Displacement Process Research Articles

The influence of low-permeability geological inclusions on the seepage behavior of ionic rare earth leaching mining: A study using visual microfluidic technology

Ionic rare earth deposits often contain semi-weathered or slightly weathered low-permeability geological inclusions (LPGI), which significantly impact the permeation process and leaching efficiency of in-situ liquid leaching mining. To investigate the influence of LPGI with varying developmental degrees on the seepage process of ionic rare earth leaching mining, we developed six microfluidic chip models using Polydimethylsiloxane (PDMS). A visual experiment was conducted, employing water to drive gas at a rate of 0.5 μl/min, enabling observation of the seepage and displacement process. Using MATLAB image processing technology in conjunction with time-history diagrams, we analyzed the evolution patterns of the infiltration front position and saturation over time. Our findings revealed distinct capillary fingering and side wall flow phenomena during the process of liquid phase displacing gas phase infiltration, accompanied by horizontal and counter flows perpendicular to the solution's direction of advancement. Notably, when the solution traversed the LPGI, we observed significant flow-around phenomena and low saturation of the LPGI. These inclusions hindered solution infiltration, with wider LPGI resulting in greater inhibition. Additionally, the LPGI acted as a protective barrier, preventing solution intrusion into the underlying ore body. However, due to the air discharge is not timely, it was sealed by the outlet solution, forming a substantial leaching blind area near the outlet. This study unveils the seepage laws of ionic rare earth earth leaching mining involving LPGI of various developmental degrees, signifying its vital engineering significance in the efficient extraction of ionic rare earth.

Displacement through the Commons: Community and Spatial Order in Bangkok

AbstractThis article investigates the relationship of discourses around community to larger urban processes of development and displacement in Bangkok, Thailand. It focuses on two sites located along a major commercial corridor. The first, undergoing a process of relocation that involves establishing collective land tenure, goes by the Thai term for community, chumchon, though architects and planners frequently refer to it as a “slum.” The second site, an upscale “community mall” called the Commons, is a newly constructed open‐air commercial space built to serve Bangkok's young, hip creative class. The eviction of the poor chumchon residents in favor of wealthy café‐goers may look like a prime example of larger structural forces of what is often called “gentrification” or “accumulation by dispossession.” However, these sweeping narratives around global capitalist processes miss critical aspects of how the discursive construction of community around these two sites has enabled their physical construction and deconstruction. We demonstrate that rhetorics, imagery, and practices of community serve to valorize the existence of one site while justifying the removal of the other. This analysis demonstrates this outcome was not just the inevitable result of impersonal structural forces. It was displacement through the commons, fueled by discourses around community.

Primary cementing of vertical wells: displacement and dispersion effects in narrow eccentric annuli. Part 2. Flow behaviour and classification

We present results for Newtonian laminar miscible displacement flows in a narrow, vertical, eccentric annulus, obtained from experiments carried out in a scaled laboratory set-up. These are compared with two computational models introduced in Part 1, Zhang & Frigaard (J. Fluid Mech., vol. 947, 2022, A732). Quite close matches have been found for different approaches, regarding the overall evolving displacement process: front shape, dispersion levels and front velocities. Standardized criteria have been established to identify whether a flow has steady/unsteady and dispersive/non-dispersive displacement front, applicable to both concentric and eccentric annuli. Three characteristic flows have been observed, unsteady and dispersive, dispersive with steady front, and non-dispersive with steady front. Through both qualitative and quantitative studies, the importance of the buoyancy number has been established: it both restrains dispersion on the annular gap scale and induces secondary flows in the azimuthal direction.

Rio 2016 Olympic Games: the Process of Eviction and Resistance of Vila Autodromo's Residents

Working-class evictions and displacements have been documented for several Olympic Games, pointing to the role of the International Olympic Committee in contributing to an increase in human rights violations. This article aims to report and to discuss an eviction process carried out by the government of the city of Rio de Janeiro during the preparations of the 2016 Olympic Games. The focus is on the community of workers from Vila Autodromo (Barra da Tijuca), who endured a long process of displacements between 2009 and 2016 and is, to date, the only worldwide documented community that has resisted a displacement process during an Olympic Games. Interviews conducted with Vila Autodromo's residents and supporters lead to the conclusion that the Games were used as a mechanism for major infrastructural changes in Barra da Tijuca to increase the land values for private gains.

Engineering method for predicting the displacement of the earth’s surface under the influence of stope workings of coal mines

The development of a sufficiently reliable forecast of the values of trough parameters on the earth’s surface and the displacement of undermined rocks using mathematical modeling methods is an urgent problem for mining. Not only the protection of objects on the earth’s surface depends on its successful solution, but also the choice of the location of mine workings and rational ways to protect them from the influence of rock pressure, the forecast of gas release from undermined sources, the occurrence of gas-dynamic phenomena, the rationale for rational ventilation schemes for excavation areas, the calculation of the bearing capacity supports and many other engineering tasks. The study is based on the use of experimental data obtained during the operation of a separate extraction area, respectively, at the first stage when the working face is removed from the split furnace and at the second stage above the working face when it is sufficiently removed from the open working. This makes it possible to obtain all the necessary experimental data for constructing a general scheme for the development of clearing operations and the formation of a trough for the displacement of the earth’s surface in two stages. On the basis of the studies carried out, it was found that the maximum subsidence of the earth’s surface above the cut working with a sufficient distance from the production face is equal to the subsidence above the production face at the stage of attenuation of the processes of displacement of undermined rocks and the earth’s surface. This gives grounds to make an assumption about the closeness of the displacement parameters of the stationary and dynamic semitroughs.

Wettability modification effects on relative permeability end-points: Comparative analysis of surfactant agents for enhanced oil recovery

This research examines the impact of wettability alteration on the end points of relative permeability, a crucial property of fluids and porous media that influences the displacement processes of immiscible fluids through such media. The estimation of the mobility ratio for oil recovery relies on these end points, which are influenced by connate water saturation and residual oil saturation. To investigate this relationship, carbonate rock is generally subjected to wettability alteration using surfactant agents, and core flooding is employed to determine the relative permeability before and after the alteration. The wettability of the rock is commonly assessed through contact angle measurements. Two surfactants, TritonX-100 (Tx-100) and Cedar, were tested in reducing the wettability of the porous media for oil. The contact angle measurements revealed that Tx-100 was more effective for this purpose than Cedar. Furthermore, the relative permeability tests indicated that both surfactants decreased residual oil saturation, but Tx-100 also improved system pressure. In contrast, Cedar reduced residual oil saturation but increased system pressure, possibly because of its high viscosity. The results also demonstrate that injecting Tx-100 leads to a 14% increase in ultimate oil recovery compared with water injection, while Cedar injection increased the recovery factor by 5%. This difference may be attributed to the incomplete coverage of the pore wall by Cedar or its weaker chemical structure than Tx-100. Notably, in carbonate cores, neither non-ionic surfactant enhanced oil recovery.

Rapid mechanosensitive migration and dispersal of newly divided mesenchymal cells aid their recruitment into dermal condensates.

Embryonic mesenchymal cells are dispersed within an extracellular matrix but can coalesce to form condensates with key developmental roles. Cells within condensates undergo fate and morphological changes and induce cell fate changes in nearby epithelia to produce structures including hair follicles, feathers, or intestinal villi. Here, by imaging mouse and chicken embryonic skin, we find that mesenchymal cells undergo much of their dispersal in early interphase, in a stereotyped process of displacement driven by 3 hours of rapid and persistent migration followed by a long period of low motility. The cell division plane and the elevated migration speed and persistence of newly born mesenchymal cells are mechanosensitive, aligning with tissue tension, and are reliant on active WNT secretion. This behaviour disperses mesenchymal cells and allows daughters of recent divisions to travel long distances to enter dermal condensates, demonstrating an unanticipated effect of cell cycle subphase on core mesenchymal behaviour.

Integral Effects of Porosity, Permeability, and Wettability on Oil–Water Displacement in Low-Permeability Sandstone Reservoirs—Insights from X-ray CT-Monitored Core Flooding Experiments

Porosity, permeability, and wettability are crucial factors that affect the oil–water displacement process in reservoirs. Under subsurface conditions, the integral effects of these factors are extremely difficult to document. In this paper, waterflooding experiments were carried out using a core flooding system monitored with X-ray dual-energy CT. The mesoscale, three-dimensional characteristics of water displacing oil were obtained in real time. The integral effects of porosity, permeability, and wettability on the waterflooding in the low-permeability sandstone reservoirs were investigated. It was found that if the reservoir rock is water-wet, then the residual oil saturation decreases gradually with increasing porosity and permeability, showing an increasing waterflooding efficiency. On the contrary, if the reservoir rock is oil-wet, the residual oil saturation gradually increases with improving porosity and permeability, showing a decreasing waterflooding efficiency. The porosity, permeability, and wettability characteristics of reservoirs should be comprehensively evaluated before adopting technical countermeasures of waterflooding or wettability modification during oilfield development. If the porosity and permeability of the reservoir are high, water-wet reservoirs can be directly developed with waterflooding. However, it is better to make wettability modifications first before the waterflooding for oil-wet reservoirs. If the porosity and permeability of the reservoir are poor, direct waterflooding development has a better effect on oil-wet reservoirs compared with the water-wet reservoirs.

Magnetoelastic Losses in the Linear Response Region for Three- and Four-Axis Idealized Magnets

In the presented studies, a description of the losses related to relaxation processes in idealized three- and four-axis ferromagnets, as well as ferrites, is considered for the case of a linear response (small perturbations) on the basis of a macroscopic approach. The description takes into account reversible 90° displacements of domain walls (DW) of concentrations (с), ways of DW pinning by linear defects, and processes of DW displacements and rotations of the spontaneous magnetization vector I⃗s, caused by a longitudinal elastic stress wave σ. As a result, the anisotropy of amplitude-independent losses emerges due to displacement processes. Frequency dependence of losses is obtained with consideration of the magnetic symmetry of the crystal, its magnetostructural parameters, and the concentration of magnetic phases ci. The paper also describes the internal frictionn Q-1, the absorption coefficient a, the velocity of propagation of elastic vibrations v and the Δ (1/E)-effect, thus allowing to reveal the texture in the distribution of DWs by their types.
 It is shown that if the relaxation times of rotation processes τ = β / 2K1 and displacement processes τc = βс / mω20 are the same, then the maxima of the dependence of internal friction on frequency Qc-1(ω) and QB-1(ω) superimpose on each other.
 The revealed features of magneto-elastic energy dissipation are of interest for laboratory studies and have promising applications in practice for determining the orientation of crystals, describing the texture, and calculating the differential ΔЕ-effect in magnets. The features of the ΔЕ-effect for the considered cases are also revealed.

Narrative re/defining of the cultural identity of Bosnia and Herzegovina in the literature of the Bosnia and Herzegovina diaspora

Starting from the hypothesis that spatial-cultural displacement necessarily conditions the deconstruction of cultural identity, the work, based on the theoretical assumptions of imagology and intercultural hermeneutics, considers (inter)cultural aspects of the narrative de/construction of the cultural identity of Bosnia and Herzegovina in the literature of the Bosnian diaspora. Finding examples in the novels "The Book of My Lives" and "My Parents: An Introduction" by Aleksandar Hemon, the novel "Nowhere, out of nowhere" by Bekim Sejranović and the collection of stories "Well, to start over" by Cecilija Toskić, the work tries to point out the spatial-cultural displacement and intercultural processes not only as factors of crosscultural adaptation, acculturation and assimilation, but also as factors that enable objective perception and narrative representation of Bosnian cultural identity. The paper concludes that the experience of spatialcultural displacement, represented in the above-mentioned works, results in the narrative construction of hybrid identities squeezed between two (or more) cultures, and that precisely this position of (non)belonging will enable a narrative re/definition of the cultural identity of Bosnia and Herzegovina.

Reversing displacement: Navigating the spontaneity of spatial networks of craft, tradition and memory in post-war Old Mosul

The destruction of Mosul's Old Town has led to sudden and unmanaged displacements of different ethnic, cultural and professional communities who departed northern Iraq's medieval trade and cultural centre. While the reconstruction of historic monuments was prioritised for the post-ISIS recovery process, the disappearance of trade, culture, and communities had a more lasting impact on the erasure of memory, traditional practices and social interactions in the Historic Centre. Moving away from the conventions of planned and structured return in post-conflict cities, this paper investigates the growing and unstructured spontaneous processes of displacement, relocation, and rebuilding as an unmanaged process where the central government and the local authority had limited impact on the daily and active return of displaced communities and craftsmen. We argue that the active and interconnected networks of trade, craft communities and livelihoods in the Old City can be activated by individualistic efforts to trigger a spontaneous, yet effective and decentralised approach to post-conflict return in Iraq. This paper navigates local narratives, spaces of memory and spatial patterns of displacement and return, using the observations, spatial mapping, first-hand local narratives and flows of displacement.

Study of Fluid Displacement Processes and Sequestration of CO2 in Coal Reservoirs Using Nuclear Magnetic Resonance Spectroscopy

Study of Fluid Displacement Processes and Sequestration of CO2 in Coal Reservoirs Using Nuclear Magnetic Resonance Spectroscopy

Pore-scale mechanisms and hysteresis effect during multi-cycle injection and production process in underground hydrogen storage reservoir

Injection and production of hydrogen gas storage through multiple cycles often lead to significant variations in the gas water occurrence state and the associated relative permeability curve (RPC). In this study, a visual sandstone etching model and numerical simulation method are used to analyze the alteration of the occurrence state after multiple cycles of gas-water inter drive. The influence of the occurrence state on the variation of the RPC is revealed. The experimental results demonstrate that with an increasing number of cyclic injection and production cycles, the gas saturation in the model shows an upward trend, rising from 64.26% to 73.89%. However, the water block phenomenon also increases, leading to only a small amount of gas bubbles undergoing discrete flow, resulting in a reduction of the porosity utilization from 51.06 % to 40.57 %. In different injection and production cycles, the liquid phase at the corners and blind ends of large pores is difficult to displace. The continuity of gas-liquid distribution enhances with the increase in injection and production cycles. The phenomenon of phase trapping during hydrogen multi-cycle injection is evident, and the relative permeability of the gas phase rapidly declines during the imbibition first stage. The difference in gas saturation between the displacement and imbibition processes gradually decreases, reducing from 0.314 to 0.054. The Carlson model achieves a final simulation accuracy of over 90 % for wettability hysteresis. The numerical simulation results indicate that the modified relative permeability curves can more accurately simulate the changes in hydrogen gas storage during injection and production. The relative error of the hydrogen saturation in the uppermost layer of the reservoir at 1673 days of operation is 8.51 %. And the pressure increase is 13.32% without considering the wetting hysteresis model.

Experimental Study on Multi-Dimensional Visualization Simulation of Gas and Gel Foam Flooding in Fractured-Vuggy Reservoirs.

Gas flooding and foam flooding are potential technologies for tertiary oil recovery in fractured-vuggy reservoirs. The development and mechanism research of fractured-vuggy reservoirs is difficult due to the complex structures and the strong heterogeneity of fractured-vuggy reservoirs. Visualization simulation is one of the effective methods to study the flow behavior of fluid in fractured-vuggy reservoirs. In this study, an upscaling method of visualization simulation from one dimension (1D) to three dimensions (3D) was established, and the physical models of fractured-vuggy reservoirs were designed and fabricated. Water flooding, gas flooding, and gel foam flooding were carried out in the models. The experimental results showed that gas flooding has a single flow channel and water flooding has multiple flow channels in fractures and vugs. Gel foam with an excellent capability of mobility control and a high microscopic displacement efficiency swept in all directions at a uniform velocity. The EOR mechanisms of gel foam in fractured-vuggy reservoirs were mainly as follows: reducing interfacial tension, increasing mobility ratio, selectively plugging high permeability channels, and discontinuous flow. In the displacement process of fractured-vuggy reservoirs, water should be injected from the well at the bottom of the reservoir, and gas should be injected from the well located in the vug at the high part of the reservoir. Gel foam with strong stability and high viscosity should be selected and injected in most kinds of injection wells in fractured-vuggy reservoirs. This study provides a complete method of visualization simulation for the study of flow behavior in fractured-vuggy reservoirs and provides theoretical support for the application of gas flooding and gel foam flooding in fractured-vuggy reservoirs.

A redox-active dual-network hydrogel electrolyte for flexible supercapacitor

In recent years, the research focus of flexible supercapacitor is to improve its energy density. The recently reported improved energy storage method is to introducing suitable redox-additive in gel electrolytes to enhance their redox-activity. Herein, a novel stretchable, redox-active and double-network 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxy-containing polyacrylamide/alginate/H2SO4 (PAM/SA/H2SO4/TEMPOL) hydrogel electrolyte is prepared by radical cross-linking polymerization and solvent displacement process. The PAM/SA/H2SO4/TEMPOL hydrogel possesses superior stretchability (750 %) because of the electrostatic interactions between the -NH3+ groups of the PAM and the -COO− groups of SA. In addition, the introduction of the TEMPOL additive into PAM/SA/H2SO4/TEMPOL hydrogel electrolyte of flexible EDLC can gain a high specific capacitance (386 F g−1) and high energy density of 24.5 Wh kg−1, which is due to dual redox reactions both positive/negative electrode. This study provides a new strategy for designing a multifunctional redox hydrogel electrolyte.

Modeling pore-scale CO2 plume migration with a hypergravity model

Understanding site-scale carbon dioxide migration in saline aquifers is crucial for storage safety. High time and economic costs make establishing a full-scale model of this long-term and large-scale process difficult. Hypergravity model shortens the length and time scale, which has been applied to physical modeling of two-phase immiscible displacement. To evaluate the feasibility of hypergravity modeling two-phase displacement in porous media at pore scale, CO2 migration in saline aquifer is a suitable and classic problem. We used the phase field method to simulate the vertical displacement of brine by carbon dioxide due to buoyancy and pressure at the pore scale. The pore-scale phenomena of the two-phase displacement process were obtained by assessing different flow rates with or without gravity. We systematically analyzed the feasibility of the hypergravity model to evaluate CO2 migration in the geological domain by evaluating the hypergravity effect and using dimensionless analysis. We provide suggestions for performing the hypergravity model to evaluate and predict immiscible displacement in two-phase system.

Interfacial dilatational rheology and displacement mechanism of nano‐flooding system

AbstractIn the field of crude oil extraction, nano‐flooding technology can significantly improve the oil displacement efficiency and provide important technical support for tertiary oil recovery. Although a host of studies have been carried out in this domain, its dilatational rheology and displacement mechanism are rarely reported. In order to address this gap in the extant literature, as a crucial component of this investigation, the interfacial rheology of the nano‐flooding system and the simulated crude oil was systematically studied with the aid of the JMP2000A interface expansion rheometer. Meanwhile, a micro‐displacement experiment was carried out to elucidate its displacement mechanism. The obtained results show that the nano‐flooding system initially increases as its concentration, solution pH, and aging time increase, after which a decline is observed. However, with the change of salinity, it shows a trend of increasing first and then decreasing. Moreover, according to the multi‐factor test results yielded by the relevant software, the relative error is less than 5%, which fully meets the needs of the field and provides an important basis for the field construction. The findings further suggest that the modulus between the nano‐flooding system and the simulated crude oil can be increased by 84‐fold (i.e., from 0.9271 to 78.0739 mN/m). In addition, during the displacement process, the fingering phenomenon of the displacement fluid can be reduced via piston‐like displacement. The swept volume also improves the oil washing efficiency of crude oil, demonstrating that the proposed strategy achieves the purpose of enhancing oil recovery.

Housing Vacancy Outlined with Delphi Survey. Contributions of Participatory Research to a Just Transformation Process on Trial

Rising housing prices, associated supply gaps and displacement processes have revived the “housing issue” in Germany. This is particularly true for certain social groups socially marginalized by high competition in the housing market. The participatory action research study “Wohnungsleerstand wandeln!”(WohL) - “Worthy places from un-used spaces” examines the coexistence of housing scarcity and housing abundance in a district of the Munich metropolitan area. The goal is to use a participatory multi-method design, including a two-stage qualitative Delphi Survey, to find tailored solutions for the housing situation in each community. The Delphi method was used to reflect the diversity of perspectives in housing as well as the principles of participatory action research such as participation in research, proximity to the field, and capacity building through mutual learning. In the case of sustainable housing solutions, a group discussion process, in which facts are listed by participants (who remain anonymous) without taking into account local social structures, can lead to conclusions that are not accepted by the community. Hence, this paper explains how a Delphi Survey can be designed as a qualitative element of participatory action research. Therefore, the WohL Study and its qualitative Delphi Survey are presented, followed by a methodological reflection on the findings. It becomes clear that consensus and anonymity have to be balanced with solution sustainability. Criteria like the selection of participants, the process of group discussion as well as data collection and analysis have to be adapted to the specific field to be explored. New, diversity-sensitive and method-based approaches to decision making pave the way for a transformation of housing that must imply “vacancies” are to be (re)used, but also that collective decision-making brings “overlooked” groups “back into play.” Ultimately, the essential prerequisite for managing the transformation is the participation of the people of the community.

Numerical investigations on the installation of dynamically installed anchors with attached mooring line

Dynamically installed anchors (DIAs) are considered to be one of the most efficient mooring solutions for taut mooring systems. During their installation, DIAs are released from a certain height above the seabed and reach high velocities (up to 35 m/s) before impacting the seabed. However, a potential issue with DIA installation is that the anchor may not remain completely vertical during descent, resulting in the anchor impacting the seabed at an oblique angle and a significant reduction in holding capacity. To address this issue, this paper proposes a new numerical model for DIAs with attached mooring lines, which can consider the forces acting on anchors and mooring lines. A total of 176 numerical simulations were conducted under different initial configurations of mooring lines, and 128 simulations were performed, taking into account the influence of the horizontal motion of Anchor Handling Vessels (AHV). By comparing the velocity, embedment depth and tilting angle, possible combinations of the mooring line configurations in situ were back-analyzed. The simulations results show that the presence of the mooring line significantly reduces the final penetration depth of the anchor, and that the proposed installation model accurately simulates the change process of velocity and displacement during installation. Additionally, when DIAs impact the seabed at an inclined state, the tilting angle will increase due to soil resistance on the anchor tip. Finally, the initial state of the DIA at release is influenced by the horizontal motion of the AHV, which can influence the tilting mechanism of the DIA.

(Invited) Kinetics of SWCNT Coating Displacement By ssDNA Depends on SWCNT Structure

Non-covalent hybrids formed by suspending single-wall carbon nanotubes (SWCNTs) in single-stranded DNA (ssDNA) present novel phenomena and suggest potential applications in biomedicine and nanotube sorting. Although the structures of these hybrids have been simulated using molecular dynamics calculations, much more experimental research is needed to understand their properties. In this study, selective interactions between SWCNTs and ssDNA are probed by measuring the kinetics by which ssDNA displaces SDS (sodium dodecyl sulfate) coatings on the nanotube surfaces. We used samples initially suspended in a low concentration of SDS to allow the coating displacement to occur and to suppress formation of free SDS micelles. The displacement process was monitored by time-dependent measurements of SWCNT fluorescence intensities and wavelengths. Our experiments showed very smooth decreases in fluorescence intensity and red-shifts in fluorescence wavelengths during the displacement process. Through a series of measurements, we found that ssDNA sequences with repeated guanine (G) and thymine (T) bases showed systematic patterns in the coating displacement kinetics. One result is that SDS displacement depends strongly on oligo length, with (GT)3 showing an initial rate constant 500 times greater than that of (GT)20. For shorter oligos in the (GT) n series, we observe an inverse dependence of initial rate constant on SWCNT diameter, with SDS displacement from (6,5) more than twice as fast as from (8,7). However, this diameter dependence is not present for (GT) n oligos with n greater than 6. We also find a distinct and systematic dependence of initial rate constant on nanotube chiral angle for (GT)5 and (GT)6. This effect gives a factor of ~3 difference between (9,1) and (6,5) despite their identical diameters. We empirically find these initial rate constants to vary as (SWCNT diameter)-4(cos 3θ)-y with y = -1/2 for (GT)5 and -1 for (GT)6. In addition, the full displacement kinetic traces are well fitted by double exponential kinetics, with rate constants and amplitudes dependent on SWCNT diameter. A two-step kinetic model for the displacement process will be presented to account for these findings.