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Date submitted2021-02-09
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Date accepted2023-09-20
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Date published2024-02-29
Analysis of experience in the use of preformed particle polymer gels in the development of high-water-cut production facilities in low-temperature oil reservoirs
- Authors:
- Sergei V. Galkin
- Yuliya A. Rozhkova
Foreign practice of oil production in high-water-cut conditions suggests using the technology of injection of preformed particle gel (PPG) suspension into injection wells. After swelling, the polymer particles become elastic and are able to penetrate through highly permeable watered intervals into the remote reservoir zone, forming a polymer “plug”. Thus far, the domestic experience of application of this technology boiled down to testing foreign compounds. We have looked into the possibilities of PPG technology application in geological and technological conditions of high-water-cut fields of Perm Krai. The paper proposes PPG reagents effective in low-temperature reservoirs (20-35 °С) and at relatively high salinity of formation water (more than 200 g/l). The world experience of PPG technology application was analyzed to identify the principal scheme of reagent injection, to establish variants of sequence of injection of PPG particles of different sizes, as well as the possibility of regulating the morphological characteristics of polymer gel particles during synthesis depending on the porosity and permeability of the reservoir. A prerequisite for the technology is the ability to remove PPG particles after treatment from the bottom-hole zone of the formation; for this purpose, tests were carried out on a breaker compound based on sodium persulfate with synergizing additives. PPG technology is effective in reservoirs with high permeability heterogeneity. Two types of high-water-cut production facilities potentially promising for PPG realization have been identified for oil fields of Perm Krai. The first type includes carbonate Tournaisian-Famennian reservoirs with pronounced macrofracturing, in which the PPGs are used for colmatation of flushed large fractures. The second type is terrigenous Visean deposits with increased oil viscosity from 5 to 100 mPa∙s and high permeability of reservoirs (> 0.5 μm2). For both types of reservoirs, areas have been selected that are promising for the implementation of PPG technology.
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Date submitted2021-04-26
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Date accepted2021-07-27
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Date published2021-10-21
Study of the dynamics for gas accumulation in the annulus of production wells
Accumulation of associated petroleum gas in the annulus is one of the negative factors that impede the intensification of mechanized oil production. An increase in annular gas pressure causes growth of bottomhole pressure, a decrease in back pressure to the formation and the inflow of formation fluid. In addition, accumulation of gas in the annulus leads to displacement and a decrease in the liquid level above the submersible pump. Insufficient level of the pump submersion (rod or electric submersible) causes a number of complications in the operation of mechanized production units associated with overheating of the elements in pumping units. Therefore, the development of technologies for optimizing the gas pressure in the annulus is relevant. Method for calculating the intensity of gas pressure increase in the annulus of production wells operated by submersible pumps has been developed. Analytical dependence for calculating the time interval of gas accumulation in the annulus, during which the dynamic level decreases to the pump intake, is obtained. This value can be used to estimate the frequency of gas withdrawal from the annulus using compressors. It has been found that the rate of increase in annular gas pressure in time increases non-linearly with a rise in the gas-oil ratio and a decrease in water cut, and also linearly increases with a rise in liquid flow rate. Influence of the operating (gas-oil ratio) and technological (value of the gas pressure maintained in the annulus) factors on the flow rate of the suspended reciprocating compressor driven by the beam engine, designed for forced withdrawal and redirection of the annular gas into the flow line of the well is analyzed.
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Date submitted2020-07-02
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Date accepted2021-02-16
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Date published2021-04-26
Development of viscoelastic systems and technologies for isolating water-bearing horizons with abnormal formation pressures during oil and gas wells drilling
Article provides a brief overview of the complications arising during the construction of oil and gas wells in conditions of abnormally high and abnormally low formation pressures. Technological properties of the solutions used to eliminate emergency situations when drilling wells in the intervals of catastrophic absorption and influx of formation fluid have been investigated. A technology for isolating water influx in intervals of excess formation pressure has been developed. The technology is based on the use of a special device that provides control of the hydrodynamic pressure in the annular space of the well. An experiment was carried out to determine the injection time of a viscoelastic system depending on its rheology, rock properties and technological parameters of the isolation process. A mathematical model based on the use of a special device is presented. The model allows determining the penetration depth of a viscoelastic system to block water-bearing horizons to prevent interformation crossflows and water breakthrough into production wells.
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Date submitted2019-08-08
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Date accepted2019-09-16
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Date published2020-02-25
Testing of preformed particles polymer gel technology on core filtration models to limit water inflows
In order to reduce watering of wells and equalize their injectivity profiles, the prospects of introducing PPG technology in Russian fields are considered, in which preformed particles polymer gel are pumped into the injection well. These particles, being a supersorbent based on polyacrylamide, absorb water, become elastic, which allows them to shrink and tear in narrow filtration channels. When the polymer is filtered along permeable layers saturated with water, polymer particles accumulate in waterlogged intervals and thus they form a polymer plug, which redistributes the filtration flows and increases the coverage of the formation by the process of oil displacement. More than 4000 downhole operations have been carried out in the fields of China and the USA using PPG technology by now. In domestic fields in Western Siberia, there is limited experience in applying a similar technology in high-temperature formations with low mineralization of formation water. Due to the absence of hydrolytic processes in polyacrylamide, well-known domestic compositions are not applicable due to the low absorption capacity in the conditions of low-temperature deposits with increased mineralization of formation water. The authors synthesized a polymer based on polyacrylamide by block polymerization, which allows to obtain a high absorption capacity, including for low-temperature formations with high mineralization of formation water, which is typical for Perm Territory fields. Filtration experiments were carried out on core models with the composition developed by the authors, this composition focused on low formation temperatures and high mineralization of formation water. As a result of the experiments, it was found that the swollen particles of the gel are able to pass into fractures with a diameter less than their own size at least 20 times. With a significant increase in the viscosity of the dispersion medium, the stability of the suspension increases. Particles of polymer gel have the necessary strength for injection in the field conditions. The fracture permeability during polymer injection decreases by several times and becomes comparable with the permeability of pore collectors.
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Date submitted2018-01-04
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Date accepted2018-03-08
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Date published2018-06-22
Influence of mining-geological conditions and technogenic factors on blastholes stability during open mining of apatite-nepheline ores
- Authors:
- M. N. Overchenko
- S. A. Tolstunov
- S. P. Mozer
The paper presents the results of borehole stability research and considers possible causes of emergencies. The features of the blast hole drilling process are analyzed taking into account the properties of the rock. Based on the distribution of speed of drill fines removal from the well, an algorithm for selecting drilling modes is proposed. The nature of change in the size of the holess over time has been analyzed. This paper investigates the influence of rock fracturing and its water content on borehole stability. Possible options for eliminating the man-made impact on the massif near holes and options for fixing the hole walls with soft shells are suggested. The experimental data on the installation of shells for the conditions of open mining of apatite-nepheline ores are given. The operability and effectiveness of the technology is proved.
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Date submitted2015-07-05
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Date accepted2015-09-01
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Date published2016-02-24
Substantiation of intrastratal water shutoff technology in low permeability reservoirs
- Authors:
- M. K. Rogachev
- A. O. Kondrashev
The article presents the results of the filtration tests of the developed polymeric waterproofing compound GPS-1, which is a mixture of a water-alkaline hydrolyzed acryl-containing polymer solution with a nonionic surfactant. The obtained results indicate significant improvements of main operational parameters – penetrating and water-insulating power of the developed polymeric composition GPS-1 in comparison with the original one: addition of the nonionic surfactant reduced the pressure gradient of injection twice. Also, considerable (5 times) increase of the residual resistance factor, that is explained by deeper and more uniform penetration of the solution into the porous medium and the corresponding raise of isolation efficiency of pore channels, is established. Experiments on the model of a heterogeneous oil-filled formation showed that after the injection of the polymeric solution water mobility decreases in a highly porous interlayer and increases in a low-permeability interlayer indicating a redistribution of filtration flows in the model of a heterogeneous bed. The decrease of water mobility in a high-permeability zone contributes to the leveling of the displacement front and, ultimately, the additional extraction of oil from the less permeable area. As a result of the complex of filtration tests conducted, the efficiency of the developed polymeric composition GPS-1 for the regulation of filtration flows in low-permeability heterogeneous reservoirs is proved.