Petroleum-Gas University of Ploiești

This study presents the results of an integrated study of the petrophysical and lithological properties of Jurassic and Triassic rocks in the Morskoye field and the Ogayskoye block, within the Caspian Basin. The research aims to refine reservoir evaluation parameters through detailed laboratory analyses of core samples with geophysical well log interpretation. Core material from 23 wells (1980 samples) was analyzed using mineralogical, granulometric, and petrophysical methods, with additional verification from seismic data and well test results. Mineralogical studies based on X-ray diffraction confirmed the predominance of quartz, carbonates, and clay minerals, while granulometric analysis revealed the dominance of fine-grained and pelitic fractions, explaining the generally low filtration capacity of the studied reservoirs. The laboratory experiments established robust empirical relationships between porosity, permeability, and saturation parameters. Strong statistical reliability was achieved, particularly for the K1al-K1nc stratigraphic intervals, where reservoir properties demonstrated stability and consistency. A clear linear corre-lation between bulk density and porosity was identified, allowing accurate determination of the matrix density (2.69 g/cm3) used in quantitative well log interpretation. Special attention was given to the recognition of thin coal interbeds within Jurassic deposits. These intervals showed distinctive geophysical responses, including abnormally high neutron porosity and low bulk density, and were systematically excluded from reservoir classification to avoid misinterpretation. Phase permeability tests demonstrated the significant influence of residual oil and water saturations on multiphase flow behavior, offering insights into displacement efficiency and fluid mobility within pore networks. The study also determined lithology-and depth-specific threshold values of porosity and permeability, which enhance the accuracy of identifying and delineating productive intervals. The results provide a reliable methodological foundation for improving reservoir characterization, refining hydrocarbon reserve estimation, and supporting exploration and development strategies in geologically complex settings.

At present, most oil-producing countries are developing fields with hard-to-recover oil reserves. To achieve high technological and especially economic indicators, it is necessary to apply methods that influence oil-bearing formations. Enhanced Oil Recovery (EOR) methods are among the most relevant tasks of modern oil production, since they make it possible to increase the oil displacement coefficient in individual zones that were previously unaffected, as well as in the reservoir as a whole. In addition, they help improve the main parameters of oil mobility within the formation. Most physico-chemical methods for increasing oil recovery are based on the properties of oil droplet detachment from the pore surface. These properties include wettability, adhesion, interfacial tension, and capillary pressure. For this purpose, a methodological approach is required to determine an effective chemical agent. This involves conducting laboratory studies of the physicochemical properties of the proposed agent (in our case, an alkaline solution) and, based on these results, determining its optimal concentration. Laboratory studies of the properties of the agent and oil were carried out using the following instruments: a Contact Angle Meter SDC-100, the <> method (rotating drop), and a stalagmometer for calculating capillary pressure. To verify the reliability of the obtained results, they were tested on a reservoir model. For this purpose, experimental studies of oil displacement from the formation using an alkaline solution with optimal concentration were carried out. The obtained results showed good efficiency of this technology. Moreover, the higher the concentration, the higher the oil displacement coefficient.

The impact of aluminum doping on the structural properties and Rhodamine B (RhB) adsorption performance of three mesoporous silicas (MCM-41, MCM-48, and SBA-15) was systematically investigated. Al-doped materials were successfully synthesized via in situ co-condensation using aluminum chloride as the Al source (3 wt% Al loading). Characterization by XRD, FT-IR, N-2 physisorption, SEM-EDS, and TGA confirmed the successful incorporation of aluminum into the silica framework, while largely preserving the mesoporous structure and morphology. Adsorption experiments were conducted under optimized conditions (0.010 g adsorbent, 25.0 mL RhB solution, 200 rpm, pH 5-6). The kinetic data were best fitted by the pseudo-second-order (PSO) model (R-2 = 0.9899-0.9966 for most samples), indicating that the adsorption process is mainly governed by surface-controlled interactions, including electrostatic attraction, hydrogen bonding, and pi-pi interactions, rather than true chemisorption. Equilibrium isotherms are best described by both the Langmuir and the Freundlich models, indicating mixed adsorption behavior involving monolayer adsorption on homogeneous sites, surface heterogeneity, and possible multilayer adsorption. Aluminum doping significantly enhanced the maximum adsorption capacity (q(max)), increasing from 40.8 to 62.9 mg g(-1) for MCM-41, from 81.9 to 136 mg g(-1) for MCM-48, and from 52.6 to 163.3 mg g(-1) for SBA-15. The highest adsorption performance was observed for Al-SBA-15, followed by Al-MCM-48, due to the increased number of active sites and enhanced surface acidity after Al incorporation. FT-IR analysis confirmed the successful adsorption of RhB through the appearance and shift of the aromatic C=C band from 1579 cm(-1) to 1556-1573 cm(-1), indicating interactions between RhB molecules and surface silanol and Al-OH groups. The Dubinin-Radushkevich model further revealed low adsorption energy values, confirming that the adsorption mechanism is predominantly physical (physisorption). Thermodynamic studies in the temperature range of 20-50 degrees C revealed that the adsorption process is spontaneous (Delta G degrees < 0), exothermic (Delta H degrees < 0), and accompanied by a decrease in entropy (Delta S degrees < 0), indicating reduced randomness at the solid-liquid interface during adsorption. Aluminum doping further increased the spontaneity of the process, particularly at lower temperatures. Overall, aluminum incorporation improves the surface acidity, active site density, and adsorption efficiency of mesoporous silicas, resulting in superior RhB removal performance. Among the investigated materials, Al-SBA-15 and Al-MCM-48 proved to be the most efficient and reusable adsorbents, demonstrating high adsorption capacity, structural stability, and excellent regeneration ability, making them promising candidates for removing cationic dyes from wastewater.

This paper investigates submanifolds immersed in a conformal Kenmotsu space form endowed with a quarter-symmetric connection recently considered by Qu and Wang (J Math Anal Appl 431(2):955–987. 2015). By employing the concept of generalized normalized δ -Casorati curvature in conjunction with scalar curvature, we establish sharp and optimal inequalities that clarify the relationship between the intrinsic and extrinsic geometry of the submanifold. Furthermore, we explore the equality cases of these inequalities, discuss their geometric implications and deduce several consequences. To substantiate the theoretical developments, we construct two explicit examples to illustrate the validity and applicability of the derived results.

The article investigates the causes of failures of downhole pumping equipment (DPE) used in mechanized oil production, as well as methods for analyzing and forecasting its reliability. Despite continuous improvements in pump design and materials, a significant proportion of failures is associated with the effects of abrasive particles, corrosion, and cavitation. An analysis of domestic and foreign studies aimed at identifying patterns of failure mechanisms and increasing the mean time between repairs (MTBR) of pumps has been carried out. It has been determined that the key factor affecting the reduction in efficiency and durability of the equipment is the presence of mechanical impurities, as well as their concentration, shape, and grain-size distribution. Based on data from oil fields in Kazakhstan, Russia, and Azerbaijan, fuzzy clustering of operating conditions was performed, which allowed the identification of four groups of objects with different combinations of factors. Threedimensional dependencies were constructed, and the results of the analysis formed the basis for fuzzy logic rules & laquo;if..., then...& raquo;. The application of fuzzy cluster analysis confirmed the effectiveness of this method in solving diagnostic and optimization problems in oilfield equipment operation. Based on the results of the analysis, a new-generation filter element was developed, demonstrating significantly higher efficiency compared to leading global analogues and successfully implemented at one of the fields in Serbia. The results obtained can be used to improve the reliability of downhole pumps, reduce failure frequency, and form a knowledge base for managerial decision-making in oil production.