This study presents an assessment of the hydrodynamic connectivity and compartmentalization of petroleum reservoirs in the Caspian Basin using integrated oil fingerprinting and biomarker geochemistry approaches. The aim of the study was to identify inter-reservoir fluid communication, reconstruct hydrocarbon migration pathways, and determine the factors controlling the geochemical heterogeneity of reservoir systems. The investigation was based on the analysis of 43 oil samples collected from 15 fields within the Caspian Basin using gas chromatography, gas chromatography–mass spectrometry, carbon isotope analysis, and multivariate statistical methods, including principal component analysis (PCA) and hierarchical cluster analysis. The results revealed the presence of both hydrodynamically connected reservoirs characterized by similar molecular and biomarker compositions and compartmentalized reservoir blocks showing significant geochemical differences and variations in thermal maturity. It was established that the internal heterogeneity of the reservoirs is controlled by tectonic segmentation, multi-stage hydrocarbon migration, and differences in source rock characteristics. The obtained results confirm the effectiveness of oil fingerprinting methods for diagnosing hydrodynamic connectivity and reservoir compartmentalization in complex petroleum systems.

Purpose.The research aims to conduct a comprehensive study on substantiation and selection of optimal parameters for supporting mine workings at deep levels by analyzing the stress-strain state (SSS) of the rock mass, modeling geomechanical processes and developing effective strengthening technologies in difficult geological conditions. Methods. The research includes modeling of the stress-strain state of the rock mass using ANSYS, Phase2 and Prorock software packages. To assess and predict the stress-strain state of the mass in the area of stope blocks, a series of numerical experiments have been conducted to analyze the near-contour rock mass stability. The physical-mechanical characteristics of ores and host rocks are used as input data for modeling. Findings. The mass SSS analysis has confirmed that increasing the number of cable bolts up to four provides mine wor-king stability, but is accompanied by intensive fracture formation beyond the contour, as well as convergence up to 14 cm, which requires the use of reinforcing mesh and reinforcing frame in two layers. The mining system elements have been found to provide the necessary safety factor for end ore drawing (ks ≥ 3.0) and slicing mining with hardening backfill (ks ≥ 5.0). Originality. The parameters for supporting mine workings have been substantiated, which ensures safe mining of deep levels. It has been revealed that when backfilling, the height of the caving zone is 125 m and the fracture zone is 60 m. For mining systems with caving, these figures reach 280 and 470 m, respectively. Practical implications. The technology has been developed for supporting capital mine workings with the use of reinforced combined support and roof bolts. The results obtained contribute to the improvement of reliability and efficiency of mining operations by providing accurate prediction of rock behavior under conditions of changing stresses and reduction of their strength characteristics.

This study presents an integrated geochemical approach to distinguish between genetic and reservoir-related factors controlling oil compositional variability, evaluate reservoir compartmentalization, and reconstruct hydrocarbon migration pathways within the Nuraly field and the Akshabulak group of fields in the South Turgay Basin, Kazakhstan. The study aims to develop and validate an integrated approach combining biomarker analysis and oil fingerprinting to improve the reliability of oil genetic interpretation, assess reservoir fluid communication, and reconstruct secondary hydrocarbon migration pathways. This study analyzed 164 unique crude oil samples from the Akshabulak and Nuraly fields. Oil fingerprinting was performed on all 164 samples, including 128 samples from the Akshabulak group and 36 samples from the Nuraly field. A representative subset of 75 samples, comprising 39 Akshabulak oils and 36 Nuraly oils, was additionally analyzed for biomarkers. Oil fingerprinting was conducted using low thermal mass multidimensional gas chromatography (LTM-MD-GC), whereas biomarker analysis was performed using gas chromatography–mass spectrometry (GC–MS). Principal component analysis (PCA) and hierarchical cluster analysis were applied separately to the oil-fingerprinting and biomarker datasets. The resulting classifications were subsequently compared and integrated to distinguish source-related genetic variability from reservoir-related compositional effects, including hydrocarbon migration, oil mixing, and reservoir compartmentalization. The proposed approach is based on the complementary diagnostic capabilities of the applied geochemical methods. Biomarkers provide information on the origin of organic matter, depositional environment, and thermal maturity of the source rocks, whereas oil fingerprinting is sensitive to hydrocarbon migration processes and the degree of hydrodynamic connectivity between reservoirs. The results indicate that the investigated oils are predominantly derived from terrigenous organic matter of lacustrine origin. The Akshabulak group is characterized by genetic homogeneity of oils despite pronounced reservoir compartmentalization, whereas the Nuraly field contains at least two genetically distinct oil populations and hydrocarbon mixing zones. Regional hydrocarbon migration was reconstructed from southeast to northwest. Paleochannel sandstones were identified as high-permeability migration conduits, while tectonic faults and facies heterogeneity were recognized as the principal controls on reservoir hydrodynamic isolation. The results demonstrate that integrating biomarker analysis with oil fingerprinting provides an effective tool for distinguishing between genetic and reservoir-related controls on oil compositional variability, evaluating reservoir compartmentalization, and improving the reliability of geological and reservoir models in structurally complex petroleum systems.

Petroleum reservoir systems of the South Mangyshlak Basin are characterized by a complex geological framework, pronounced geochemical heterogeneity, and evidence of inter-reservoir fluid interactions, which complicate the interpretation of oil origin and the assessment of geochemically inferred reservoir connectivity between productive horizons. In this study, a comprehensive geochemical characterization of crude oils from the basin was performed using high-resolution gas chromatography (HRGC), gas chromatography–mass spectrometry (GC–MS), oil fingerprinting, and Rock-Eval pyrolysis. The distributions of n-alkanes, isoprenoids, terpane, sterane, and aromatic biomarker compounds were analyzed to evaluate the genetic type of the source organic matter, thermal maturity, and hydrocarbon migration processes. The results revealed the presence of marine, lacustrine, and mixed genetic oil families, together with a general tendency toward increasing thermal maturity with reservoir depth. The most pronounced evidence of vertical hydrocarbon migration and oil mixing was identified in the Uzen oil field, where the multilayer reservoir system exhibits geochemical evidence consistent with possible inter-reservoir fluid communication and geochemically inferred reservoir connectivity. The obtained results suggest that the geochemical heterogeneity of oils in the South Mangyshlak Basin reflects the combined effects of variations in source-rock organic matter, vertical hydrocarbon migration, and oil mixing within stacked petroleum reservoir systems.

Purpose. The research aims to develop and substantiate an effective technology for supporting mine workings in conditions of complex geomechanical and hydrogeological factors based on the analysis of data on the border mass strain state, the effectiveness of the supports used, as well as the behavior of materials and structures in the process of operation. Methods. The research includes the use of endoscopic surveys of wells to diagnose the border mass for the purpose of identifying fractures, cleavages and other zones of weakening. The tests are conducted on the roof-bolting support including AK01-21N(U) and AK01-30PN rope bolts with a tension of up to 100 kN. Two-component resin (15 liters per blast-hole) and DAK-1-500 N resin capsules are used for complete filling of the blast-holes. In addition, the properties of MasterRock STS 1510 shotcrete support are studied with dynamic strength control. Findings. The border mass deformations have been revealed, including fracture opening up to 1.6 m, caused by the pre-sence of ore inclusions. The use of roof-bolting support with full filling of blast-holes with two-component resin and resin capsules has shown high efficiency. The AK01-30PN rope bolts with a tension of up to 100 kN have provided significant increase in the mass stability. MasterRock STS 1510 shotcrete has shown satisfactory strength characteristics. Minor fractures have been detected that do not influence the overall stability of the mine workings. Originality. The patterns of the border mass deformation behavior under conditions of complex geomechanical factors, including zones of fracturing and local weakening caused by ore inclusions, have been revealed and characterized. It has been found that complete filling of blast-holes with two-component resin and resin capsules for reinforcing rope bolts provides a significant increase in the mass stability. The integrated use of roof-bolting and shotcrete support has proven to be effective in reducing the impact of water inrush and increasing the strength characteristics of mine workings. Practical implications. The developed technology for supporting mine workings using rope bolts with tension up to 100 kN and full filling of blast-holes with two-component resin can be implemented at mining enterprises, which will increase the stability of mine workings and safety of operations in conditions of complex geomechanical factors. The results of endoscopic diagnostics and monitoring of the border mass deformations provide a tool for timely identification of weakening zones and taking measures to strengthen the support, contributing to increased efficiency during mine working operation.

Background: Corrosion is among the primary factors that diminish the reliability and service life of oil pipelines. Among the existing corrosion-mitigation techniques, cathodic (electrochemical) protection is widely regarded as the most effective method, enabling a substantial extension of pipeline longevity and a significant reduction in operational risks. Aim: The aim of this study is to calculate and analyze the key parameters of cathodic protection stations to ensure effective electrochemical protection of oil pipelines, enhance the reliability of their operation, and prevent corrosion-related degradation. Materials and methods: The study relied on the regulatory document RD 153-39.4-039-99 and methodological guidelines for the design of electrochemical protection systems. Calculations were performed using the established formulas proposed by Bykov et al. (2006), incorporating soil resistivity as well as the length and geometric parameters of the pipeline. Additionally, the analysis examined how potentials, currents, and resistances are distributed within the pipeline–soil system. Results: The study identified the optimal design parameters for cathodic protection stations, including current load, the required number of anodes, grounding resistance, and power supply capacity. The findings demonstrate that properly selecting these parameters helps maintain a stable protection potential and significantly enhances the operational lifetime of the pipeline. Conclusion: Implementing cathodic protection based on accurately calculated design parameters enhances the operational safety of oil pipelines, mitigates corrosion-related risks, and reduces the overall maintenance costs.