Determining factors of the unconsolidated rocks of Cenomanian reservoir on the Bolshekhetskaya depression

The relevance of the article is associated with the importance of the object of the research. Dozens of unique and giant oil and gas fields, such as Urengoyskoye, Medvezhye, Yamburgskoye, Vyngapurovskoye, Messoyakhskoye, Nakhodkinskoye, Russkoye, have been identified within the Cenomanian complex. The main feature of Cenomanian rocks is their slow rock cementation. This leads to significant difficulties in core sampling and the following studies of it; that is the direct and most informative source of data on the composition and properties of rocks that create a geological section.The identification of the factors, which determine the slow rock cementation of reservoir rocks, allows establishing a certain order in sampling and laboratory core studies. Consequently, reliable data on the reservoir and estimation of hydrocarbon reserves both of discovered and exploited fields and newly discovered fields that are being developed on the territory of the Gydan peninsula and the Bolshekhetskaya depression will be obtained. This study is also important for the exploration and development of hydrocarbon resources of the continental shelf in the waters of the Arctic seas of Russia as one of the most promising areas.As a result of the analysis, it was found that the formation of rocks of the PK1-3 Cenomanian age of the Bolshekhetskaya depression happened under conditions of normal compaction of terrigenous sedimentary rocks that are located in the West Siberian basin. Slow rock cementation of reservoir rocks is associated with relatively low thermobaric conditions of their occurrence, as well as the low content of clay and absence of carbonate cements. Their lithological and petrophysical characteristics are close to the analogous Cenomanian deposits of the northern fields of Western Siberia and can be applied to other unconsolidated rocks studied areas.

Study of synthesis of hydrogen and hydrocarbons by mechanochemical activation of the surface of mineral rocks

In the light of the eternal discussion regarding the sources of hydrocarbons for the initial oil and gas-forming substance, it is possible to recognize the legitimacy of both organic matter, which is confirmed by the biogenic theory of the origin of oil, and deep gases, declared by supporters of the theory of the inorganic concept, referring to the extraordinary richness of hydrocarbons in the mantle. But, the catagenic stage, the process of obtaining oil from the initial substance, in which the primary carbonaceous substance (often under such hypothetical concepts as “micron-oil”, “fluids”) passes into hydrocarbons in the form of oil deposits, causes no less scientific interest and also insufficiently studied. The author sees it as fair to attempt to put emphasis on predominantly geodynamic conditions, tectonic stresses, physico-chemical and thermobaric conditions, the generation of hydrocarbons, on the basis of the synthesis of hydrocarbons in any geological period. The article proposes the author’s chemical model describing the low-temperature polycondensation synthesis of hydrocarbons from water and carbon dioxide in the process of mechanical reactions on the surface of a rock model.

Prediction of the phase state of hydrocarbon deposits in traps of a combined structure

The possibilities of predicting the phase state of hydrocarbon deposits by geochemical methods are considered. The article briefly describes the well-known gas-geochemical and petrochemical forecasting methods, and also proposes to use trace element indicators of fluids for these purposes. Based on the study of the distribution of the trace element composition of oils and condensates in Western Siberia, Turkmenistan, the Caspian Sea region, New Zealand and some other regions, the trace element geochemical indicators of naphthides are recommended for diagnostics of oil and gas condensate systems. The fact of the presence of trace elements in the light fractions of hydrocarbon fluids and the revealed genetic differences between oils and condensates make it possible to use trace element characterization of fluids for practical problems of oil and gas prospecting geology. Since by now hydrocarbon production reserves in anticlinal structures is nearing exhaustion, considerable attention is paid to complex combined traps confined to greater depths and severe thermobaric conditions.

Deep hydrocarbon cycle

Research subject. Experimental modelling of the transformation of complex hydrocarbon systems under extreme thermobaric conditions was carried out. The results obtained were compared with geological observations in the Urals, Kamchatka and other regions.Material and methods. The materials for the research were a model hydrocarbon system similar in composition to natural gas condensate and a system consisting of a mixture of saturated hydrocarbons and various iron-containing minerals enriched in 57Fe. Two types of high-pressure equipment were used: a diamond anvils cell and a Toroid-type high-pressure chamber. The experiments were carried out at pressures up to 8.8 GPa in the temperature range 593–1600 K.Results. According to the obtained results, hydrocarbon systems submerged in a subduction slab can maintain their stability down to a depth of 50 km. Upon further immersion, during contact of the hydrocarbon fluid with the surrounding iron-bearing minerals, iron hydrides and carbides are formed. When iron carbides react with water under the thermobaric conditions of the asthenosphere, a water-hydrocarbon fluid is formed. Geological observations, such as methane finds in olivines from ultramafic rocks unaffected by serpentinization, the presence of polycyclic aromatic and heavy saturated hydrocarbons in ophiolite allochthons and ultramafic rocks squeezed out from the paleo-subduction zone of the Urals, are in good agreement with the experimental data.Conclusion. The obtained experimental results and presented geological observations made it possible to propose a concept of deep hydrocarbon cycle. Upon the contact of hydrocarbon systems immersed in a subduction slab with iron-bearing minerals, iron hydrides and carbides are formed. Iron carbides carried in the asthenosphere by convective flows can react with hydrogen contained in the hydroxyl group of some minerals or with water present in the asthenosphere and form a water-hydrocarbon fluid. The mantle fluid can migrate along deep faults into the Earth’s crust and form multilayer oil and gas deposits in rocks of any lithological composition, genesis and age. In addition to iron carbide coming from the subduction slab, the asthenosphere contains other carbon donors. These donors can serve as a source of deep hydrocarbons, also participating in the deep hydrocarbon cycle, being an additional recharge of the total upward flow of a water-hydrocarbon fluid. The described deep hydrocarbon cycle appears to be part of a more general deep carbon cycle.

New «green» inhibitors of gas hydrate formation for the oil and gas industry based on polysaccharides

The thermobaric conditions for the formation of gas hydrates in the presence of the sodium salt of carboxymethylcellulose, dextran, and arabinogalactan were studied in a quasi-equilibrium thermodynamic experiment. It is established that polysaccharides slow down the rate and change the conditions of gas hydrate formation of a mixture of natural gases, showing the properties of a thermodynamic and kinetic inhibitor with technological efficiency exceeding methanol by 170-270 times when used in the same dosages. The results of the development of a «green» synergistic inhibitor of gas hydrate formation «Glycan RU» on their basis are presented, which includes a combination of thermodynamic and kinetic inhibitors. Pilot field tests of «Glycan RU» were carried out at the wells of the Priobskoye, Prirazlomnoye, Ombinsky, Zapadno-Ugutskoye oilfields. It was found that at dosages of 1000 g/m3 and 500 g/m3, there is no formation of hydrate plugs in the annulus. «Glycan RU» is recommended for industrial use by the technology of periodic injection and/or continuous dosing through wellhead dispensers. Keywords: carboxymethylcellulose; dextran; arabinogalactan; polysaccharides; «green» inhibitor of gas hydrate formation; «Glycan RU».

The Role of Iron Carbide in the Abyssal Formation of Hydrocarbons in the Upper Mantle

The existence of iron carbide in the upper mantle allows an assumption to be made about its possible involvement in the abyssal abiogenic synthesis of hydrocarbons as a carbon donor. Interacting with hydrogen donors of the mantle, iron carbide can form hydrocarbon fluid. In order to investigate the role of iron carbide in the abiogenic synthesis of hydrocarbons, the chemical reaction between cementite Fe3C and water was modeled under thermobaric conditions, corresponding to the upper mantle. A series of experiments were conducted using a high-pressure high-temperature Toroid-type large reactive volume unit with further analysis by means of gas chromatography. The results demonstrated the formation of hydrocarbon fluid in a wide range of thermobaric conditions (873–1223 K, 2.5–6.0 GPa) corresponding to the upper mantle. A strong correlation between the composition of the fluid and the pT conditions of the synthesis was illustrated in the investigation. The higher temperature of the synthesis resulted in the formation of a “poor” hydrocarbon mixture, primarily comprising methane, while a higher pressure yielded the opposite effect, converting iron carbide into a complex hydrocarbon system, containing normal and iso-alkanes up to C7 and benzene. This correlation explains the diversity of hydrocarbon systems produced experimentally, thus expanding the thermobaric range of the possible existence of complex hydrocarbon systems in the upper mantle. The results support the suggestion that the carbide—water reaction can be a source of both the carbon and hydrogen required for the abyssal abiogenic synthesis of hydrocarbons.

CARBON-LIKE UNITS FOR A NANOSIZED TOOL BASED ON THE USE OF BORON NITRIDE AND DIAMOND

Phase transformations of pyrolytic boron nitride were studied under thermobaric conditions, providing direct transformation of a hexagonal structure into a cubic one. If only the martensitic mechanism of the cooperative rearrangement of atoms is realized, diamond-like aggregates with an equiaxed highly dispersed structure and submicron grain sizes are formed. The presence of a solvent-catalyst (RC) in the system leads to an increase in the particle size of the cubic phase due to recrystallization by the diffusion mechanism, and the high catalytic activity of RC causes the appearance of zones of directional crystal growth in the synthesized samples.