Viscosity Ratio Research Articles

Flow Rate Dependency of Steady-State Two-Phase Flows in Pore Networks: Universal, Relative Permeability Scaling Function and System-Characteristic Invariants

The phenomenology of steady-state two-phase flow in porous media is conventionally recorded by the relative permeability diagrams in terms of saturation. Yet, theoretical, numerical and laboratory studies of flow in artificial pore network models and natural porous media have revealed a significant dependency on the flow rates—especially when the flow regime is capillary to capillary/viscous and part of the disconnected non-wetting phase remains mobile. These studies suggest that relative permeability models should incorporate the functional dependence on flow intensities. In the present work, a systematic dependence of the pressure gradient and the relative permeabilities on flow rate intensity is revealed. It is based on extensive simulations of steady-state, fully developed, two-phase flows within a typical 3D model pore network, implementing the DeProF mechanistic–stochastic model algorithm. Simulations were performed across flow conditions spanning 5 orders of magnitude, both in the capillary number, Ca, and the flow rate ratio, r, and for different favorable /unfavorable viscosity ratio fluid systems. The systematic, flow rate dependency of the relative permeabilities can be described analytically by a universal scaling function along the entire domain of the independent variables of the process, Ca and r. This universal scaling comprises a kernel function of the capillary number, Ca, that describes the asymmetric effects of capillarity across the entire flow regime—from capillarity-dominated to mixed capillarity/viscosity- to viscosity-dominated flows. It is shown that the kernel function, as well as the locus of the cross-over relative permeability values, are single-variable functions of the capillary number; they are both identified as viscosity ratio invariants of the system. Both invariants can be correlated with the structure of the pore network, through a function of Ca. Consequently, the correlation is associated with the wettability characteristics of the system. Among the potential applications, the proposed, universal, flow rate dependency scaling laws are the improvement of core analysis and dynamic rock-typing protocols, as well as integration into field-scale simulators or associated machine learning interventions for improved specificity/accuracy.

Influence of pipeline diameters and fluid properties on slug frequency in horizontal pipelines

The accurate prediction of slug frequency is critical for the construction of multiphase flow models and the flow assurance of oil and gas pipelines. In this paper, the slug frequency data are obtained by visualization method in short (65 mm ID, 215 D) and long (46 mm ID, 35957 D) pipelines. The slug frequency of horizontal pipeline is inversely proportional to pipeline diameter (26–300 mm) and proportional to the liquid viscosity (1.01–7500 mPa·s). The quasi-developed distance for the air–water slug flow at VSG ≤ 1.00 m/s is about 1200 D, and the frequency of the quasi-developed slug flow is less affected by the pipeline length. Based on the gas Strouhal number and the liquid viscosity ratio, the quantitative relation between the slug frequency data at different viscosities is constructed, and a new correlation is developed to predict both the slug frequency of water and viscous liquids.

Controlling the properties of metakaolin-based geopolymer/liquid organic waste emulsions: A rheological approach

Addressing a critical challenge in the nuclear industry, this study contributes to the effective and sustainable management of radioactive liquid organic waste by studying the effect of the viscosity ratio between the geopolymer grouts and the incorporated organic liquids (OL) on the efficiency of the solidification process. This research provides a practical pathway for industries to manage their liquid organic wastes more effectively, economically, and in alignment with regulatory standards. Three mineral oils are used to simulate OL wastes with an incorporation rate fixed at 30% vol. which represents a considerable proportion from an industrial point of view. To ensure adequate conditioning, the focus of this work is on the effect of the viscosity difference between geopolymer grouts and incorporated OL on the rheological, mechanical, and microstructural properties of geopolymer/OL composites. In total, 9 viscosity ratios, ranging from 0.4 to 430, are tested by varying the viscosity of both the geopolymer grouts and the incorporated OL. First, the results obtained show that OLs with a viscosity higher than 0.05 Pa.s can be efficiently encapsulated in MK-based geopolymer grouts, without requiring any surfactants. This study also confirms that the viscosity ratio is a key factor controlling the formulation and the rheological characteristics of fresh geopolymer/OL emulsions. Accordingly, increasing the geopolymer grout viscosity is an efficient technique for the preparation of geopolymer/OL composites with finely encapsulated OL droplets. In addition, based on the experimental results obtained in this study, a good correlation is established between the rheological parameters of the emulsions and the viscosity of the two phases (geopolymer and OL). This enables the proposition of empirical models that allow estimating the final rheological parameters of the fresh emulsions with an accuracy exceeding 90%. Finally, in terms of mechanical properties, this study confirms that MK-based geopolymers can safely be used for the solidification of a high amount of OL wastes.

Dynamics of a droplet in shear flow by smoothed particle hydrodynamics

The behavior of a droplet under shear flow in a confined channel is studied numerically using a multi-phase smoothed particle hydrodynamics (SPH) method. With an extensive range of Reynolds number, capillary number, wall confinement, and density/viscosity ratio between the droplet and the matrix fluid, we are able to investigate systematically the droplet dynamics such as deformation and breakup. We conduct the majority of the simulations in two dimensions due to economical computations, while perform a few representative simulations in three dimensions to corroborate the former. Comparison between current results and those in literature indicates that the SPH method adopted has an excellent accuracy and is capable of simulating scenarios with large density or/and viscosity ratios. We generate slices of phase diagram in five dimensions, scopes of which are unprecedented. Based on the phase diagram, critical capillary numbers can be identified on the boundary of different states. As a realistic application, we perform simulations with actual parameters of water droplet in air flow to predict the critical conditions of breakup, which is crucial in the context of atomization.

Influence of rheology on mixing homogeneity and mechanical behavior of twin-pipe 3D printable concrete

The twin-pipe pumping technology has been developed for the stiffening control of 3D printable concrete, which is achieved by pumping two different mixtures separately and blending these mixtures using a static mixer before extrusion. The combination of the two mixtures undergoes a significant phase transition in the static mixer from liquid to solid due to accelerated hydration. The phase transition, as well as the mechanical performance of hardened elements, is strongly influenced by the mixing homogeneity of the mixtures. In this study, we examine how the rheological behavior of the two mixtures being combined in the static mixer affects the mixing homogeneity. The rheological behavior was studied by performing flow curve measurements using a dynamic shear rheometer. To characterize the mixing homogeneity, polished cross-sections of 3D-printed elements were prepared and characterized using an innovative macropixel-based image analysis procedure. Specifically, the image analysis-based procedure involves identifying the two mixtures by applying color segmentation, followed by the Poole index method to assess the mixing homogeneity. The results indicate that a low yield stress, especially for the main constituent mixture of which the flow rate is higher than the second constituent mixture, is advantageous to achieve a higher mixing homogeneity. The viscosity or the viscosity ratio of the two constituent mixtures is found to have a minor influence on the mixing homogeneity.

Experimentally investigating the pressure drop of liquid-liquid Taylor flows over varying viscosity ratios

Micro-capillary liquid-liquid Taylor flows have emerged as a promising new platform for achieving higher heat and mass transfer compared to single-phase flows. In any application benefiting from such flows, pressure drop is a fundamental characteristic in evaluating the required input power in order to achieve an optimum configuration. Despite several attempts to develop an all-encompassing model to estimate pressure drop in immiscible liquid-liquid flows, existing models are still limited to narrow ranges of Reynolds, Capillary and Weber numbers and are insufficiently accurate over a wide range of viscosity ratios. To push the limits, the present study proposes a new expression for interfacial pressure drop based on experimental investigations over a wide range of Capillary (3×10−4≤CaC≤7.6×10−2), Reynolds (0.1≤ReC≤49) and Weber (7×10−4≤We≤1.5) numbers while continuous to dispersed viscosity ratio (μC/μD) spanned from 0.058 to23.2. To obtain these ranges, five distinct liquid-liquid fluid combinations were examined within a capillary of diameter 800 µm. A novel experimental setup is employed in this study to ensure high accuracy and repeatability of the measurements. The strengths and weaknesses of existing models are identified and a more fundamental understanding of predicting pressure drop in Taylor flow regimes is developed. The new model uses standard Hagen–Poiseuille flow theory in combination with an empirical optimized term for predicting the effect of differential Laplace pressure between leading/trailing caps of dispersed phase droplets. This correlation fits the experimental data within ±20% and can provide a prediction certainty for estimating pressure drop in applications that deal with such flows.

Dual transition scheme on [formula omitted]-equation model

The proposed model integrates two transition mechanisms into the turbulent kinetic energy (k-equation) turbulence framework, assisted by transition representatives. These include a “flow-structure-adaptive” stress-intensity parameter, which induces the pre-transitional/pseudo-laminar state before transition, and an intermittency factor, which facilitates the prediction of flow transition onset and completion with a feasible growth rate and a logical transition length. The algebraic transition model introduces new functions and correlations, which are based on theoretical and experimental evidence. These elements stimulate multiple transition phenomena in a suitable and credible way due to their reliance on local flow information for initiating and controlling the transition growth rate. With the employment of an algebraic closure for the dissipation rate, the k-equation directly anticipates the free-stream turbulence intensity instead of the free-stream “eddy-to-laminar” viscosity ratio (Rμ∞). This approach avoids the “trial-and-error” inconsistency typically associated with most correlation-based and physics-based transition models when initiating appropriate computations. The independence of the algebraic transition model from Rμ∞ offers substantial benefits in predictive capability over traditional transition models. However, the quality of performance might fluctuate, contingent on the closure approximations adopted. This detail is of immense importance for accurately depicting the pertinent physical characteristics of the flow, such as bypass, natural, and separation-induced transitions. Numerical results indicate that the current model, whether equipped with algebraic transition additives or not, aligns well with both existing experimental data and commonly used transition and non-transition models. The new transition model has decent agreement with the transitional boundary layer on a flat plate, and transitional flow over an airfoil with laminar and turbulent separation bubbles.

Rheology of a dilute binary mixture of inertial suspension under simple shear flow

Abstract The rheology of a dilute binary mixture of inertial suspension under simple shear flow is analyzed in the context of the Boltzmann kinetic equation. The effect of the surrounding viscous gas on the solid particles is accounted for by means of a deterministic viscous drag force plus a stochastic Langevin-like term defined in terms of the environmental temperature Tenv. Grad’s moment method is employed to determine the temperature ratio and the pressure tensor in terms of the coefficients of restitution, concentration, the masses and diameters of the components of the mixture, and the environmental temperature. Analytical results are compared against event-driven Langevin simulations for mixtures of hard spheres with the same mass density m1/m2 = (σ(1)/σ(2))3, mi and σ(1) being the mass and diameter, respectively, of the species i. It is confirmed that the theoretical predictions agree with simulations of various size ratios σ(1)/σ(2) and for elastic and inelastic collisions in a wide range of parameter space. It is remarkable that the temperature ratio T1/T2 and the viscosity ratio η1/η2 (ηi being the partial contribution of the species i to the total shear viscosity η = η1 + η2) discontinuously change at a certain shear rate as the size ratio increases; this feature (which is expected to occur in the thermodynamic limit) cannot be completely captured by simulations due to the small system size. In addition, a Bhatnagar–Gross–Krook (BGK)-type kinetic model adapted to mixtures of inelastic hard spheres is exactly solved when Tenv is much smaller than the kinetic temperature T. A comparison between the velocity distribution functions obtained from Grad’s method, the BGK model, and simulations is carried out.

Improving the performance of a diesel engine using nanomaterials and chlorella vulgaris microalgae blends assisted with biogas

Microalgae-based fuel has attracted attention as a green energy source for the transportation sector owing to its high suitability, availability, and rapid growth rate. Furthermore, algae consume carbon dioxide to produce fuel, and indirectly reduce global warming. This study predicts the effects of microalgae biofuel blends assisted by biogas and nanoparticles on diesel engine performance, combustion, and emission characteristics across various engine speeds for the first time. Biogas, which is rich in carbon monoxide and hydrogen, passed through the intake manifold at a constant flow rate of 10 L per minute. Al2O3 nanoparticles were dispersed in the biodiesel at a concentration of 100 ppm. The inclusion of hydrogen enhanced both the brake power and brake thermal efficiency of the engine irrespective of engine speed. A blend of both biogas and nanoparticles resulted in less specific fuel consumption than Chlorella vulgaris biodiesel blends owing to lower viscosity and higher energy ratio. However, the inclusion of nanoparticles reduced the in-cylinder pressure. In terms of emissions, all the microalgae blends exhibited reduced formation of carbon monoxide, carbon dioxide, and hydrocarbon compared to diesel. However, the formation of nitrogen of oxides in 20% microalgae blend A20 was higher than that in diesel and 20% microalgae blend with nanoparticle (AB20 N). Owing to the presence of CO in the biogas, the total accumulation of CO and CO2 was higher for AB20 N than for other fuel blends. From the above analysis, it is clear that CO can be used in conjunction with hydrogen to assist the internal combustion process.

Turbulent statistics and interface dynamics in a lubricated channel flow at Re_{tau }=100

In this work we aim to study, through the use of Direct Numerical Simulations (DNS), the turbulent drag reduction (DR) that occurs in a lubricated channel during the transport of a fluid at a low Reynolds number. In this situation, one of the two fluids separates the second from the wall forming a thin layer in contact with it. In our configuration the thin lubricating layer is adjacent to one of the wall, which will be called lubricated side and and we consider the same density (rho _1=rho _2) for the two fluids, while for the viscosity ratio (lambda = nu _1/nu _2) we will consider two different values: lambda = 1 and lambda = 0.5. Moreover to assess the role of the surface tension we have duplicated the two simulations at We number of We=0.055 and We=0.5. As expected the DR mechanism is strongly related to the viscosity ratio, in particular the flow rate increase when decreasing lambda due to a relaminarization of the lubricated layer. Moreover, the parametric analysis on the effect of viscosity ratio and surface tension allows us to highlight very interesting modulations of the dynamics of the interface and of the turbulent kinetic budgets. To date, the latest studies in this area have been carried out using the Phase Field Method for the description of the interface. One of the scopes of the present study is to confirm and extend the existing results by exploring the dynamics of the flow with the use of the volume of fluid method.

Dynamics of Microbubbles Oscillating in Rheopectic Fluids Subject to Acoustic Pressure Field

In the present work, the dynamics of a single spherical gas bubble surrounded by a rheopectic fluid obeying the Quemada model is numerically investigated while the bubble undergoes oscillatory motion due to acoustic forcing. The generalized form of the Rayleigh–Plesset equation has been used for studying bubble dynamics in Quemada fluids. The integro-differential equation representing the dynamics of the bubble is solved numerically using the finite-element method (FEM) and also the Gauss–Laguerre quadrature (GLQ) method. The effect of rheopexy number (Rx) and viscosity ratio (ξ) are then investigated over a wide range of working parameters. Numerical results show that the rheopectic behavior of the fluid surrounding the bubble can dramatically affect the bubble dynamics. It is predicted that for highly anti-thixotropic fluids, harmonics are affected so much so that the bubble may exhibit chaotic behavior. For instance, at Rx = 0.001 and ξ = 1/81, a one-micron-sized bubble may attain a size almost 30 times of its initial size. The general conclusion is that, in sonography, microbubbles dispersed in rheopectic fluids may indeed be considered as a potent ultrasound contrast agent provided that the fluid is just moderately anti-thixotropic otherwise its chaotic response might damage the adjacent tissues.

Mechanism of synergistic stabilization of emulsions by amorphous taro starch and protein and emulsion stability.

Amorphous taro starch (TS)/whey protein isolate (WPI) mixtures were prepared using pasting treatment. The TS/WPI mixtures and their stabilized emulsions were characterized to determine the emulsion stability and the mechanism of synergistic stabilization of emulsions. As WPI content increased from 0% to 13%, the paste final viscosity and retrogradation ratio of the TS/WPI mixture gradually decreased from 3683 cP to 2532 cP and from 80.65% to 30.51%, respectively. As the WPI content increased from 0% to 10%, the emulsion droplet size decreased gradually from 96.81μm to 10.32μm, and the storage modulus G' and stabilities of freeze-thaw, centrifugal, and storage increased gradually. Confocal laser scanning microscopy revealed that WPI and TS were mainly distributed at the oil-water interface and droplet interstice, respectively. Thermal treatment, pH, and ionic strength had little influence on the appearance but had different influences on the droplet size and G', and the rates of droplet size and G' increase under storage varied with different environmental factors.

Numerical investigation of viscous fingering in a three-dimensional cubical domain

We perform three-dimensional numerical simulations to understand the role of viscous fingering in sweeping a high-viscous fluid (HVF). These fingers form due to the injection of a low-viscous fluid (LVF) into a porous media containing the high-viscous fluid. We find that the sweeping of HVF depends on different parameters such as the injection velocity (U0) of the LVF, ease of diffusion of the fluid (D), and the logarithmic viscosity ratio of HVF and LVF ℜ. The two-phase Darcy's law module of COMSOL Multiphysics is used to simulate different cases with varying parameters. At high values of U0 and ℜ and lower values of D, the fingers grow non-linearly, resulting in earlier tip splitting of the fingers and breakthrough, further leading to poor sweeping of the HVF. In contrast, the fingers evolve uniformly at low values of U0 and ℜ, resulting in an efficient sweeping of the HVF, while a higher diffusion coefficient leads to a smooth flow with fewer fingers. We also estimate the sweep efficiency and conclude that the parameters U0, D, and ℜ be chosen optimally to minimize the non-linear growth of the fingers to achieve an efficient sweeping of the HVF.

Transition from viscous fingers to foam during drainage in heterogeneous porous media

We investigate the behavior of drainage displacements in heterogeneous porous media finding a transition from viscous fingering to foam-like region. A pore network model incorporating the formation of blobs is adopted to study this phenomenon. By imposing a pressure difference between the inlet and outlet, we observe that the displacement pattern undergoes a significant transition from a continuous front of growing viscous fingers to the emergence of foam, which develops and propagates until breakthrough. This transition occurs at a specific distance from the inlet, which we measure and analyze as a function of the viscosity ratio and the capillary number, demonstrating that it follows a non-trivial power-law decay with both the parameters. Moreover, we discuss the relationship between the evolution of the total flow rate and the local pressure drop, showing that the foam developed reduces global mobility. We observe that foam is formed from the fragmentation of viscous fingers beneath the front, and this instability mechanism is connected with fluctuations of the local flow rate, which we analyze both in the viscous fingering region and in the foam region.

Immiscible thermoplastic polymer blends with alternative layered encapsulation structure: Modeling and processing

“Encapsulation” is a common phenomenon during polymer melting processing, which supplied great opportunities for fabricating high-performance polymer products. In this work, two immiscible polymers, high density polyethylene (HDPE) and polyketone (PK), were used for preparing polymer blends with viscous encapsulation structures. Moreover, the effects of interfacial tension, viscosity ratio, and shear rate on the phase morphology evolution of HDPE/PK blends were investigated by numerical simulation and high-pressure capillary extrusion (HCE). Meanwhile, the formation mechanisms of HDPE/PK alternating layered encapsulation structure were explored by tracking the trajectory of PK droplets via numerical simulation. The results show that an alternative layered encapsulation structure of HDPE/PK was formed under the shear rate from 50 to 1000 s−1 with the interfacial tension over 1.35 mN/m. Moreover, it was found that the revealed mechanism in HCE was also applicable to the injection molding process. Therefore, this unique “microstructure-intelligent prediction-control” strategy of polymer blends is suitable for the industrial processing of high-performance polymer blends for desired applications.

Impact of Oil Viscosity on Dispersion in the Aqueous Phase of an Immiscible Two‐Phase Flow in Porous Media: An X‐Ray Tomography Study

AbstractIn this study, dispersion and mixing were studied in a steady two‐phase flow generated using a co‐injection method. The impact of oil viscosity was investigated over a large range of fluid viscosity ratios. The results indicate that highly heterogeneous flow fields are generated by a wide distribution of oil clusters with varied volumes. Variation in the velocity distribution enhanced the deformation and spreading of a tracer plume, resulting in large dispersion scales and accelerated spreading rates. The dispersion coefficients vary with time and exhibit a non‐Fickian dispersion during co‐injection. Consequently, anomalous mixing behaviors can be observed when the viscosity ratio exceeds 10. The mixing strength, characterized by the scalar dissipation rate, is first enhanced by distortion on the surface of the solute. Therefore, diffusion contributes to mixing, resulting in a faster decrease in the mixing strength in the late time regime. These results can be attributed to the fact that the non‐wetting fluid becomes disconnected, and the size of each cluster decreases as the oil viscosity increases. The formation of an oil film narrows pore spaces, and a lubrication effect of the oil film may contribute to the enhanced dispersion and mixing state, even with the low relative permeability of the wetting phase. This study provides insights into dispersion in partially saturated porous media with varied oil viscosities at both the macro and pore scales, which can further improve CO2 storage capacity and safety.

Analytical study of unsteady two-layer combined electroosmotic and pressure-driven flow through a cylindrical microchannel with slip-dependent zeta potential

For investigating dynamics of two-fluid co-flows at an arbitrary time, the unsteady two-layer pressure-driven electroosmotic flow in a cylindrical microchannel is studied. To propose a model of universal significance, the interfacial slip and slip-dependent zeta potential are incorporated. The momentum equations are analytically solved and the physical picture how the unsteady two-layer flow evolves into the steady state is provided by evaluating the transient velocities. The two-layer velocities or flow rates are computed at different slip coefficients, electrokinetic widths, viscosity ratios, density ratios, radius ratios and zeta potential ratios, thereby the resulting interactive influences are assessed. When considering slip-dependent zeta potential, the change in two-layer velocity with other parameters is more pronounced. The increasing rate of flow rate with slip coefficient augments with electrokinetic width and outer zeta potential, which decreases with radius ratio. This work establishes mechanisms for the enhancement of transporting efficiency in microdevices associated with multi-layer flows.

On the interaction of Taylor length-scale size droplets and homogeneous shear turbulence

The main objective of the present work is to explain the physical mechanisms occurring in droplet-laden homogeneous shear turbulence (HST) with a focus on the modulation of turbulence kinetic energy (TKE) caused by the droplets. To achieve such an objective, first, we performed direct numerical simulations (DNS) of HST laden with droplets of initial diameter approximately equal to twice the Taylor length scale of turbulence, droplet-to-fluid density and viscosity ratios equal to ten and a 5 % droplet volume fraction. We investigated the effects of shear number and Weber number on the modulation of TKE for $Sh \approx 2$ and $4$ , and $0.02 \le {{We_{rms}}} \le 0.5$ . Then, we derived the TKE equations for the two-fluid, carrier-fluid and droplet-fluid flow in HST and the relationship between the power of surface tension and the rate of change of total droplet surface area, providing the pathways of TKE for two-fluid incompressible HST. Our DNS results show that, for ${{We_{rms}}} = 0.02$ , the rate of change of TKE is increased with respect to the single-phase cases, for ${{We_{rms}}} = 0.1$ , the rate of change of TKE oscillates near the value for the single-phase cases and, for ${{We_{rms}}} = 0.5$ , the rate of change of TKE is decreased with respect to the single-phase cases. Such modulation is explained from the analysis of production, dissipation and power of surface tension in the carrier-fluid and droplet-fluid flows. Finally, we explain the effects of droplets on the production and dissipation rate of TKE through the droplet ‘catching-up’ mechanism, and on the power of the surface tension through the droplet ‘shearing’ mechanism.

Role of viscosity in turbulent drop break-up

We investigate drop break-up morphology, occurrence, time and size distribution, through large ensembles of high-fidelity direct-numerical simulations of drops in homogeneous isotropic turbulence, spanning a wide range of parameters in terms of the Weber number $We$ , viscosity ratio between the drop and the carrier flow $\mu _r=\mu _d/\mu _l$ , where d is the drop diameter, and Reynolds ( $Re$ ) number. For $\mu _r \leq 20$ , we find a nearly constant critical $We$ , while it increases with $\mu _r$ (and $Re$ ) when $\mu _r > 20$ , and the transition can be described in terms of a drop Reynolds number. The break-up time is delayed when $\mu _r$ increases and is a function of distance to criticality. The first break-up child-size distributions for $\mu _r \leq 20$ transition from M to U shape when the distance to criticality is increased. At high $\mu _r$ , the shape of the distribution is modified. The first break-up child-size distribution gives only limited information on the fragmentation dynamics, as the subsequent break-up sequence is controlled by the drop geometry and viscosity. At high $We$ , a $d^{-3/2}$ size distribution is observed for $\mu _r \leq 20$ , which can be explained by capillary-driven processes, while for $\mu _r > 20$ , almost all drops formed by the fragmentation process are at the smallest scale, controlled by the diameter of the very extended filament, which exhibits a snake-like shape prior to break-up.

Investigation of Polymer-Assisted CO2 Flooding to Enhance Oil Recovery in Low-Permeability Reservoirs.

CO2 flooding is a favorable technical means for the efficient development of low-permeability reservoirs, and it can also contribute to the realization of net-zero CO2 emissions. However, due to the unfavorable viscosity ratio and gravity overriding effect, CO2 channeling will inevitably occur, seriously affecting its storage and displacement effects. This paper conducts a systematic study on the application of polymer-assisted CO2 flooding in low-permeability reservoirs. Firstly, the polymer agent suitable for low-permeability reservoirs is optimized through the viscosity-increasing, rheological, and temperature- and salt-resistant properties of the solution. Then, the injectivity performance, resistance-increasing ability, and profile-improving effect of the polymer solution were evaluated through core experiments, and the optimum concentration was optimized. Finally, the enhanced oil recovery (EOR) effects of polymer-assisted and water-assisted CO2 flooding were compared. The results show that the temperature-resistant polymer surfactant (TRPS) has a certain viscosity-increasing performance, good temperature resistance performance, and can react with CO2 to increase the solution viscosity significantly. Meanwhile, TRPS has good injection performance and resistance-increasing effect. The resistance increasing factor (η and η') of TRPS-assisted CO2 flooding increases with increased permeability, the concentration of TRPS solution, and injection rounds. Considering η' and the profile improvement effect comprehensively, the application concentration of TRPS should be 1000 mg/L. The EOR effect of TRPS-assisted CO2 flooding is 8.21% higher than that of water-assisted CO2 flooding. The main effective period is in the first and second rounds, and the best injection round is three. The research content of this paper can provide data support for the field application of polymer-assisted CO2 flooding in low-permeability reservoirs.