Tatneft

The Ouan Kasa shaly sand reservoir in the Ghadames Basin of Libya presents significant challenges to drilling operations, particularly due to wellbore instability. The absence of prior geomechanical studies in this area raises concerns about the risks associated with drilling future wells. This study aims to construct one-dimensional mechanical Earth models (1D MEMs) to evaluate formation stability and define an optimal mud-weight window, thereby improving drilling efficiency and reducing operational risks. Data from two wells were analysed, including gamma-ray, sonic and bulk density logs, along with formation micro-imager (FMI) logs. Rock mechanical properties were derived using empirical correlations, the shear-wave velocity was estimated using the Greenberg-Castagna relationship and pore pressure was calculated using Eaton's method, calibrated against modular dynamic tester (MDT) data. Horizontal stresses were estimated using the poroelastic horizontal strain model, while stress orientations were inferred from FMI analysis. Results indicate that the Ouan Kasa Formation has a reduced mechanical stability due to its high shale content and ductile nature. A recommended mud-weight range of 11.2-14.5 ppg was identified to mitigate shear failure and ensure borehole integrity. In addition, the Devonian system is characterized by a normal faulting stress regime (sigma v > sigma(H) > sigma(h)), with the maximum horizontal stress orientated NW-SE (135 degrees) and the minimum stress orientated NE-SW. This study provides the first integrated geomechanical evaluation of the Ouan Kasa reservoir and offers valuable insights for drilling optimization and the safe development of future wells in the area.

The sequestration of carbon dioxide in depleted oil reservoirs is one of the ways to achieve zero emissions into the atmosphere This technology could become even more attractive if the sequestered carbon dioxide is reduced to methane by subsurface methanogenic archaea. The purpose of this work was to determine the physicochemical conditions and composition of the microbial community at the Biklyanskoe oil field before and after CO2 injection. The oil reservoir is characterized by an extremely high total mineralization of reservoir water (179.3 to 292.1 g L−1). Using high-throughput 16S rRNA gene V3–V4 fragments sequencing, aerobic organotrophic (genera Pseudomonas, Acinetobacter, Arcobacter, Thauera, and Sphingomonas), fermentative (Proteiniphilum, Anaerolinea, and Thermovirga), and sulfate-reducing bacteria (Desulfovermiculus and Desulfotignum), and methanogenic archaea (Methanohalophilus, Methanomethylovorans, and Methanosarcina) were detected in reservoir water and enrichment cultures. While CO2 injection did not lead to an increase in the number of fermentative and methanogenic prokaryotes in reservoir water, a decrease in pH, an increase in total mineralization, and in the concentration of calcium, magnesium, and bicarbonate ions revealed in the formation water were probably due to chemical processes. It is necessary to search for cheap processes/conditions/chemicals so that the process of bioconverting CO2 to methane can be effective.

The authors describe an extended network of high-precision levelling moves and a developed one of differential geodetic stations created at the complex geodynamic testing ground of PJSC ‘Tatneft’ in the oil-producing areas of Tatarstan Republic, RF. According to the results of 20-year repeated levelling measurements the manifestations of γ-type anomalies (local subsidence) were revealed, it characterises the zones of modern geodynamic activity. According to the extended time series data of the differential geodetic stations’ network coordinates changes, deformations of the earth surface as to two closely located points were revealed. The results of one combined point’s heights determining made by satellite method and levelling were compared. An extensive network of GNSS stations is actively used in geodetic and cadastral works, in search, exploration, development and arranging oil fields, in monitoring of regional geodynamic conditions

This article discusses innovative methods and technologies aimed at enhancing the efficiency of solar collectors. Various approaches are considered, including thin-film technologies, perovskite solar collectors, solar energy concentration technology, the use of nanomaterials, and the integration of solar collectors into architectural solutions. Special attention is paid to the significance of integrating solar collectors into architectural designs to enhance their efficiency. The article underscores the importance of innovations in solar energy for creating a sustainable and environmentally friendly energy future.

A new generation of oilfield equipment capable of safe operation for a long period in challenging conditions has appeared in recent years. In that context, it is of great interest to create high-quality materials with excellent mechanical properties and performance and to develop economical high-speed methods of producing such materials. The present work focuses on the advantages and disadvantages of current technologies and materials for the production of borehole pumping equipment and on recommendations regarding the selection of high-performance pumping equipment and its operating conditions.