Bituminous substances in soils of Baikal Rift zone

Parameters of hydrocarbon complex of the soils of lacustrine-alluvial plain and sandy uplands of the Baikal rift zone within the Barguzin Depression have been studied. Data were obtained on organic (non-carbonate) carbon, chloroform and hexane bitumoids, as well as on individual polycyclic aromatic hydrocarbons. The content, composition and properties of bitumoids vary depending on the intensity of endogenous activity. In soils located in the zone of active unload of hydrothermal waters and hydrocarbon fluids, atypical accumulation of organic carbon was noted; the concentrations of bitumoids do not correlate with its content. High values of the bitumoid coefficient, significant level of polycyclic aromatic compounds and their diversity, in combination with salts accumulation, indicate an additional influx of hydrocarbons and instability of the soil hydrocarbon system. The level of the indicators shifts towards background values in the soils of sandy hills with a complex combination of exogenous and endogenous factors of soil forming. Studied parameters of the soil hydrocarbon system in aggregate can serve as markers of the intensity of endogenous processes.

Monitoring the composition of gas condensate well streams based on samples taken from multiphase flow meters

The article highlights the relevance of reliable estimation of the composition and properties of reservoir gas during the development of gas condensate fields and the complexity of the task for reservoirs containing zones of varying condensate content. The authors have developed a methodology that allows monitoring the composition of gas condensate well streams of similar reservoirs. There are successful examples of the approach applied in Achimov gas condensate reservoirs at the Urengoy oil and gas condensate field. The proposed approach is based on the use of the so-called fluid factors, which are calculated on the basis of the known component compositions of various flows of the studied hydrocarbon system. The correlation between certain "fluid factors" and the properties of reservoir gas (usually determined by more labor-consuming methods) allows one to quickly obtain important information necessary to solve various development control tasks.

Triassic Hydrocarbon System of the Middle-Caspian Oil and Gas Basin

The objective of this paper is to assess the generation potential of the Triassic hydrocarbon (HC) source rocks for the petroleum potential of the Middle-Caspian Oil and Gas Basin. Tectonically the study area belongs to the Epigercine Scythian-Turanian plate, which includes the following major tectonic elements: the Karpinsk-Mangyshlak ridge and the Prikum-Central Caspian system of troughs and uplifts. Comprehensive research approach to identify the main features of the Triassic hydrocarbon system, such as the interpretation of seismic data, laboratory geochemical analysis and evolution restoration of the hydrocarbon systems elements by 3D basin modeling techniques. The geochemical research includes pyrolytic analysis of potential Triassic source rocks, determination of the vitrinite reflectance values, chromatography-Mass Spectrometry studies of molecular structure. The subsequent basin modeling made it possible to integrate a wide range of geological and geophysical information into a single complex. These basin modeling results provide a better understanding of evolution restoration of the hydrocarbon systems elements and make it possible to foresee hydrocarbon accumulation's localization. The combined set of research helped to identify the boundaries of the Triassic HC source rocks in the Middle-Caspian Basin. It also allowed characterizing in detail their geochemical parameters and evaluating the volume of its generation potential. Triassic deposits are part of the taphrogenic intermediate complex of the Scythian platform and mainly located in graben structures. The increased content of organic matter is associated with the Lower Triassic Neftekum Formation of the Olenek Stage, which is composed of clayey limestones and mudstones. The content of total organic carbon (TOC) in limestones in the Eastern Fore-Caucasus area averages 0.1 % in some layers up to 2.05 %. The average TOC content in mudstones is 0.43 %. This parameter is up to 0.9 % in the direction of the East-Manych trough. Triassic deposits were penetrated by 5 wells, the average content of organic carbon was 1.22% in mudstones. The samples show a migrant presence of bitumen. According to 3D basin modeling results, the Olenek HC source rock has practically exhausted its potential in on most of the except the southern part of the study area, as well as the eastern flank. The Olenek stage's Neftekum HC source rock in the southern part of the model is identified with MK1-3 catagenesis gradations, this grade represents the main zone of oil generation. At the northern part of study area, those strata of source rock are positioned at a great depth. The hydrocarbon source rock in those areas have reached the grades of catagenesis MK5-AK1, which represents the zones of condensate and gas formation. The research results allow to take a new look at the influence of the Triassic hydrocarbon system and its prospects of petroleum potential of the Middle-Caspian Oil and Gas Basin. It also allows evaluating the generation parameters variance of the Olenek stage's Neftekum HC source rock regarding its area and time period.

Stability of a Petroleum-Like Hydrocarbon Mixture at Thermobaric Conditions That Correspond to Depths of 50 km

The commercial discovery of giant crude oil deposits at depths deeper than 10 km in various petroleum basins worldwide casts doubt on the validity of the theoretical calculations that have determined that the main zone of petroleum formation is at depths of 6–8 km (the ‘oil window’). However, the behavior of complex hydrocarbon systems at thermobaric conditions, which correspond to depths below 6–8 km, is poorly known. We experimentally investigated the thermal stability of a complex hydrocarbon system at the pressure-temperature conditions of Earth’s lower crust by means of Raman and Mössbauer spectroscopies. Our results demonstrated the chemical stability of the complex hydrocarbon system at thermobaric conditions corresponding to depths of 50 km, including the redox stability of the hydrocarbon system in a highly oxidative environment. The results of these experiments allowed us to revise the depth range in which petroleum deposits could occur.