Vol 21, No 4 (2021)
- Year: 2021
- Articles: 8
- URL: https://ered.pstu.ru/index.php/geo/issue/view/151
Abstract
Investigations of the petrophysical properties of deposits in the Khizin zone have been carried out in several fields. In the study area, the Lower Cretaceous complex mainly consists of carbonate and clay formations. The lithological composition and sizes of rock fragments vary sharply within a small range of depth. The Lower Cretaceous deposits are exposed at depths of 450-1815 m; with an increase in carbonate and clay content of rocks, the porosity naturally decreases in this interval. According to petrophysical investigations, it can be concluded that with an increase in depth, a certain change in the reservoir properties of rocks occurs, that is, with a decrease in porosity of rocks, an increase in carbonate and clay content is observed. When predicting the oil-and-gas-bearing capacity of deep-seated strata in the area under consideration, it is advisable to use not only field geophysical techniques, but also a characteristic change in the porosity of rocks with depth revealed by petrophysical investigations. In the southeastern Khizin tectonic zone, on the eastern flanks of Sitalchay and Shurabad uplifts, Cenomanian deposits are more common. Among the greenish-gray clays in the section, there are widespread calcareous-clayey gravelstones, limestones, sands and sandstones. In the central part of this zone, the section is composed of greenish-gray clays with siltstone interlayers. Gravelite and sandy siltstones reappear in the Senomanian section, south of Atachai. There are also breccia conglomerates in the Bayimdag-Takchay, Sitalchay-Yashma and Shurabad areas. In the Zoratmulda area, the upper part of the Cenomanian is distinguished with the Zoratsky horizon composed of bituminous clays. In the southeastern Khizi tectonic zone, the floor thickness reaches 200 m. According to the data provided, it can be concluded that in the Khizi tectonic zone, oil and gas shows were recorded in all sections of Mesozoic sediments exposed by drilling. The observed oil and gas fountains occurred during the Alba (Shurabad), Valandzhin (Begimdag-Tekchay) and Middle Jura (Keshchay) strata penetration.
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Abstract
Realisation of the issue for hydrocarbon deposit exploration and development, which are associated with non-anticlinal traps, has been given the utmost attention in recent years, since this is precisely the solution to the problem of providing proven oil and gas resources in the areas with developed oil production, where the main and general exploration directions are already largely worked out. In this regard, the search for non-anticlinal traps in the Upper Devonian-Tournaisian carbonate complex of such an old oil and gas producing region as the Volga-Ural Oil and Gas Province is highly relevant. The types of non-anticlinal hydrocarbon traps found in the Upper Frasnian-Tournaisian carbonate deposits in the Perm Territory and the Udmurt Republic are considered, and their lateral distribution zones are identified. Among the many classifications, the genetic classification of non-anticlinal traps by N.S. Oknova et al. (1999) has been chosen as the basic one. Within the study area, lithologically screened traps limited by facies changes have been identified. Among the ones limited by facies changes, a biogenic subtype of traps has been found. Similar traps occur in reef systems, solitary reefs, banks, bioherms, biostromes, etc. Lithologically screened traps are formed as a result of updip reservoir pinchout or their facies replacement by low-permeable coeval rocks. Among them, traps in complex clinoform bodies of the Tournaisian infill are of particular interest, since the prospects for discovering new oil-bearing places associated with Late Devonian reef massifs are decreasing from year to year due to their high level of exploration. In the study area, we have traced five zones of the of non-anticlinal trap distribution.
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Abstract
Various enhanced oil recovery technologies based on the injection of various gases into the reservoir have been successfully used abroad, especially in the United States, since the middle of the 20th century. Carbon dioxide has received the greatest application as a reservoir influencing agent, since it can dissolve in large amounts in oil under reservoir conditions, and also demonstrates a phase behavior that is convenient from a process-oriented point of view. However, in Russia the technology of CO2 injection in order to increase oil recovery has not become widespread due to the absence of large natural sources of CO2. Nevertheless, due to the need to comply with the terms of the Paris Agreement on reducing greenhouse gas emissions, LUKOIL has been paying more and more attention to the development of technologies for utilisation of technogenic greenhouse gas, including associated petroleum gas. This paper presents the results of laboratory investigations to assess the prospects for the application of an enhanced oil recovery technology at the Tolumskoye field by injecting the high CO2 associated petroleum gas, the source of which is the Semividovskaya group of fields. The effect of concentration of associated petroleum gas on reservoir oil properties was studied, the mode of oil displacement by associated petroleum gas was assessed, ratios of oil displacement by water and the model of associated petroleum gas and relative phase permeabilities on core models of the Tolumskoye field were determined. The results of laboratory investigations were used for the further stage of hydrodynamic modeling, which was carried out to select the most optimal associated gas injection technology and to perform a technical and economic assessment of associated gas injection technology to enhance oil recovery from hard-to-recover reserves of the Tolumskoye field.
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Abstract
Currently, most residual recoverable oil reserves of the fields are located in complex layered heterogeneous carbonate reservoirs. Improving the efficiency of field development in conditions of uneven development of reserves along the section is complicated by an increase in water cut that occurs as reserves are recovered. In this regard, the process of searching for candidate wells for acidising becomes more complicated, and there is a need to use new technologies for stimulating the formation. In particular, the use of diverting agents in hydrochloric acid treatment often becomes a prerequisite for a successful treatment of the bottom-hole zone. The results of laboratory studies and work performed in wells are generalised and analysed, as well as the correctness of methodological approaches in studies of self-deviating acids is confirmed, taking into account the actual results obtained on wells. The results of laboratory investigations of self-deviating acids in the "free volume" and on core material are described, the testing of acid compositions in four wells, including the results of flow measurements before and after treatment, is analysed. The analysis of works showed that according to the results of flow measurements carried out in the wells, the inflow profile redistribution was recorded, which was also noted at the stage of filtration studies on two-layer multi-permeable models. The promising areas for applying self-diverting acid are wells with intervals not connected to development in the presence of permeability contrast, including after standard acid treatments. It is necessary to test the technology at objects with a small formation thickness to ensure a higher specific reagent consumption, taking into account the high cost of self-diverting acids.
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Abstract
The degree of oil field development efficiency in Western Siberia largely depends on the state of the bottomhole formation zone of production and injection wells. Due to the dropout of various reaction products, after the introduction of chemical reagents, filtration parameters and permeability of the bottomhole formation zone decrease during the development process. Today, various processing technologies are used to restore the filtration characteristics of the bottomhole zone, one of which is acid treatment. The pace of the oil and gas industry development in recent years leads to the fact that such stimulation methods as hydraulic fracturing or acid treatment are used in the development and commissioning of wells. Acidizing is increasingly being used to bring production wells into production after drilling or killing during workovers. Despite the fact that acid treatments have been used in the oil and gas industry for a very long time, all the problems that arise during their implementation have not been fully resolved. This treatment is one of the most effective, widely used and relatively inexpensive method of increasing the productivity of production wells or restoring the injectivity of injection wells. In this regard, the methods of acid treatment at two fields have been studied and an analysis of their performance has been carried out. For the target goal, the following tasks were solved: geological and production data for fields analysed; current state of fields development analyzed; acid treatment process analyzed on the basis of domestic and foreign experience for the selection of technological and process parameters taking into account specific conditions; efficacy of acid treatment at fields analyzed.
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Abstract
As a result of oil and gas well operations, they are regularly clogged with asphalt-resin-paraffin sediments (ARPD) and gas hydrates, which significantly complicates the oil and gas production up to the complete well shutdown. The paper presents a new promising technology, and the special developed equipment for cleaning oil-well tubing and annular space of oil and gas wells. The process principle is to initiate an exothermic process inside the oil-well tubing by a chemical reaction of alkali or alkaline earth metals (groups I, II of the periodic table of Mendeleev's Periodic Table) with water or acid, as a result of which a large amount of heat is generated, leading to the effective decomposition of asphalt-resin-paraffin sediments and gas hydrates both inside the oil-well tubing and in the annular space. Metallic sodium and metallic calcium were tested as heat-transfer metals, their effectiveness was compared. The results of pilot industrial tests in oil fields are presented. Techniques for eliminating sediments with thermochemical devices in situations often occurring in the process of oil production are proposed: cleaning the annular space from gas hydrate sediments, eliminating wax and gas hydrate sediments inside the oil-well tubing, cleaning when the bottomhole communicates with the wellhead through the pipe channel.
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Abstract
A mathematical model of liquid droplet circulating motion in a gas medium has been developed, the use of which makes it possible to create more efficient methods of dust collection. High dustiness of the work space in the collieries, active methane emissions restrain the intensification of coal mining, reducing the competitiveness of mining enterprises. The analysis showed that the occurrence of explosion hazard can be prevented by effective dust collection. The most common method is dust deposition based on wetting dust particles with liquid droplets to form a dust particle-liquid droplet system, which settles on the walls of mine workings. However, with an increase in fluid pressure, energy consumption for dust collection increases significantly, which worsens the parameters of energy efficiency while observing hygiene requirements. Based on study results for physical features of the inertial motion of rotating liquid droplets, a mathematical model of their circulation in a gas medium has been developed to create more efficient dust collection methods. It is proved that the vorticity diffusion equation for a liquid droplet moving along a helical line is identical to the heat conduction equation with a dispersion coefficient of the rotational motion energy of a liquid droplet with a coefficient that is the dynamic viscosity coefficient. It is confirmed that the circulating motion of liquid droplets in both the Nad-Stokes and Stokes motion increases the relaxation time due to a decrease in aerodynamic drag coefficient of the gas medium caused by an increase in the effective Reynold's number with an increase in the angular rotation velocity of liquid droplets. It is shown that averaging the aerodynamic drag coefficient values of the liquid droplet motion makes it possible to use the obtained formulas for calculating hydro-vortex coagulation in a wide range of Reynold's number 1 <Re <104.
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Abstract
Current problems of the methodology for assessing occupational hazards, which is an integral part of the risk-oriented approach to the occupational and industrial safety management at mining enterprises, are considered. The variety of mining-geological and mining-technical conditions of underground mining inevitably requires the development of adequate and effective methods of risk assessment, on which all future methods of engineering and organisational occupational and industrial safety management are structured. The voluntariness and variability of risk assessment procedures in international practices and the obligation of detailed regulation in Russian practice, as well as the complexity of this new target for the practice of Russian mining enterprises, the recognition and solution of which by specialists have just begun, led not only to the lack of generally recognised risk assessment methods, but also to the methodology of their development in relation to labour conditions at Russian mining enterprises. Based on a critical analysis of the structure and content of hazards and risks at underground mining enterprises, methodological techniques for constructing effective risk assessment methods have been formulated. The main attention is paid to the assessment of occupational hazards of anatomical injury or acute inhalation poisoning. A detailed step-by-step analysis of any occurred adverse event (an accident in the course of a working person's performance of his/her labor function) has been carried out. Originating point is the concept of working environment and labor process “property”, which may cause harm of varying severity, up to the death of the effected person, in case of accidental contact effects on the employee's body. It is shown how the logically related concepts of “hazard”, “occupationally significant hazard”, “hazard carrier”, “hazard source” allow us to build a clear procedure for identifying occupationally significant hazards and to logically carry out the procedure for risk assessment, including the assessment of various risk types by their level (degree) of admissibility and priority of making management decisions and protective measures. This article reveals the essence of the problem and provides examples of drawing the specific methods, identifying and overcoming the "bottlenecks" of risk assessment at mining enterprises. The study results are applied practically and can be recommended to specialists when assessing occupational hazards at mining enterprises.
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