Porous Media Systems Research Articles

Understanding the role of water evaporation and condensation in applied smoldering systems

Accurately resolving the way energy is stored and transferred is critical to applied smoldering systems in porous media. Water evaporation and condensation are important mechanisms in the energy conservation of smoldering. This is particularly important when significant water presence can affect the potential for self-sustained smoldering as it occurs in a broad range of practical applications. This paper describes a one-dimensional smoldering model considering water phase change. The model was calibrated to a series of wet smoldering experiments of GAC varying initial water saturation from 5 to 20%. The results show that introducing simple calibration constants on the thermal properties of a wet porous medium can accurately predict the transient and spatial resolution of the progression of evaporation, condensation, and smoldering reactions. A sensitivity analysis suggests that wet smoldering could be improved by increasing fuel concentration and injected airflow, which provides practical insights into wet smoldering applications. In addition, the model was applied to establish five characteristic zones for the wet smoldering front: evaporation, condensation, pre-heating, smoldering, and cooling. The evaporation and condensation zones challenge smoldering propagation due to the high water saturation. The pre-heating zone represents the region separating the smoldering front and evaporation zone, which serves as an important dry buffer and requires a minimum thickness (4 mm) to avoid extinction.

A Three-Phase Relative Permeability Model for Heavy Oil Emulsion System

Chemical flooding is important and effective enhanced oil recovery processes are applied to improve the recovery of heavy oil reservoirs. Emulsification occurs during chemical flooding processes, forming an oil-in-water (O/W) emulsion system. In this work, the heavy oil emulsion system is characterized as a three-phase (continuous oil phase, dispersed oil phase, and continuous water phase) system. Based on a capillary tube model, a new relative permeability model is proposed to describe the flow of the emulsion system in porous media quantitatively, considering the physicochemical properties of emulsions and the properties of porous media. A resistance factor is derived in this model to describe the additional resistance to the emulsion flow caused by the interaction between dispersed oil droplets and the pore system. Three dimensionless numbers related to the emulsion porous flow process were proposed and their different effects on the three-phase relative permeability are investigated. To validate the reliability of the proposed model, a one-dimensional O/W emulsion–oil displacement experiment is simulated. The maximum absolute error between the simulated results and experimental data is no more than 10%, and the new model can be used to describe the flow behavior of heavy oil emulsions in porous media.

Sea water freezing modes in a natural convection system

Sea ice is crucial in many natural processes and human activities. Understanding the dynamical couplings between the inception, growth and equilibrium of sea ice and the rich fluid mechanical processes occurring at its interface and interior is of relevance in many domains, ranging from geophysics to marine engineering. Here we investigate experimentally the complete freezing process of water with dissolved salt in a standard natural convection system, i.e. the prototypical Rayleigh–Bénard cell. Due to the presence of a mushy phase, the studied system is considerably more complex than the freezing of fresh water in the same conditions (Wanget al.,Proc. Natl Acad. Sci. USA, vol. 118, issue 10, 2021, e2012870118). We measure the ice thickness and porosity at the dynamical equilibrium state for different initial salinities of the solution and temperature gaps across the cell. These observables are non-trivially related to the controlling parameters of the system as they depend on the heat transport mode across the cell. We identify in the experiments five out of the six possible modes of heat transport. We highlight the occurrence of brine convection through the mushy ice and of penetrative convection in stably stratified liquid underlying the ice. A one-dimensional multi-layer heat flux model built on the known scaling relations of global heat transport in natural convection systems in liquids and porous media is proposed. Given the measured porosity of the ice, it allows us to predict the corresponding ice thickness, in a unified framework.

Rapid formation of bioaggregates and morphology transition to biofilm streamers induced by pore-throat flows

Bioaggregates are condensed porous materials comprising microbes, organic and inorganic matters, and water. They are commonly found in natural and engineered porous media and often cause clogging. Despite their importance, the formation mechanism of bioaggregates in porous media systems is largely unknown. Through microfluidic experiments and direct numerical simulations of fluid flow, we show that the rapid bioaggregation is driven by the interplay of the viscoelastic nature of biomass and hydrodynamic conditions at pore throats. At an early stage, unique flow structures around a pore throat promote the biomass attachment at the throat. Then, the attached biomass fluidizes when the shear stress at the partially clogged pore throat reaches a critical value. After the fluidization, the biomass is displaced and accumulated in the expansion region of throats forming bioaggregates. We further find that such criticality in shear stress triggers morphological changes in bioaggregates from rounded- to streamer-like shapes. This knowledge was used to control the clogging of throats by tuning the flow conditions: When the shear stress at the throat exceeded the critical value, clogging was prevented. The bioaggregation process did not depend on the detailed pore-throat geometry, as we reproduced the same dynamics in various pore-throat geometries. This study demonstrates that pore-throat structures, which are ubiquitous in porous media systems, induce bioaggregation and can lead to abrupt disruptions in flow.

Evolution of Mineral-Accessible Surface Area Induced by Geochemical Reactions

Mineral dissolution and precipitation reactions occur in a wide range of porous media systems, driven by deviations from an equilibrium between solid and fluid phases. Reactions occur at mineral surfaces in contact with reactive fluids or accessible mineral surface areas. These mineral surface areas can be determined using a multiscale imaging approach and have been shown to improve the simulation of mineral reaction rates in porous media compared to other estimates of reactive surface area. As reactions progress, mineral surface area evolves, and reactive transport simulations often use a simplified model assuming spherical grains to estimate mineral surface area evolution. This, however, does not depict the evolution of reactive surfaces in porous media systems with varying mineral accessibility. This work aims to quantitatively assess the evolution of accessible mineral surface area in porous media for a multimineralic system undergoing mineral dissolution reactions induced by acid exposure. Before and after the reaction, accessible mineral surface areas are determined from 2D scanning electron microscopy, and 3D X-ray computed tomography imaging of a sandstone sample. The quantified evolution of accessible surface area is compared to the calculated mineral surface area evolution using current approaches. Results show an overall increase in total surface area due to the reaction; however, individual mineral surface areas may increase or decrease. Variation is observed in mineral surface area values measured from imaging and equations used in models. The evolution of mineral surface area is largely impacted by the total surface area as well as the pore connectivity rather than porosity and volume fraction evolution.

A Modification of the Beavers–Joseph Condition for Arbitrary Flows to the Fluid–porous Interface

Physically consistent coupling conditions at the fluid–porous interface with correctly determined effective parameters are necessary for accurate modeling and simulation of various applications. To describe single-fluid-phase flows in coupled free-flow and porous-medium systems, the Stokes/Darcy equations are typically used together with the conservation of mass across the interface, the balance of normal forces and the Beavers–Joseph condition on the tangential velocity. The latter condition is suitable for flows parallel to the interface but not applicable for arbitrary flow directions. Moreover, the value of the Beavers–Joseph slip coefficient is uncertain. In the literature, it is routinely set equal to one that is not correct for many applications, even if the flow is parallel to the porous layer. In this paper, we reformulate the generalized interface condition on the tangential velocity component, recently developed for arbitrary flows in Stokes/Darcy systems, such that it has the same analytical form as the Beavers–Joseph condition. We compute the effective coefficients appearing in this modified condition using theory of homogenization with boundary layers. We demonstrate that the modified Beavers–Joseph condition is applicable for arbitrary flow directions to the fluid–porous interface. In addition, we propose an efficient two-level numerical algorithm based on simulated annealing to compute the optimal Beavers–Joseph parameter.Article HighlightsA modification of the Beavers–Joseph condition is proposed based on recently developed generalized coupling conditions.The Beavers-Joseph parameter can be found only for unidirectional flows.An efficient numerical algorithm to determine the optimal Beavers-Joseph parameter is developed.

Performance Evaluation of Silica–Graphene Quantum Dots for Enhanced Oil Recovery from Carbonate Reservoirs

Nanomaterials have shown significant performances in enhancing oil recovery by reducing the interfacial tension (IFT) and contact angle (CA) of the rock/crude oil/water system in porous media. This is evaluated by the synergistic impact of silica–graphene quantum dots (Si–GQDs) on IFT reduction and wettability alteration for the purpose of enhancing oil recovery from carbonate reservoirs. The silica–graphene quantum dots (Si–GQDs) were synthesized by combining graphene oxide and silicon oxide nanoparticles (NPs) and characterized using several analytical techniques. Both distilled water and brine, as dispersion media, were used to prepare nanofluids by dispersing the synthesized Si–GQDs at different concentrations from 1000 to 10,000 ppm. The main properties of the nanofluids including pH, density, and conductivity were measured to evaluate their quality and the performance of Si–GQDs. In addition, the prepared nanofluids were used in the measurements of IFT and contact angles at different concentrations of the synthesized Si–GQDs in both types of used water. The obtained results show that the DWN1000 nanofluid formulated from dispersing 1000 ppm Si–GQDs in distilled water enables an additional 14.4% OOIP oil recovery due to a significant reduction in the value of IFT from 28.3 to 9.5 mN m–1, improving rheology behavior and wettability alteration toward a strong water-wet system from 134 to 61° contact angles.

Remediation of Pool Dominated Trichloroethene Source Zones in Heterogeneous Porous Media by Cosmetic Surfactant Flooding

<p>A series of flow-cell experiments were performed to investigate the performance of cosmetic rhamnolipid surfactant flooding on the relationship between source zone mass removal and mass flux reduction for pool-dominated DNAPL TCE source zones in heterogeneous porous media. The results were also compared to those of water-flood control experiments to assess the surfactant enhanced flushing efficacy. The flooding experiments were performed for silica sand and natural calcareous soil representing two different degrees of physical heterogeneity. The result from the flow-cell experiments showed that higher than 97% of TCE mass was removed during rhamnolipid flooding for both porous media scenarios. Although, rhamnolipid flooding experiment results showed successful remediation performance, DNAPL TCE dissolution and rhamnolipid-enhanced dissolution in heterogeneous porous media system exhibited multi-step mass-flux reduction/mass-removal behavior due to the presence of less hydraulically-accessible pool-dominated TCE source zone. However, mass removal and mass-flux reduction relationships for rhamnolipid flushing cases exhibited more ideal removal behavior, indicating the more efficient remediation performance compared to water flooding alone. For all cases, the later stage of mass removal was controlled by the more poorly-accessible mass associated with pool-dominated source zones. The results of this study revealed the impact of non-uniformity of the flow-field and effect of enhanced-solubilization agent on mass removal and mass-flux reduction behavior for DNAPL source zones in saturated porous media</p>

Flow Characterization in Triply Periodic Minimal Surface (TPMS)-Based Porous Geometries: Part 1—Hydrodynamics

The modeling of flow and heat transfer in porous media systems has always been a challenge, and the extended Darcy transport models are used for macro-level analysis. However, these models are subjected to the limitations depending upon the porous geometry such as pore size, pore type, effective porosity, tortuosity, permeability, and the flow characteristics. The forced convective flow of an incompressible viscous fluid through a channel filled with four different types of porous geometries constructed using the Triply Periodic Minimal Surface (or TPMS) model is presented in this study. Four TPMS lattice shapes, namely Diamond, I-WP, Primitive, and Gyroid, are created with same volume fraction of solid subdomain as 0.68 (or void fraction as 0.32). Using different configurations for the solid subdomain by treating it as (a) solid, (b) fluid, and (c) porous zone, three different classes of porous structures are further generated for each TPMS lattice. The present study is executed with the objective to investigate the effect of shape–morphology, tortuosity, microporosity, and effective porosity on permeability and inertial drag factor. A pore-scale direct numerical simulation approach is performed for the first two types of porous media by solving the Navier–Stokes equations. The specific microporosity is quantitatively induced in the solid subdomain where Darcy–Forchheimer equation is solved, whereas the Navier–Stokes equations are solved for the void subdomain in the third type of porous media. The results reveal that Darcy flow regime exists up to the mean velocity value of U < 0.0025 m/s (Re < 10) for all the cases discussed here, and it deviates at the higher mean velocity. The conductance to the flow shown by Darcy number has the maximum and minimum values for the Primitive Type 2 and I-WP Type 1 cases. The inertial drag coefficient is minimum in Diamond lattice and maximum in Primitive lattice at lower porosity (0.32), while Primitive lattice has minimum and I-WP lattice has maximum value of inertial drag coefficient for higher porosity (~ 1).

Numerical simulation of bubble rising in porous media using lattice Boltzmann method

Rising bubble systems in porous media exist in a variety of industrial processes. However, the flow characteristics of the issue are not well understood. In this work, the rising of bubble/bubbles through two types of porous structures, namely, in-line structured pore and staggered structured pore, are studied using a large density ratio lattice Boltzmann model. The effects of Eötvös number, pore shape, viscosity ratio, initial bubble number, and arrangement manner of the initial bubbles on the bubble deformation, bubble rising velocity, residual bubble mass, bubble perimeter, and the number of bubble breakups are investigated. It is found that as the Eötvös number increases, the bubbles are more easily broken during the process of passing through the porous media, the shapes of the sub-bubbles deviate from the original ones more and more, the bubble perimeter increases, and the difference between the bubble dynamics obtained by the in-line and staggered porous media decreases. Compared to the results of circular and rectangular pores, the bubble rising through the diamondoid pore has a more considerable deformation, which causes a slower rising speed. Furthermore, in the case that two bubbles are originally placed under the porous medium, the bubble deformation is greater and the bubble fracture times increase if the initial bubbles are aligned vertically. The findings of this work can contribute to the understanding of gas–liquid two-phase flow in porous media.

Effect of Pore Space Stagnant Zones on Interphase Mass Transfer in Porous Media, for Two-Phase Flow Conditions

Interphase mass transfer is an important solute transport process in two-phase flow in porous media. During two-phase flow, hydrodynamically stagnant and flowing zones are formed, with the stagnant ones being adjacent to the interfaces through which the interphase mass transfer happens. Due to the existence of these stagnant zones in the vicinity of the interface, the mass transfer coefficient decreases to a certain extent. There seems to be a phenomenological correlation between the mass transfer coefficient and the extent of the stagnant zone which, however, is not yet fully understood. In this study, the phase-field method-based continuous species transfer model is applied to simulate the interphase mass transfer of a dissolved species from the immobile, residual, non-aqueous phase liquid (NAPL) to the flowing aqueous phase. Both scenarios, this of a simple cavity and this of a porous medium, are investigated. The effects of flow rates on the mass transfer coefficient are significantly reduced when the stagnant zone and the diffusion length are larger. It is found that the stagnant zone saturation can be a proxy of the overall diffusion length of the terminal menisci in the porous medium system. The early-stage mass transfer coefficient continuously decreases due to the depletion of the solute in the small NAPL clusters that are in direct contact with the flowing water. The long-term mass transfer mainly happens on the interfaces associated with large NAPL clusters with larger diffusion lengths, and the mass transfer coefficient is mainly determined by the stagnant zone saturation.

Fractal Dimension Analysis of Pores in Coal Reservoir and Their Impact on Petrophysical Properties: A Case Study in the Province of Guizhou, SW China

Coal is a complex, porous medium with pore structures of various sizes. Therefore, it is difficult to accurately describe the characteristics of pore structure by using the traditional geometry method. The results from the present investigation suggest that the porous media system of the coal reservoir has obvious fractal characteristics at different scales. To study the complexity of the pores in the coal reservoir, 27 coal samples from Guizhou, SW China were studied. The fractal dimensions of coal pores were calculated, and the fractal dimension of a pore in a coal reservoir can be classified into two types: percolation and diffusion. The comprehensive fractal dimension can be obtained using the weighted summation method and the pore volume fraction of different fractal segments as the weight. The percolation fractal dimensions (Dp) of coal samples are between 2.88 and 3.12, the diffusion fractal dimensions (Dd) are between 3.57 and 3.84, and the comprehensive fractal dimensions (Dt) are between 3.05 and 3.63. The Dd values of all coal samples are all larger than the Dp values, which indicates that the random distribution and complexity of diffusion pores in coal are stronger than those of the percolation pores. The percolation fractal dimension decreases as the maturity degree increases, whereas the diffusion and comprehensive fractal dimensions increase. The diffusion pore volume fraction and total pore volume are all highly correlated with the comprehensive and diffusion fractal dimensions, respectively. The correlation between the comprehensive fractal dimension, diffusion pore volume fraction, and coal reservoir porosity is negative exponential, whereas the correlation between the total pore volume and coal reservoir porosity is positive linear. In comparison with the percolation and diffusion fractal dimensions, the comprehensive fractal dimension is better suited for characterizing the permeability of coal reservoirs. The fractal analysis of this paper is beneficial for understanding the relationship between the fractal characteristics of coal pores and properties.

Asymptotic behavior of solutions to coupled porous medium systems with boundary degeneracy

This article concerns the asymptotic behavior of solutions of one-dimensional porous medium systems with boundary degeneracy in bounded and unbounded intervals. It is shown that the degree of the boundary degeneracy and the exponent of the nonlinear diffusion determine asymptotic behaviors of solutions. For the problem in a bounded interval, if the degeneracy is not strong, the problem admits both nontrivial global and blowing-up solutions, while if the degeneracy is strong enough, any nontrivial solution to the problem must blow up in a finite time. For the problem in an unbounded interval, the Fujita type blowing-up theorems are established and the critical Fujita exponent is formulated by the degree of the boundary degeneracy and the exponent of nonlinear diffusion.

Overview of In-Situ Gelation Behavior of Gel Systems in Porous Media

Cross-linked polymer gel has been widely applied in profile control and water plugging due to its effective cost, wide suitability, excellent performance, and flexible gelation time. Previous research mainly focused on the bottle tests, reaction kinetics, and rheological properties of the gels, but the works of literature about the in situ gelations of gel placement in the porous media are relatively few. The study of the in-situ gelation behavior of gel systems is widely summarized in this paper, and the research tendency is proposed. The important practical questions, including the accurate lateral distance of gel placement, the variation of gel properties, and the injection pressure profile in the process of gel injection, should be resolved by laboratory and numerical research to enhance gel treatment success rate.

Performance of FeS synthesized within the porous media for in-situ immobilization of arsenic under varying water chemistry and groundwater conditions

The objectives of the study are (i) to assess arsenic immobilization efficiency by in-situ synthesized FeS within the porous media under varying solution chemistry and (ii) the performance evaluation of FeS-sand matrix in removing arsenic under natural groundwater conditions. To achieve the objectives, column experiments were performed where FeS was synthesized within the porous media in-situ. Then the As (III) or As (V) solution was injected within the column, and the effluents were collected to measure arsenic (As) and iron (Fe) concentrations. The groundwater samples were collected from seventeen locations in West Bengal, India, and were characterized. The As removal efficiency by FeS-sand matrix from the selected groundwater samples was studied in the batch and column system. The result showed that a significant amount of arsenite [As (III), 71.7–74.9%] was immobilized in the FeS synthesized porous media. The solution pH and the concentration of As (III) have an insignificant effect on immobilizing As (III) in the porous media system in the pH range of 6–8. Arsenate [As (V)] immobilization was not very promising under the reducing condition by in-situ synthesized FeS in the porous media. The As (V) removal was slightly better at pH 6 (26.9%) compared to pH 8 (11.7%). The occurrence of As in the groundwater (ranging from 0.78 μg/L to 376 μg/L) of the region was found to be associated with aluminum (Al) and Fe. The As removal by FeS-sand matrix showed better performance at pH 6 (40.7 ± 8.6%) compared to that of pH 8 (29.2 ± 15.6%) in the batch system. The immobilization of As increased significantly (83%) when the As-contaminated groundwater (376 μg/L) was injected into the porous media containing in-situ synthesized FeS. The concentration of Fe also reduced significantly (<160 μg/L) at the effluent after 2 PVs, indicating a limited risk of release of Fe. Overall, it could be stated that in-situ synthesized FeS in the porous media has the potential to immobilize As under a reducing environment within a range of pH under the groundwater conditions.

Effects of Porous Media on Foam Properties

AbstractFoam flooding is an important pathway for enhanced oil recovery. However, the evaluation of foam properties is usually carried out in free space, which can not accurately reflect the performance of foam in porous oil formation. In the present work, by investigating the foamability and stability of foam systems in sand‐pack models with average pore throat radius from 1.24 μm to 4.28 μm, the effects of porous media on foam properties are studied. Compared with foam systems in free space, foam systems in porous media have longer foam half‐life, longer drainage half‐life, and higher foam comprehensive index. The foam volume of foam systems in porous media could be higher or lower than that in free space, depending on the average pore throat radius of the porous media. Generally, in porous media, with the decreasing of pore throat radius, the foamability of the foam systems gradually decreases while the foam stability gradually increases. Moreover, the bubble size and liquid film thickness also decrease with the decreasing of pore throat radius of the porous media. Above all, the behaviors of foams are significantly affected by porous media. When investigating a foam system to evaluate its performance for foam flooding in oil recovery or other applications in porous media, porous models which could reflect the target conditions should be considered to obtain more trustable results.

Cooperative effect of surfactant and porous media on CO2 hydrate formation and capacity of gas storage

Hydrate-based technology is considered to be a promising approach widely applied in the areas of industrial natural gas storage and transportation, CO2 capture and storage. The major technical issues related to this technology are enhancing the formation rate and gas storage capacity under different conditions. In this work, the formation characteristics of CO2 hydrate were investigated in porous media below the freezing point in the presence of SDS (Sodium Dodecyl Sulfate). The influence of cooperative effect of surfactant and porous media on hydrate formation was investigated at different concentration of SDS. The results indicated that surfactant could obviously promote the formation process of CO2 hydrate in porous media when the concentration of SDS was in the range of 0–1240 ppm and the temperature ranged from 268.15 K to 272.15 K. However, there was an optimal SDS concentration to promote the formation process of CO2 hydrate in porous media below the freezing point. When the SDS concentration was 240 ppm, the highest conversion rate of ice to hydrate and the largest gas storage capacity were obtained, which were 43.05% and 80.06 L/L, respectively. The results also indicated that, with or without SDS in porous media system, the higher the temperature was, the less time it brought to reach 90% of the CO2 gas absorption (t90). But the maximum gas storage capacity of CO2 hydrate was obtained at 270.15 K in porous media in the presence of SDS. In addition, the results demonstrated that the SDS concentration of 0.24 g/L could increase the gas storage capacity of hydrate and shorten the value of t90 at different temperature conditions. These results are helpful for comprehensively understanding the rapid formation of CO2 hydrate in industrial areas and providing an important theoretical guidance and reference for the CO2 capture and storage in the form of hydrate.

Experimental investigation for the dynamic adsorption behaviors of gel system with long slim sandpack: Implications for enhancing oil recovery

The retention of gel system in porous media results in the reduction of porosity and permeability. However, the length of the current experiment models (sandpack or core sample) are in the range of centimeter scale, which is too short to track the full movement path of gel particles. In this work, a series of gel flooding experiments were conducted on 2.5-m long slim sandpack models. Seven fluid collection/pressure monitoring points were equally distributed along the length of the slim sandpack to track the movement of gel particles during the flooding process. We quantified the adsorption capacity, adsorption velocity, and mechanical shear effect of polymer/cross-linking agent along the flowing direction. In addition, we also employed scanning electron microscope (SEM) equipment to observe the morphology of the gel and the pore structure along the flooding direction, which provides good evidences of the adsorption retention and mechanical shear effects. Results show that most of the polymers and cross-linking agent were adsorbed on the region near the inlet. We emphasized the advantages of using long sandpack/core to track the full movement path of the gel system. In addition, the morphology of the original gel system showed a network characteristic of hexagonal structure, which was dragged to an elongated structure or even totally broke when it was transported through the porous medium. This work provides the fundamental understandings of the dynamic adsorption behaviors of gel system, which could be useful for optimizing the components of gel system, selection of target oil reservoirs and their operational parameters during gel flooding in enhancing oil recovery.

Scalable semismooth Newton methods with multilevel domain decomposition for subsurface flow and reactive transport in porous media

Large-scale modeling and predictive simulations of the subsurface flow and reactive transport system in porous media is significantly challenging, due to the high nonlinearity of the governing equations and the strong heterogeneity of material coefficients. The design of novel mathematical models and state-of-the-art methods for the flow simulation through porous media typically needs to satisfy the so-called bound-preserving property, i.e., the computed solution should stay inside a physically meaningful range. This paper presents a robust, scalable numerical framework based on the variational inequality formulation and the semismooth Newton method in a fully implicit manner, to model and simulate highly nonlinear flows without violating the boundedness requirement of the solution. Rigorous theoretical analysis for the variational inequality formulation of the problem is provided for facilitating the design of algorithms. Specifically, our approach further enhances the numerical formulation by utilizing a family of multilevel monolithic overlapping Schwarz methods for efficiently preconditioning, and the parallel implementation of the bound-preserving solver is based on the fast and robust domain decomposition technique. Numerical experiments are presented to demonstrate the efficiency and parallel scalability of the solution strategy for both standard benchmarks as well as realistic flow problems involving strong heterogeneity and high nonlinearity. We also show that the proposed framework is more robust and efficient than the commonly used inexact Newton algorithm in terms of the bound-preserving property.

Research on Percolation Characteristics of a JANUS Nanoflooding Crude Oil System in Porous Media.

According to the research status of low-permeability reservoir development, in order to find an intelligent and efficient displacement method, a Janus smart nanocapsule (embedding nanomaterials with surfactant function into the polymer) is developed in this paper. There are two kinds of phase fluids in the migration of porous media, the initial Janus intelligent microcapsule slow-release liquid (dissolved and undissolved AP-g-PNIPAAM and Janus functional particle ternary dispersion) and the later AP-g-PNIPAAM and Janus functional particle binary dispersion. Comprehensively, using the indoor oil displacement experiment, the seepage characteristics of the Janus smart nanocapsule (JSNC) in porous media are studied, and their macro and micro oil displacement mechanisms are revealed. Research shows that Janus intelligent microcapsules have good mobility control ability in low-permeability heterogeneous reservoirs. The displacement performance of stepped differential pressure shows that the displacement medium can expand the swept volume. The research results presented can show that the JSNC oil displacement system has great application potential for the development of low-permeability reservoirs.