper mantle is investigated. Materials and methods. Experiments were carried out using a high-pressure unit in Toroid-type chambers across the thermobaric range of 2.0–4.0 GPa and 220–750°C. CaCO3 and Fe3C were used as carbon donors, H2O was used as a hydrogen donor, and SiO2 was used as an environment. The synthesized products were analyzed by gas chromatography and X-ray diffraction. Results. Across the entire temperature and pressure range used, mixtures of light alkanes with the predominance of methane were obtained. The composition of the hydrocarbon systems synthesized in the presence of SiO2 was similar to that obtained at the same thermobaric parameters without SiO2, depending exclusively on the temperature and pressure of synthesis. The conducted X-ray diffraction analysis of solid products demonstrated transformation of quartz into coesite at 400°C and 750°C. Conclusions. According to the conducted investigation, the qualitative and quantitative composition of hydrocarbon systems formed during the abiogenic synthesis of hydrocarbons in the presence of SiO2 corresponds to the results of similar experiments without SiO2. However, the total yield of the hydrocarbon systems in the SiO2 environment decreases. The dependence of the composition of the synthesized hydrocarbon systems on the thermobaric conditions of synthesis remains in the SiO2 environment.

BiScO3 compound was obtained in the form of dense ceramic with a perovskite-type structure, and its complex characterization was determined for the first time. The corresponding synthesis procedure is described in detail. It is demonstrated that the temperature region of the phase stability at atmospheric pressure lies at T < 700 degrees C (973 K). It is shown that the crystal structure of the BiScO3 ceramic is centrosymmetric. Dielectric measurements of the synthesized sample performed at frequencies 25 Hz to 1 MHz and at temperatures 10-340 K show no changes typical for phase transition. Room-temperature infrared (30-15600 cm(-1)) and Raman (90-2000 cm(-1)) spectra of the prepared BiScO3 ceramic are measured, and information on the parameters of phonon resonances is obtained. The number of infrared modes exceeds that predicted by the factor group analysis of the noncentrosymmetric space group C2. The reason for selection rules violation can be associated with the disorder of the crystal structure and local distortions induced by the lone pair of electrons of Bi3+.