Papers by Keyword: Formation

Abstract: Hydrogen and water adsorptions on the monolayer hexagonal boron nitride (h-BN) have been studied using the density functional theory. In this study, two configurations of monovacancy were modeled, i.e., monovacancy at the nitrogen site (V_N) and monovacancy at the boron site (V_B), by removing N and B atoms from the h-BN sheet, respectively. A supercell consisting of 32 atoms was used to analyze the adsorption of hydrogen and water (H₂O) by calculating formation and adsorption energies. From the calculated negative adsorption energies, we found that the involved reactions are exothermic, meaning that hydrogen and H₂O are easily adsorbed on the h-BN sheet. In addition, the hydrogen system at the V_B site was the most stable, as shown by the lowest formation energy of 2.78 eV.

Abstract: The paper analyzes the structure of coal beds. It is noted that coal beds belong to laminar massifs with characteristic oriented structure and pronounced anisotropy of strength properties, and include rock layers and consolidated hard inclusions. The quality criteria of the coal loosening process are highlighted. A selective method of separating coal from a massif by cutting along weakened surfaces is proposed as an alternative to the existing combine technology with continuous cutting of a massif from the surface.

Abstract: At present, most of the studies of the stability of the formation-cement sheath-casing combination have been mainly based on the plane, and the three-dimensional model established is only one example. There is no systematic study of the influence of physical parameters and process parameters on the stability of the combined body under the three-dimensional model and the action of triaxial crustal stress. Through the establishment of three-dimensional formation-cement sheath-casing linear elastic combination model, we can study the influence of operational parameters (cement sheath pressure, casing cross section pressure, inner casing pressure, ellipticity of borehole, centrality of casing, thickness of cement sheath) by the two interfaces’ Von Mises stress and the total displacement of the combination body. It is pointed out that the pressure of cement sheath, and casing cross section pressure have no effect on the stability of formation, cement sheath and casing; The higher the ellipticity of the borehole, the eccentricity of the casing (position 1, 2) and the thickness of the cement sheath, the higher the stability of the second interface of the cementing; The higher the inner casing pressure and the eccentricity of the casing(position 3), the lower the stability of the second interface of the cementing; The higher the eccentricity of the casing (position 2,3) and the thickness of the cement sheath, the higher the stability of the first interface of the cementing; The higher the inner casing pressure, the eccentricity of the casing (position 1) and the ellipticity of the borehole, the lower the stability of the first interface of the cementing; The higher the eccentricity of the casing (position 2,3) and thickness of the cement sheath, the higher the stability of the casing; The higher the inner casing pressure, the ellipticity of the borehole and the eccentricity of the casing(position 1), the lower the stability of the casing. Through this study, according to the formation stress, the formation physical parameters (elastic modulus, Poisson's ratio, density), optimize the operational parameters, ensure the long-term integrity of the combination.

Abstract: This paper considers the results of studies of the welded joints formation in conventional friction welding of pieces with different-sized cross sections. The features of the formation of joints associated with the asymmetry of the temperature field in the pieces are defined. The results of studies of the main parameters of the welding process are given which influence on the appearance, the microstructure of the joints and the valve after the stamp. The optimum parameters of the welding mode are set; recommendations are given.

Abstract: The Roslavl license block is one of the main assets of "RussNeft" company. Some particular perspectives of enhancing oil recovery are connected with this territory. The work objective was to define the perspectives of geological exploration, find new hydrocarbon deformational traps, and specify the geological structure of the already-known oil reservoirs in the Neocomian sediments, the Achimov strata, and Middle Jurassic sediments. The data analysis is necessary to create a new promising exploitation drilling program. The Roslavl license block is considered to be one of the most difficult and interesting areas in the sphere of hydrocarbon saturation perspectives from the quantitative aspects viewpoint. Different expectations on enhancing oil recovery in the Middle Ob oil and gas province of West Siberia are connected with this license block. Therefore, these perspectives were evaluated with the help of deep analysis of shooting data collected by seismic crews in different years, and the results of drilling. Different archival geological and geophysical evidence was analyzed to offer recommendations on the following geological exploration.

Abstract: Efficient development of oil reservoirs includes measures to restore and enhance the porosity and permeability properties of reservoir units that are gradually impaired during well operation. As a rule, various technologies of bottom-hole formation zone processing (BZP) of wells are used for these purposes. Special requirements to BZP technologies are applied during interventions in low-permeability reservoirs where the geological structure of reservoir units has the highest impact on the efficiency of works. In this relation, it seems interesting to study the specifics of geological structure of reservoir units in a laboratory for the efficiency of interventions using physical and chemical methods of reservoir stimulation. The research objective is to assess the efficiency of processing reservoir units with acid compositions of various concentration and type. Using laboratory experiments, physical and chemical parameters were quantitatively assessed that characterize the speed and depth of interaction between acid compositions and reservoir units.

Abstract: To increase the development efficiency of reservoirs, methods to intensify inflows and enhance oil recovery are applied. The geological and field experience of applying these methods shows that a high technological effect can be reached in specific geological and geophysical conditions while in other conditions efficiency will be insignificant. In this relation, an important solution for this problem is the justification of selecting the most efficient technologies of stimulating pay zones. The research objective is to select the most optimal technologies of stimulating pay zones to increase the development scope and enhance oil recovery. Using geological and field analysis, a complex quantitative assessment was done for the efficiency of using methods to enhance oil recovery and stimulate pay zones in both production and injection wells.

Abstract: The productive formations YUS₁¹ and YUS₁² are characterized by a strong lithologic and facies instability. The article shows the results of the analysis of the geological and technical interventions efficiency carried out on these sediments and defines their genetic dependence on the specific features of geological structure. The research objective is to analyze the geological structure of productive deposits, identify facies complexes and assess the effectiveness of geological and technical interventions. With the help of geological-field analysis, a quantitative evaluation of the technological effect obtained during the hydraulic fracturing of well formations, the repair and insulation works and a whole range of measures on intensification of inflow was carried out.

Abstract: An era of a high-gravity oil of the Samotlor field formations AV_2-5 and BV_8-10 is near to its end. The production deposits of the AV₁^1-2 horizon are the main reserve of oil production and the basic prospect in this area. Stratigraphically, the AV₁^1-2 horizon belongs to the Alym suite of the early Aptian Age that was distinguished as an individual unit at the 1967 interdepartmental stratigraphic meeting with the stratotype in the Uvat test well. This part of the section started to form around 400,000 years ago and is represented by siltites with interlays of clays and sandstones, primarily bioturbated ones, which causes the specific lens-clustered laminarity of these rocks (Ryabchik) with rare double leafs and single pancake-shaped primitive foraminifers such as saccamina. Specific features of the geological structure and oil-and-gas content of the AV₁^1-2 horizon within the area under consideration were in various aspects described earlier in the works of many researchers [1-8]. Nevertheless, when new geological and geophysical information had been accumulated, the need arose to cover this issue once again. Since it makes us consider the geological modeling of formations in the horizon from quite a different angle, we need to create various structural models of HC reservoirs, development flow diagrams, etc. The research objective is to define the genesis of producing deposits of the AV₁^1-2 horizon and identify fascia complexes in them. Using a system of special studies and methods for analyzing geological development and structure (paleotectonic, grain size, fascia, electrometric, etc.), the areas of sedimentation and fascia systems were diagnosed within the area under research.

Abstract: The choice of the most effective technology for reservoir completion depends mainly on the conditions for the formation of its constituent deposits and the specific features of their geological structure. This circumstance makes it possible to predict the productivity of newly drilled wells, transferred to the pay zone, as well as to plan the necessary geological and technical interventions with maximum efficiency. The research objective is to assess the influence of specific features of the geological structure of the production zone on the effectiveness of pay zones completion. Facies maps for productive formations were constructed with the help of paleogeographic and facies methods of analysis; a detailed geological and routine analysis made it possible to numerically assess the tightness of the connection between the development indices and the geological and geophysical characteristics of the objects under investigation.