The article presents the derivation of generalized formulas for the flow rate of a vertical well with a radial steady-state inflow of liquid for cases of deviation from Darcy’s law. Graphs of the flow rate dependence on the pressure gradient are presented and the time of water breakthrough during non-piston displacement of oil by water for various filtration laws is determined.
A probabilistic assessment of Upper Devonian carbonate targets is presented, taking into account reservoir heterogeneity, depositional conditions and the preservation of hydrocarbon accumulations. The distinct geological characteristics of the Zavolzhsky, Dankovo-Lebedyansky, Elets and Evlanovo-Liven horizons are retained. Palaeogeographic and predictive maps are linked to resource assessment, a five-factor model of geological chance of success (gCoS) and scenario-based calculation of expected monetary value (EMV). An economic assessment framework is illustrated using a Dankovo-Lebedyansky target as an example. The value of additional information (VOI) is considered as a basis for selecting further studies.
Over the course of eight decades, PJSC Tatneft has consistently developed its reservoir pressure maintenance (RPM) system, transforming it into a well-tuned technological organism. Today, the RPM infrastructure is a harmoniously structured complex covering the entire cycle of working agent injection: from water intake and treatment to its injection into the reservoir.
Striving for maximum efficiency, the company relies on three key components - energy efficiency, reliability, and controllability. As part of increasing energy efficiency, a large-scale renewal of the pump fleet is underway: former solutions are being replaced by positive displacement units with a high efficiency of 80–86 %, which significantly reduce energy costs. An equally significant step has been the transformation of the pipeline network: the use of fiberglass and flexible composite pipes has made it possible to reliably resist corrosion and aggressive environments. At the same time, engineers do not limit themselves to replacing materials; they also adjust the very geometry of the system: regrouping the pipeline network, laying jumpers, and redirecting flows. Such comprehensive optimization of routes helps to tame hydraulic losses and noticeably reduce energy consumption.
As part of the downhole equipment of injection wells, fiberglass tubing (tubing) is increasingly being used - its share in well equipment is steadily growing. The accumulated experience has made it possible to develop standard downhole equipment configurations for various conditions - taking into account depth, wellbore trajectory, and environment aggressiveness. The standardization of solutions has accelerated preparation for tripping operations, while the localization of production at the company's own facilities has ensured rapid replication of technologies and increased the reliability of the injection well stock.
A key milestone on the path of improvement has been digital transformation. Its basis is the subsequent introduction of digital twins, which will combine telemetry, hydraulic calculations, and geographic information system data. In conjunction with automation, this will create a unified closed loop of "monitoring — analysis — control": the system will allow real-time recording and adaptation of changes in pipelines and equipment, enabling flexible and precise adjustment of injection regimes.
This paper proposes a method for diagnosing bottomhole rod parting or twist-off and transmitting data from the bottomhole to the wellhead via an electrical circuit consisting of the "sucker rod string – downhole pump – tubing string". This approach aims to improve the reliability of identifying the causes of unscheduled shutdowns and to optimize workover planning.
Theoretical calculations of the electrical resistance for both closed and open circuits were performed. Field resistance measurements were conducted on 10 producing wells using an APPA 62 digital multimeter, alongside an analysis of electromagnetic interference using an AKIP-4107 oscilloscope.
The method was field-tested on three wells at the Yelnikovskoye field (wells 68A, 4051, and 2823), which had preliminary diagnoses of rod parting/twist-off based on dynamometer cards. It was established that the average measured resistance of a closed circuit is 2.5 Ω (calculated value: 1.41 Ω), whereas simulating a parting (e.g., an unseated pump) causes the resistance to increase to 6–1000 Ω (calculated value: 200 Ω). This difference in orders of magnitude confirms the technical feasibility of reliably transmitting discrete signals. Field tests demonstrated that in the event of a bottomhole rod parting or twist-off, the circuit resistance increases to the megaohm range (e.g., 3.79 MΩ for well 68A). This provides unambiguous identification of a parting, unlike traditional dynamometer card analysis, which cannot reliably differentiate between rod parting/twist-off and pump valve malfunctions.
The developed method enables reliable detection of bottomhole rod parting, thereby eliminating unjustified costs associated with unnecessary "recovery" operations (such as flushing with hot oil, water, or solvents) and reducing well downtime. A limitation of this method is the risk of parasitic short circuits between the rods and the tubing in deviated wellbore sections; however, this can be mitigated by using sucker rods equipped with polymer scraper-centralizers.
The paper considers the formation conditions of the Visean (Bobrikovian) terrigenous deposits of the Volga-Ural anteclise and proposes a tool for rapid assessment of their oil potential within licensed fields and unallocated subsoil areas. The productivity of the Bobrikovian horizon is largely controlled by depositional environments, facies affiliation and lithological variability of the rocks; therefore, a forecast based only on the structural position of an object is insufficient. The objective of the study is to develop a tool for rapid assessment of the oil potential of the Bobrikovian deposits that takes into account their formation conditions depending on the depositional environment. Stratigraphic schemes, paleogeographic maps, archive reports, well data and materials of ongoing projects were integrated into a single digital database; paleogeographic reconstructions were digitized and facies zoning of the horizon was performed. Six facies zones were identified: crystalline basement highs, alluvial plain, alluvial-deltaic plain, deltaic plain, delta front and open shelf. For each zone, the formation conditions and reservoir parameters were characterized: net-to-gross ratio, shale content, porosity and permeability. It has been established that the most favorable conditions are associated with the deltaic (average net-to- gross ratio 0.81) and alluvial-deltaic (0.67) plains, which are classified as highly prospective zones; the alluvial plain and delta front are classified as moderately prospective, and the open shelf and basement highs as low-prospective. An algorithm of rapid assessment and a scheme for ranking areas are proposed, including comparison of the facies map with unallocated subsoil areas. A SWOT analysis was performed, and the limitations of the approach and directions for its further development were identified.
