Displacement Process Research Articles

Rheological properties of polymer solutions and ways to improve the efficiency of development of high-viscosity oil fields in Uzbekistan

The results of experimental research on studying the filtration properties of polymer solutions and the mechanism of the displacement process in porous medium were presented in this article. The methodology of experimental studies in a specially designed laboratory setup is given. In the present work the rheological properties of polymer K-9 are considered. At the same time, the relaxation time of viscoelastic particles of K-9 polymer filtered in porous medium is experimentally found. Also, the results of experimental studies on oil displacement of fields with high content of asphaltene-resinous substances by polymer solutions on artificially created reservoir models to determine the optimal concentration of polymer solution and the size of the rim with the purpose of increasing oil recovery. Experimental studies on displacement of high-viscosity oils with a thickened water rim established that this method gives the greatest increase in water-free and ultimate oil recovery of reservoirs, within the range of change in the concentration of polymer solution 0.2-0.4%, with the size of the rim more than 70% of the oil saturated volume of the reservoir. Studies on displacement of high-viscosity oils by polymer solutions show that the use of this method of increasing oil recovery factor in practice is not always economically feasible, because of the need to ensure high injection pressures and high concentration of expensive polymer solution.

Impact of water content on minimum miscibility pressure during CO2 flooding in high water-cut reservoirs

This study focused on the X block stratum oil, specifically addressing the application of CO2 displacement technology in enhancing oil recovery under high water content conditions. It systematically investigates the variation of the minimum miscibility pressure (MMP) between CO2 and formation oil at water contents of 0%, 60%, 70%, 80%, and 90%. The research employed slim-tube model simulation experiments and theoretical analysis to explore the impact of different water contents on the physical properties of formation oil and the changes in the interaction mechanism between CO2 and crude oil. The results indicate that the MMP of CO2 flooding is the lowest at 31.11 MPa in the absence of water, reaching the highest value of 37.94 MPa at 90% water content. The MMP of the CO2-formation oil system shows a significant upward trend with increasing water content in the formation, which is related to the stability of the water film, the solubility of CO2, and the interfacial tension between oil and water. Meanwhile, high water content leads to the expansion of formation oil volume, increased viscosity, and compositional changes, collectively influencing the results. This study provides theoretical support for the field application of CO2 flooding and offers critical references for optimizing the oil displacement process.

Numerical study on the characteristics of viscous fingering during the displacement process of non-Newtonian fluid.

This study uses numerical methods (ANSYS-Fluent) to investigate the viscous fingering of the displaced phase as a shear-thinning fluid in the classic three-dimensional Hele-Shaw cell. Comparing the behavior of fingerings with different properties on the upper and lower surfaces of a three-dimensional model, it was found that when the upper and lower surfaces are walls, under the combined action of moving contact lines and Saffman-Taylor instability, fingering splitting occurs at the tip, resulting in the appearance of two fingers at the interface. In addition, we have found that interfacial tension has a suppressive effect on short waves. As the interfacial tension increases, the velocity at the advancing tip decreases. Therefore, when the interface tension is 0, viscous fingering displacement reaches the farthest distance. We have also conducted research on the viscous fingering at different temperatures. The results indicate that increasing the temperature leads to a decrease in the viscosity of the displaced phase, making the flow more stable. As the temperature rises, the pressure gradient inside the flow path increases, pushing the viscous fingering further.

The Examination of Stuart Hall’s Postcolonial Perspective on Displacement and Identity Discontinuity in Fadia Faqir’s The Cry of the Dove (2007).

Displacement is a key concept in postcolonial Diaspora literature that interprets the transition from the motherland, native culture, traditions, and native language to a different setting. Such geographical, cultural and psychological transitions result in an identity crisis, fragmentation and discontinuity. The objective of this study is to investigate, in Fadia Faqir's The Cry of the Dove, the process of identity development amid displacement of a female Arab Muslim in a postcolonial setting. Using Stuart Hall's theory of Cultural Identity and Diaspora, this article applies a postmodern reading on the novel to discern how displacement affects the identity of the main protagonist Salma. Hence, Salma experiences a series of encounters following her transition from her original space to a new one that results in an identity crisis characterised by fragmentation, sense of alienation and uncertainty. In a postmodernist Stuart Hallian sense, Fadia Faqir’s female protagonist suffers from an existentialist, discontinuous identity characterized by skepticism, uncertainty, fragmentation and paradox, following a journey of physical and psychological displacement.

Forecast of technological indicators for the implementation of carbon dioxide injection in conditions of depleted deposits of the Ural-Volga region

This article presents the results of theoretical studies of the mechanism of the effect of CO₂ on residual oil in depleted fields. The task of studying the filtration processes of gas-liquid mixtures has been solved using mathematical modeling. A hydrodynamic model of the process of oil displacement by carbon dioxide is proposed, from which, under certain assumptions, equations describing various mechanisms of displacement can be obtained. In addition, methods for calculating the process of flooding of reservoirs with the use of carbon dioxide are considered. Using the example of a landfill site of one of the Ural-Volga deposits, the forecast technological efficiency of using carbon dioxide to increase oil recovery is calculated. Keywords: efficiency improvement; modeling; oil displacement; injection; carbon dioxide; oil recovery.

Mathematical model of the hydrocarbon displacement process by water in zonally heterogeneous deformable reservoirs

The problem of displacing hydrocarbon systems injected into the reservoir by water in zonally heterogeneous collectors is considered. In this case, the reservoir of circular shape, developed by a single central well, is assumed to consist of two zones with different reservoir and rheological properties. The solution to the problem is obtained, taking into account the incomplete displacement, compressibility of water, and PVT properties of the hydrocarbon system—phase transformation, mass exchange between phases of the hydrocarbon system. Based on the binary representation of the complex hydrocarbon system, a solution to the considered problem is obtained, and an algorithm for calculating the main indicators of the hydrocarbon displacement process to the well is proposed. This algorithm accounts for the fact that the reservoir has different reservoir and rheological characteristics in the near-wellbore region (internal zone) and the distant part of the reservoir (i.e., in the external zone). Keywords: Displacement; Gas-condensate mixture; Volatile oil; Heterogeneous reservoir; Water flooding; Binary model; Unsteady-state flow.

Trapping Charge Mechanism in Hv1 Channels (CiHv1).

The majority of voltage-gated ion channels contain a defined voltage-sensing domain and a pore domain composed of highly conserved amino acid residues that confer electrical excitability via electromechanical coupling. In this sense, the voltage-gated proton channel (Hv1) is a unique protein in that voltage-sensing, proton permeation and pH-dependent modulation involve the same structural region. In fact, these processes synergistically work in concert, and it is difficult to separate them. To investigate the process of Hv1 voltage sensor trapping, we follow voltage-sensor movements directly by leveraging mutations that enable the measurement of Hv1 channel gating currents. We uncover that the process of voltage sensor displacement is due to two driving forces. The first reveals that mutations in the selectivity filter (D160) located in the S1 transmembrane interact with the voltage sensor. More hydrophobic amino acids increase the energy barrier for voltage sensor activation. On the other hand, the effect of positive charges near position 264 promotes the formation of salt bridges between the arginines of the voltage sensor domain, achieving a stable conformation over time. Our results suggest that the activation of the Hv1 voltage sensor is governed by electrostatic-hydrophobic interactions, and S4 arginines, N264 and selectivity filter (D160) are essential in the Ciona-Hv1 to understand the trapping of the voltage sensor.

Pulse Electrodeposition in the Presence of Corrosion Reactions during the Off-Time

Pulse electrodeposition of metals and alloys offers one route to enhance or tune material properties. However, an often-neglected period during pulse plating is the off-time, which may also influence deposit properties. Traditionally it is considered a relatively unimportant, allowing, for example, relaxation of concentration gradients, desorption of additives, recrystallization and discharge of the double later capacitance. Over the past few decades, however, studies have shown that it is possible to have ‘internal current’ processes occurring in the off-time which can strongly influence the deposit properties and composition. For example, in the pulse electrodeposition of binary alloys from aqueous solutions, displacement (corrosion) reactions have been observed in the off-time that can significantly alter the alloy composition. This has also been observed in many aqueous and molten salt systems, and appears a very general phenomenon. More recently we have observed corrosion arising from a comproportionation reactions during the pulse plating of copper from a deep eutectic solvent (DES) and noted some of their effect on deposit properties.The main purpose of this paper is to examine some of the similarities and differences in off-time corrosion caused by displacement and comproportionation processes during pulse electrodeposition. As is shown in the figure, corrosion may occur due to the presence of oxygen, or due the presence of a noble material leading to displacement reactions, as well as the presence of a stable species of differing valency in solution leading to comproportionation reactions. These differing mechanisms can produce different effects on the deposit. We will discuss how these different mechanisms can be understood and the influence on the deposit and their characteristics. Figure 1

DEM analysis of the effect of geocell on splitting tensile behavior of asphalt mixture based on multi-phase model

Herein, an investigation was conducted upon the reinforcement of geocell on the splitting tensile process of asphalt mixture using laboratory tests and the discrete element method (DEM). Micromechanical modeling of geocell-reinforced asphalt mixture and virtual splitting tensile test was built using PFC3D based on the vital material features and mechanical properties of different ingredients (e.g., the three-dimensional irregular shapes and elastic properties of coarse aggregates and geocell, the viscoelastic properties of asphalt mastic, and the random distribution of air voids in asphalt mastic). Meanwhile, the parameters of the DE model were determined by splitting tensile test, and the effects of geocell on the splitting tensile process of contact force, displacement and stress were evaluated through the virtual splitting test. The results indicated the efficiency of the built DE model and virtual test in effectively predicting the splitting process of geocell-reinforced asphalt mixture. Besides, geocell acted mainly in the falling stage of the load-displacement curve during the splitting process, where the contact force distribution of each phase component shifted from the lower to the higher range, and the effect between coarse aggregates was the greatest, followed between coarse aggregate and asphalt mastic, with the least within asphalt mastic. Further, the maximum displacement of asphalt mixture in the X and Y directions was reduced by the geocell, significantly constraining the coarse aggregate and mastic in geocell-reinforced layer. In addition, the stress in the splitting center of asphalt mixture was greater than that at the sides, and the stress within the geocell of the reinforced layer was significantly lower compared to the unreinforced layer, especially in the falling stage. Overall, the present results forge a theoretical basis for the tensile performance of geocell-reinforced asphalt mixture from the microscopical perspective.

A new interacting capillary bundle model on the multiphase flow in micropores of tight rocks

Surfactants are widely used in the fracturing fluid to enhance the imbibition and thus the oil recovery rate. However, current numerical models cannot capture the physics behind capillary imbibition during the wettability alteration by surfactants. Although the interacting capillary bundle (ICB) model shows potential in characterizing imbibition rates in different pores during wettability alteration, the existing ICB models neglect the influence of wettability and viscosity ratio on the imbibition behavior, making it difficult to accurately describe the oil–water imbibition behavior within the porous media. In this work, a new ICB mathematical model is established by introducing pressure balance without assuming the position of the leading front to comprehensively describe the imbibition behavior in a porous medium under different conditions, including gas–liquid spontaneous imbibition and oil–water imbibition. When the pore size distribution of a tight rock is known, this new model can predict the changes of water saturation during the displacement process in the tight rock, and also determine the imbibition rate in pores of different sizes. The water saturation profiles obtained from the new model are validated against the waterflooding simulation results from the CMG, while the imbibition rates calculated by the model are validated against the experimental observations of gas–liquid spontaneous imbibition. The good match above indicates the newly proposed model can show the water saturation profile at a macroscopic scale while capture the underlying physics of the multiphase flow in a porous medium at a microscopic scale. Simulation results obtained from this model indicate that both wettability and viscosity ratio can affect the sequence of fluid imbibition into pores of different sizes during the multiphase flow, where less-viscous wetting fluid is preferentially imbibed into larger pores while more-viscous wetting fluid tends to be imbibed into smaller pores. Furthermore, this model provides an avenue to calculate the imbibition rate in pores of different sizes during wettability alteration and capture the non-Darcy effect in micro- and nano-scale pores.

Trends in population mobility in the constituent entities of the Central Federal District

Subject. This article discusses the problems of employment, migration policy of Russia and spatial development of the country. Objectives. The article aims to analyze the processes of displacement of the urban and rural population of the Orel Oblast and the Central Federal District, as well as rank the regions of the Central Federal District by level of economic development. Methods. For the study, we used a statistical analysis. Results. Based on the analysis of the absolute indicators of migration of the urban and rural population of the region, the article determines the factors of population decline in the Orel Oblast and the direction of people's movement. Conclusions. State migration policy should be aimed at reducing interregional migration. This goal can be achieved by reducing the differentiation of regions according to the level of socio-economic development.

The Time-Varying Variation Characteristics of Methane during Nitrogen Injection Process: An Experimental Study on Bituminous Coals

The existing research on CH4 displacement by N2 mainly focuses on the gas injection displacement mechanism and the factors affecting displacement efficiency. And most of them are theoretical analyses at the model level or multifactor analyses at the simulation test level, while there are few targeted physical simulation tests and quantitative analyses. Given the above problems, the experiment system was used to study the gas migration evolution law and time-varying characteristics of CH4 displacement by N2 in coal under different injection pressures. The experimental results show that the whole process of CH4 displacement by N2 can be divided into three stages: stage I (original equilibrium stage); stage II (dynamic balance stage); stage III (new equilibrium stage). The concentration of CH4 and N2 presents an opposite variation trend, and the variation rate of CH4 and N2 increased first and then decreased. The breakthrough time was 50 minutes, 45 minutes, 35 minutes, 25 minutes, and 20 minutes, respectively, under different injection pressures. The displacement efficiency increased with the injection pressures, while the replacement ratio decreased with the injection pressures. The maximum flow rate of CH4 was 0.085 mL/min, 0.110 mL/min, 0.130 mL/min, 0.222 mL/min, and 0.273 mL/min, respectively, under different injection pressures. The accumulated production of CH4 was 3.59 mL, 3.91 mL, 4.39 mL, 5.58 mL, and 5.94 mL, respectively, under different injection pressures. The effective injection pressure range was 1.6~2 MPa. This research can provide a reference for the theoretical research of N2-ECBM-related technology in low permeability reservoirs and the selection of injection pressure in the field technology implementation.

Effect of CO2 injection on the gas desorption and diffusion kinetics: An experimental study

During CO2 displacement, the diffusion characteristics of gas in the coal matrix are among the key factors that affect the gas extraction rate, and discussed the influence mechanism of CO2 injection on the diffusion kinetics of coal seam gas. In this study, we used a self-developed CO2–CH4 displacement experimental platform to study the diffusion characteristics of CH4 under different CO2 injection pressures and temperatures. As the CO2 injection pressure was increased from 0.6 MPa to 1.0 MPa, the CH4 production increased by 9.44 %, the CH4 maximum diffusivity increased by 0.05, the effective diffusion coefficient extreme point increased by 111.45 %. As the gas injection temperature was increased from 40 °C to 60 °C, the CH4 production increased by 4.02 %, the CH4 maximum diffusivity increased by 0.03, the maximum of the effective diffusion coefficient increased by 103.31 %. To better explain the gas diffusion characteristics during CO2 displacement, the influence mechanism of increasing CO2 injection pressure and temperature on the CH4 diffusion kinetics was discussed, and the driving force (fd) and resistance (fr) during the displacement process were studied. The dynamic CO2 injection models were considered to be more effective in ensuring efficient CH4 recovery.

Self-Assembly of Designed Peptides with DNA to Accelerate the DNA Strand Displacement Process for Dynamic Regulation of DNAzymes.

Toehold-mediated DNA strand displacement (TMSD) is a powerful tool for controlling DNA-based molecular reactions and devices. However, the slow kinetics of TMSD reactions often limit their efficiency and practical applications. Inspired by the chemical structures of natural DNA-operating enzymes (e.g., helicase), we designed lysine-rich peptides to self-assemble with DNA-based systems. Our approach allows for accelerating the TMSD reactions, even during multiple displacement events, enhancing their overall efficiency and utility. We found that the acceleration is dependent on the peptide's sequence, length, and concentration as well as the length of the DNA toehold domain. Molecular dynamics simulations revealed that the peptides promote toehold binding between the double-stranded target and the single-stranded invader, thereby facilitating strand displacement. Furthermore, we integrated our approach into a horseradish peroxidase-mimicking DNAzyme, enabling the dynamic modulation of enzymatic functions on and off. We anticipate that the established acceleration of strand displacement reactions and the modulation of enzymatic activities offer enhanced functionality and control in the design of programmable DNA-based nanodevices.

A non-contact vehicle weighing approach based on bridge weigh-in-motion framework and computer vision techniques

Bridge weigh-in-motion (BWIM) system plays increasingly important role in vehicle load monitoring and bridge maintenance due to advantages of high efficiency and little impact on traffic. However, the contact-type sensors in a traditional BWIM system should be installed in advance and is environment-sensitive, which hinders its application. To this end, a vision-based contactless BWIM (cBWIM) system is proposed. The core idea of the current method is to replace the traditional contact-type sensors by two consumer cameras to realize real-time monitoring of bridge displacement and vehicle trajectory. The cBWIM system consists of three modules, including the axle weight identification algorithm, the bridge displacement monitoring system and the vehicle trajectory tracking system. The influence line-based Moses algorithm is utilized for identification of axle weight. For bridge displacement monitoring, the minimum bounding rectangle-based similarity matching method is proposed to achieve high accuracy measurement of displacement and real-time data processing. For vehicle trajectory tracking, a deep learning-based YOLOv5s algorithm is adopted as a detector, combined with DeepSort algorithm to realize real-time tracking of vehicle position. The cBWIM system is applicable for non-uniform motion and vehicle occlusion cases. Laboratory tests covering various cases (i.e. uniform motion, non-uniform motion and visual occlusion) and field measurement on a full-scale bridge have demonstrated that the proposed method is effective and reliable and can provide alternative tool to the current vehicle weighing methods.

Effects of cosolvents on CO2 displacement of shale oil and carbon storage

Molecular dynamics method was used to establish composite wall/inorganic nanopores of three pore sizes, three shale oil systems, five CO2-cosolvent systems, and pure CO2 system. The process of CO2-cosolvent displacement of crude oil in shale nanopores and carbon storage was simulated and the influencing factors of displacement and storage were analyzed. It is shown that the attraction of the quartz wall to shale oil increases with the degree of hydroxylation. The higher the degree of quartz hydroxylation, the more difficult it is to extract the polar components of shale oil. Nanopore size also has a great impact on shale oil displacement efficiency. The larger the pore size, the higher the shale oil displacement efficiency. The closer the cosolvent molecules are to the polarity of the shale oil, the higher the mutual solubility of CO2 and shale oil. The more the non-polar components of shale oil, the lower the mutual solubility of CO2 and shale oil with highly polar cosolvent. Ethyl acetate is more effective in stripping relatively high polar shale oil, while dimethyl ether is more effective in stripping relatively low polar shale oil. Kerogen is highly adsorptive, especially to CO2. The CO2 inside the kerogen is not easy to diffuse and leak, thus allowing for a stable carbon storage. The highest CO2 storage rate is observed when dimethyl ether is used as a cosolvent, and the best storage stability is observed when ethyl acetate is used as a cosolvent.

Investigation of the Diffusion of Chloride Ions in Blended Cement Pastes

AbstractWhen exposed to aggressive environments containing chlorides, the chlorine ion partially binds to the usual Portland cement mortar and changes its mineralogy. Chlorine ions entering the system displace sulfate from the monosulfoaluminate. Such systems form Kusel's salt at low chloride concentrations and Friedel's salt at higher concentrations. Unbound chloride ions remain dangerous for reinforcing steel, which diffuse deep into the concrete and destroy the passivating layer on the reinforcement. To assess the protective properties of concrete in relation to metal reinforcement, it is proposed to investigate the process of displacement of the diffusion front in cement composites of various compositions. It is also important to study changes in such characteristics as porosity and filtration properties, which significantly affect the penetration depth of an aggressive medium. The study of the structure, mineral and chemical composition is carried out in layers.

Investigation of the transport and metabolic patterns of oil-displacing bacterium FY-07-G in the microcosm model using X-CT technology.

Microbially Enhanced Oil Recovery (MEOR) is dedicated to enhancing oil recovery by harnessing microbial metabolic activities and their byproducts within reservoir rocks and fluids. Therefore, the investigation of microbial mobility and their extensive distribution within crude oil is of paramount importance in MEOR. While microscale models have been valuable for studying bacterial strain behavior in reservoirs, they are typically limited to 2D representations of porous media, making them inadequate for simulating actual reservoir conditions. Consequently, there is a critical need for 3D models and dependable visualization methods to observe bacterial transport and metabolism within these complex reservoir environments. Bacterial cellulose (bc) is a water-insoluble polysaccharide produced by bacteria that exhibits biocompatibility and biodegradability. It holds significant potential for applications in the field of MEOR as an effective means for selective plugging and spill prevention during oil displacement processes. Conditionally cellulose-producing strain, FY-07-G, with green fluorescent labeling, was engineered for enhanced oil recovery. 3D micro-visualization model was constructed to directly observe the metabolic activities of the target bacterial strain within porous media and to assess the plugging interactions between cellulose and the medium. Additionally, X-ray computed tomography (X-CT) technology was employed for a comprehensive analysis of the transport patterns of the target strain in oil reservoirs with varying permeabilities. The results indicated that FY-07-G, as a microorganism employing biopolymer-based plugging principles to enhance oil recovery, selectively targets and seals regions characterized by lower permeability and smaller pore spaces. This work provided valuable insights into the transport and metabolic behavior of MEOR strains and tackled the limitation of 2D models in faithfully replicating oil reservoir conditions, offering essential theoretical guidance and insights for the further application of oil-displacing bacterial strains in MEOR processes.

Estimation of Capillary‐Associated NAPL‐Water Interfacial Areas for Unconsolidated Porous Media by Kinetic Interface Sensitive (KIS) Tracer Method

AbstractBy employing kinetic interface sensitive (KIS) tracers, we investigate three different types of glass‐bead materials and three natural porous media systems to quantitatively characterize the influence of the porous‐medium grain‐, pore‐size and texture on the specific capillary‐associated interfacial area (FIFA) between an organic liquid and water. By interpreting the breakthrough curves (BTCs) of the reaction product of the KIS tracer hydrolysis, we obtain a relation for the specific IFA and wetting phase saturation. The immiscible displacement process coupled with the reactive tracer transport across the fluid–fluid interface is simulated with a Darcy‐scale numerical model. Linear relations between the specific capillary‐associated FIFA and the inverse mean grain diameter can be established for measurements with glass beads and natural soils. We find that the grain size has minimal effect on the capillary‐associated FIFA for unconsolidated porous media formed by glass beads. Conversely, for unconsolidated porous media formed by natural soils, the capillary‐associated FIFA linearly increases with the inverse mean grain diameter, and it is much larger than that from glass beads. This indicates that the surface roughness and the irregular shape of the grains can cause the capillary‐associated FIFA to increase. The results are also compared with the data collected from literature, measured with high resolution microtomography and partitioning tracer methods. Our study considerably expands the applicability range of the KIS tracers and enhances the confidence in the robustness of the method.

Experimental investigation of laminar and turbulent displacement of residual oil film

Residual oil films on pipe walls are a common occurrence in industrial processes, and their presence can significantly impact system efficiency and performance. However, the mechanisms that govern oil film removal by an immiscible displacing fluid from the internal walls of pipes under different flow regimes, including laminar and turbulent flows, are not yet fully understood. In this study, we investigated the impact of displacing fluid flow regime, injected volume, displacement time, and wall shear stress on the efficiency of residual oil film removal in a pipe. We first verified the applicability of our developed oil film measurement method for the use in vertical pipes, and found that gravity did not significantly affect the long-term oil film removal process. We verified that our results from the laminar cases agree with the theoretical thin-film limit scaling under reasonable assumptions of constant shear stress and negligible surface tension. We then examined the displacement efficiency of residual oil film under laminar and turbulent flow regimes. Our experimental results revealed that the onset of turbulence of displacing fluid played an important role in the efficient removal of residual oil film, with an optimal range of Reynolds numbers (7000–8000) when the injected volume of displacing fluid is limited. Furthermore, we explored the combined effect of wall shear stress and displacement time on the displacement process under different turbulent flow regimes. We found that the intermediate turbulent regime was the most efficient for achieving cleaning in a limited time, while the highly turbulent regime proved to be the most effective for achieving complete cleaning over a longer time period. These findings have important implications for oil recovery and pipeline maintenance and provide valuable insights into optimizing the removal of residual oil film in pipes.