Swept Volume Research Articles

The experimental investigation of performance behaviors of a beta-type Stirling engine with bell-crank motion mechanism

The current study aims to develop a novel power generation system that is capable of working with a Stirling engine. Within this context, a β-type Stirling engine design has been created with a bell-crank motion mechanism and a 365 cm3 swept volume. The engine has been manufactured, and then a detailed assessment has been conducted to determine the impact of the motion mechanism on engine performance characteristics. The designed and manufactured engine has been tested using a range of working fluids, such as air, argon, carbon dioxide, helium, and nitrogen gases. The performance tests of this engine have been carried out at 1000 K (±10) heater and 300 K (±5) coolant temperatures. Based on the outcomes of the experimental studies, the highest engine power and torque values have been obtained at a charge pressure of 4 bar using helium gas, with 143.5 W at 267 rpm and 7.75 Nm at 100 rpm, respectively. Moreover, the maximum engine power values obtained from other tests with nitrogen, air, carbon dioxide and argon gases have been compared with helium gas. Helium gas has been found to outperform nitrogen, air, carbon dioxide, and argon gases in tests by 67.3%, 73.9%, 197.1%, and 200.2%, respectively. Finally, the highest thermal efficiency value has been obtained with helium gas as 48.7% at a charge pressure of 4 bar.

Study on Microscopic Oil Displacement Mechanism of Alkaline-Surfactant-Polymer Ternary Flooding.

Alkali-surfactant-polymer (ASP) flooding is one of the most effective and promising ways to enhance oil recovery (EOR). The synergistic effect between alkali, surfactant, and polymer can respectively promote emulsification performance, reduce interfacial tension, and improve bulk phase viscosity, thus effectively improving flooding efficiency. However, the displacement mechanism of ASP flooding and the contribution of different components to the oil displacement effect still need further discussion. In this study, five groups of chemical slugs were injected into the fracture model after water flooding to characterize the displacement effect of weak alkali, surfactant, polymer, and their binary/ternary combinations on residual oil. Additionally, the dominant mechanism of the ASP flooding system to improve the recovery was studied. The results showed that EOR can be improved through interfacial reaction, low oil/water interfacial tension (IFT), and increased viscosity. In particular, the synergistic effect of ASP includes sweep and oil washing. As for sweep, the swept volume is expanded by the interfacial reaction between the alkali and the acidic components in Daqing crude oil, and the polymer increases the viscosity of the system. As for oil washing, the surfactant generated by the alkali cooperates with surfactants to reduce the IFT to an ultra-low level, which promotes the formation and migration of oil-in-water emulsions and increases the efficiency of oil washing. Overall, ASP can not only activate discontinuous oil ganglia in the pores within the water flooding range, but also emulsify, decompose, and migrate the continuous residual oil in the expanded range outside the water flooding. The EOR of ASP is 38.0% higher than that of water flooding. Therefore, the ASP system is a new ternary composite flooding technology with low cost, technical feasibility, and broad application prospects.

Fast and accurate modelling of twin-screw compressors: A generalised low-order approach

Twin-screw compressors (TSC) are commonly used in heat pump processes due to their robustness and flexibility. They exhibit two core properties, i.e. the swept volume and the built-in volume ratio (BVR), which heavily influence their capacity limits and off-design efficiency. This work presents a new low-order model (i.e. a polynomial model), which can accurately predict a TSC’s behaviour. The model uses the external pressure ratio and volumetric compressor inlet flow rate to calculate isentropic efficiency and compressor speed. The input parameters are normalised with a reference flow rate (calculated from the swept volume) and the BVR, respectively. This results in a generalised model of low numerical cost, which can be used for explorative studies independent of the specific machine size and BVR. A gain in computational speed by a factor of 375 is achieved compared to a semi-empiric reference model. The model displays very good predictive accuracy when used to predict the performance of machines with similar BVRs, but different sizes. A mean deviation from the manufacturer data of 4.29%, 0.88°C and 1.38% for the shaft power, the outlet temperature and the compressor speed can be observed, respectively. When there is a difference in size and BVR, the prediction accuracy is still reasonable but significantly declines for small and very large pressure ratios. Nevertheless, the proposed new approach extends the state-of-the-art by introducing a low-order model, which combines the advantages of low computational cost, high accuracy, physically correct predictions over a wide operational range and scalability to different machine capacities and BVRs. The validation for different fluids indicates a good general prediction accuracy relatively independent of the used fluid.

Reliable and Accurate Implicit Neural Representation of Multiple Swept Volumes with Application to Safe Human–Robot Interaction

In automated production using collaborative robots in a manufacturing cell, a crucial aspect is to avoid collisions to ensure the safety of workers and robots in human–robot interaction. One approach for detecting collisions is using the swept volume (SV) to identify safe protective space for operation. We learn an accurate and reliable signed distance function (SDF) network from raw point clouds of a pre-computed SV to represent a class of linear joint motion trajectories. The network requires only a set of parameters and constant execution time, thus reducing the computational time and memory of collision checking due to the complexity of explicit geometry during task execution. The distance of collision danger foresaw by the learned SDF is exploited to reduce the frequency of collision detection calls in the dynamic environment and reduce the computational cost further. We assess the relative merits of the implicit neural representation of multiple SVs in terms of F1-score, error distance from the surface of the truth geometry, and 3D visualization by comparing favorably with a binary voxel network for learning a single SV with similar inference time. All the predicted errors of the geometry lie within a distance of 4 voxels from the surface of the truth geometry, and most reconstruction errors are within 3 voxels. A simulation of pick-and-place task execution in the human–robot interaction scenarios by leveraging the learned SDF as an efficient continuous collision detector is performed. The improvement in execution time and collision detection number is validated in the simulation.

Development and performance evaluation of nonionic surfactant-stabilized nanoemulsion for enhanced oil recovery applications in tight reservoir

Nanoemulsions have garnered great attention as a chemical additive for enhanced oil recovery (EOR) technology worldwide due to their small size and unique physicochemical properties. Herein, this work introduces a novel nonionic surfactant-stabilized nanoemulsion prepared using a low-energy method for EOR projects in the Chang 8 tight reservoir. Spontaneous imbibition experiments were conducted in oil-saturated cores, and secondary imbibition experiments were carried out in water-bearing cores. Additionally, core flooding experiments were performed to study the EOR performance of both nanoemulsion and complex surfactant. Finally, the EOR mechanisms were thoroughly investigated, specifically focusing on oil-washing capacity, reduced interfacial tension, and wettability alteration. The designed nanoemulsion, with droplets averaging 10.5 ± 0.7 nm in synthetic formation brine at ambient temperature, exhibits excellent thermal and long-term stability even under reservoir temperature conditions. The oil recovery efficiency of the nanoemulsion system in oil-saturated cores through spontaneous imbibition was 31.28%, representing a 6.42% improvement over the complex surfactant solution. In the secondary imbibition experiments, the nanoemulsion mobilized 8.53% of the residual oil, compared to 4.11% for the complex surfactant. Core flooding experiments revealed that the nanoemulsion system achieved a total oil recovery of 62.69%, outperforming the complex surfactant system by 8.68% during the chemical flooding stage and 1.82% during the subsequent brine flooding stage. The EOR mechanisms of nanoemulsion in tight reservoirs can be attributed to four aspects: reduction of oil/water interfacial tension, wettability alteration, miscibility with crude oil, and increased sweep volume. The generation of the Marangoni effect and the adsorption and diffusion characteristics are essential differences between the nanoemulsion system and the complex surfactant system. The presented findings in this paper could aid in promoting the large-scale use of nanoemulsions in Chang 8 tight reservoirs.

A strong stability gel foam for water shutoff during oil and gas reservoir development

In view of the short effective period of conventional foam for water shutoff during oil and gas reservoir development, a strong stability gel foam system is proposed in this work. By comparing the foam properties of different foaming systems, the optimized formulation of foam system is “0.3% SDS (sodium dodecyl sulfate) + 0.4% HPAM (partially hydrolyzed polyacrylamide) + 0.3% SD-107 (organic chromium).” At 50 °C and 10 000 mg/l salinities, the volume of foam is basically unchanged after a short time of defoaming and finally remains above 70%, and the drainage half-life can reach 16 days. The polymer and crosslinker form a stable three-dimensional network structure on the Plateau boundary after foaming, which has good viscosity and viscoelasticity. The foam system has excellent temperature and salt resistance. It is appropriate for medium and low temperature shallow reservoirs. The foam system has a good plugging efficiency. It can effectively plug the fracture and improve the sweep volume, which has a good application prospect.

Investigation on the flow behavior and mechanisms of water flooding and CO2 immiscible / miscible flooding in shale oil reservoirs

Shale reservoirs represent a significant untapped source of recoverable oil, and even a slight increase in recovery can yield substantial benefits. In recent years, there has been a growing interest in the development of shale reservoirs due to their vast potential. Shale reservoirs are characterized by their intricate pore structures, ultra-low porosity, and extremely low permeability. Consequently, fluid flow within shale formations is highly complex, and the distribution of shale oil is diverse. There is an urgent need to conduct research into the flow behavior of shale reservoirs and the modes of crude oil occurrence within them, in order to support effective shale oil extraction in the field. In this work, we established a MCMP-MRT-LBM model considering nano-scale confinement effects such as slip and adsorption. The model is employed to simulate single pore channels and blind-end pores to investigate the distinct mechanisms involved in water flooding, CO2 immiscible flooding, and CO2 miscible flooding. Subsequently, the research explores the fluid flow characteristics associated with these three development methods within porous media, as well as the distribution of remaining oil. Then we compared the oil displacement efficiency, swept volume, actual liquid injection volume and displacement front position of the three fluids in porous media. The results reveal that water flooding exhibits superior displacement performance in single pore channels, while CO2 miscible flooding proves to be the most effective method for exploiting oil in blind-end pores. In porous media, CO2 miscible flooding successfully mitigates fingering phenomena and efficiently recovers crude oil located at blind-end and corner regions of the pores. The recovery efficiency achieved through CO2 miscible flooding is approximately 30% higher than that of water flooding and about 10% greater than CO2 immiscible flooding.

Deep Depth from Focal Stack with Defocus Model for Camera-Setting Invariance

We propose deep depth from focal stack (DDFS), which takes a focal stack as input of a neural network for estimating scene depth. Defocus blur is a useful cue for depth estimation. However, the size of the blur depends on not only scene depth but also camera settings such as focus distance, focal length, and f-number. Current learning-based methods without any defocus models cannot estimate a correct depth map if camera settings are different at training and test times. Our method takes a plane sweep volume as input for the constraint between scene depth, defocus images, and camera settings, and this intermediate representation enables depth estimation with different camera settings at training and test times. This camera-setting invariance can enhance the applicability of DDFS. The experimental results also indicate that our method is robust against a synthetic-to-real domain gap.

Eco-friendly calcium alginate microspheres enable enhanced profile control and oil displacement

Polymer microspheres (PMs), such as polyacrylamide, have been widely applied for enhanced oil recovery (EOR), yet with environmental concerns. Here, we report a microfluid displacement technology containing a bio-based eco-friendly material, i.e., calcium alginate (CaAlg) microspheres for EOR. Two dominant mechanisms responsible for EOR over CaAlg fluid have been verified, including the microscopic oil displacement efficacy augmented by regulating capillary force (determined by the joint action of interfacial tension and wettability between different phases) and macroscopic sweep volume increment through profile control and mobility ratio reduction. This comprehensive effectiveness can be further impacted when the CaAlg microsphere is embellished ulteriorly by using appropriate amount of sodium dodecyl sulfonate (SDS). The core flooding and nuclear magnetic resonance (NMR) tests demonstrate that CaAlg-SDS microsphere can balance the interphase property regulation (wettability alteration and IFT reduction) and rheology properties, enabling simultaneous profile control and oil displacement. Excessive introduction of SDS will have a negative impact on rheological properties, which is not favored for EOR. Our results show that the involvement of 4-mM SDS will provide the best behavior, with an EOR rate of 34.38%. This cost-effective and environmentally-friendly bio-microsphere-based microfluidic displacement technology is expected to achieve “green” oil recovery in future oilfield exploitation.

Influence of reservoir heterogeneity on immiscible water-alternating-CO2 flooding: A case study

Currently, limited studies of immiscible water-alternating-CO2 (imWACO2) flooding focus on the impact of reservoir heterogeneity on reservoir development outcomes. Given this, using the heterogeneous reservoirs in the Gao 89-1 block as a case study, this study conducted slab core flooding experiments and numerical simulations to assess the impact of reservoir heterogeneity on imWACO2 flooding efficiency. It can be concluded that imWACO2 flooding can enhance the sweep volume and oil recovery compared to continuous CO2 flooding. As the permeability difference increases, the difference in the swept volume between zones/layers with relatively high and low permeability increases. To optimize the exploitation of reservoirs in the Gao 89-1 block, the optimal timing and CO2 injection rate for imWACO2 flooding are determined at water cut of 40% and 10000 m³/d, respectively. A short injection-production semi-period, combined with multiple cycles of water and CO2 injection alternations, is beneficial for enhanced oil recovery from imWACO2 flooding.

A modified vertical-horizontal well pattern for enhancing in-situ combustion performance in extra-heavy oil reservoirs

A proper well pattern is critical for the efficient and economical exploitation of heavy oil and bitumen during the in-situ combustion (ISC). This paper brings a modified vertical-horizontal well pattern named the modified THAI process using additional injectors in staggered line drive with auxiliary gas producer wells and investigates its ISC performance using a 3D experimental simulation. The burning stability, spatial distribution of coke zone, pressure difference, and extension features of combustion chamber are studied and analyzed. Results show that a better burning state and stable propagation for the combustion front can be achieved in this modified well pattern. Spatial distribution of coke zone structure manifests a larger sweep volume of combustion chamber and a lower extent of combustion override. Combustion chamber extension characteristics are intuitively displayed by the variation of 350 °C isothermal surfaces, and its sweep volume finally enlarges to 53032.55 cm3 with a volumetric sweep coefficient of 47.95%. The production well intermittent shutdown (PWIS) method can improve unfavorable expansion behaviors of combustion chamber with little impact on the burning state and pressure difference. The oil displacement efficiency eventually reaches 85.6%. This well pattern exhibits significant potential for enhancing in-situ combustion performance, contributing to the economic and efficient exploitation of oil in commercial ISC application.

Quantitative evaluation of water-alternative-natural gas flooding in enhancing oil recovery of fractured tight cores by NMR

As the associated gas of tight reservoirs, natural gas is abundant and noncorrosive, which is more suitable for the development of tight oil reservoirs in China. However, the mechanism of gas injection development is unclear, and the gas channeling is serious in tight reservoirs after fracturing. The water-alternating-gas (WAG) flooding is an effective means to delay gas channeling and improve oil recovery. Therefore, it is significant to clarify the mechanism of preventing gas channeling and recovering oil by water-alternation-natural gas (WANG) flooding. The WANG flooding experiments with different water–gas slugs were conducted in non-fracture and fractured tight cores. Besides, the oil distribution of different pore spaces of cores before and after displacement and the main contribution spaces on oil recovery were quantitatively analyzed by using nuclear magnetic resonance and core mercury porosimetry techniques. The results indicate that compared with natural gas flooding, the WANG flooding can retard gas channeling, increase formation energy, and enhance oil recovery by up to 14.1%, especially in fractured cores. Under the resistance of water slugs, the gas was allowed to enter smaller pores and its swept volume was expanded. Oil is mainly stored in mesopores (0.1–1 μm) and small pores (0.01–0.1 μm), accounting for over 90% of the total volume. The oil recovered mainly comes from mesopores, which accounts for over 75% of the total amount. Moreover, the WANG flooding strengthens the recovery of oil in mesopores and macropores (1–10 μm), but it also squeezes oil into small pores and micropores (0.001–0.01 μm).

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.

Wide-baseline view synthesis for light-field display based on plane-depth-fused sweep volume

The advancements in three-dimensional (3D) display technology have led to a wide interest in light-field display. However, the need to simultaneously capture a large number of object views made content generation for light-field displays still a bottleneck. In this paper, we propose a method for light-field content generation based on plane-depth-fused sweep volume (PDFSV), focusing on handling wide-baseline views and exhibiting scene generalization when the camera array remains unchanged. Specifically, the proposed PDFSV exploits the prior depth of the images captured by a 4 × 4 spherical camera array to represent 3D information of scenes. Then two optimized sequential convolutional neural networks (CNN) are employed for implicit depth modeling and final color calculation, respectively. By doing these, the prior depth facilitates the synthesis of regions with complex textures in the target view. We produce a Wide-baseline Multi-view Image Set (WMIS) which has a field of view (FOV) angle reaching 54°and could be publicly available for access. In our experiments, we use only the 4 vertex views as input. Results demonstrate that the proposed approach can synthesize high-quality views at arbitrary positions between sparse views, outperforming existing neural-radiance-fields-based (NeRF-based) methods. Finally, we conduct autostereoscopic display experiments, achieving satisfactory results.

An amphiphilic nano calcium carbonate: Preparation, emulsification, interface properties, and displacement mechanism in low permeability reservoir

More extensive attention has been directed toward amphiphilic nanomaterials in the field of chemical enhanced oil recovery owing to they have the same excellent properties as surfactants. In this work, an amphiphilic nano calcium carbonate(ANCC) was prepared by chemical one-pot synthesis of NCC and alkyl acid. ANCC had a lipophilic property, which can make the oil and water were completely emulsified at the concentration of 500 ppm to form W/O emulsion with a particle size of 0.2–2.6 µm. ANCC had best dispersion effect at the solution of 0.1% Tween80. In the oil-water phase, ANCC can be adsorbed on the oil-water interface to reduce interface tension, and increase interface strength, and improve emulsion stability. The lipophilic slide can be changed from lipophilic to hydrophilic when immersed in the nanofluid. Using TW-ANCC (0.1% of Tween80 +500 ppm of ANCC) as the oil displacement fluid, which improved oil recovery by 23.3% in the single core displacement experiment and by 36.9% in the flat panel visualization experiment with comparing primary water flooding. The oil displacement mechanism of TW-ANCC was obtained by the etched glass micromodel experiment and the nuclear magnetic resonance experiment, the result shown that TW-ANCC can enhance oil recovery by reducing interface tension, changing rock wettability, reducing flow in high permeability zone, and expanding sweep volume in low permeability zones.

Enhanced recovery of tight reservoirs after fracturing by natural gas huff-n-puff: Underlying mechanisms and influential factors

Tight oil resources are abundant in the world. It is very important to strengthen the research on the development theory and technology of tight oil reservoirs for ensuring national energy security. Natural gas huff-n-puff can effectively improve the oil recovery of tight oil reservoirs. However, the pore-scale oil production characteristics and the mechanisms of natural gas huff-n-puff in matrix-fracture cores are poorly understood. The influence degree of important factors on oil recovery is not clear and the interactions between factors are rarely considered. In this paper, the oil production characteristics and mechanisms of natural gas huff-n-puff in tight cores with different fracture lengths were quantitatively analyzed by combining nuclear magnetic resonance (NMR) with numerical simulation technology. The influencing factors and their interactions were evaluated by the response surface method (RSM). The results show that tight cores mainly consist of medium pores (0.1–1 μm) and small pores (0.01–0.1 μm). The fracture mainly increases the proportion of macro-pores (1–10 μm) and medium pores. In the natural gas huff-n-puff process, crude oil from macro-pores (1–10 μm) and medium pores is mainly developed, and the contribution percentage of crude oil in medium pores to oil recovery is the largest, up to 98.28%. The position of gas–oil contact (GOC) moves deeper as the number of huff-n-puff cycles increases. The contents of CH4 and CO2 in the oil phase remain at a high level within the GOC, while between the GOC and the component sweep front, the contents of CH4 and CO2 in the oil phase decrease with the increase in dimensionless distance. The gas component sweep volume is increasing with the increase in fracture length. Moreover, the injected natural gas mainly extracts C3–C10 components from crude oil. The reduction law of crude oil viscosity is consistent with the migration laws of CH4 components along the path. Compared with soaking time and gas diffusion coefficient, the injection pressure is the most significant factor underlying the recovery of natural gas huff-n-puff in tight cores. Besides the influence of single-factor, the interaction effects of gas injection pressure and diffusion also should be considered to determine the huff-n-puff parameters in the field implementation of natural gas huff-n-puff in tight reservoirs after fracturing.

Online motion planning based on swept volume search with replanning using sequential quadratic programming

This paper describes a method for obtaining a mobile manipulator's motion sequence by indicating a goal-hand pose. The proposed method entails recording various robot motions as a large number of motion sequences and associated swept volumes (SVs) and then selecting the most appropriate SV for the current situation. In addition, the motion sequences can be altered while the robot is in motion, and the transition motion is generated using sequential quadratic programming, enabling the robot to avoid collisions with obstacles found after it has begun to move. The proposed method's performance is verified by simulation to confirm the appropriate amount of data and the method's superiority.

Development of an in situ emulsifying/ultra-low-interfacial-tension cyclic flooding system for medium- and low-permeability reservoirs

Medium- and low-permeability reservoirs are important in oilfield development. However, due to their characteristics of poor pore permeability and high heterogeneity, the development of suitable technologies has been very difficult. In this study, an in situ emulsifying/ultra-low-interfacial-tension cyclic flooding system has been developed for low- and medium-permeability reservoirs. Based on the hydrophilic-lipophilic balance (HLB) value method, an emulsifying surfactant ASD with Span 80 (sorbitan monooleate) as the main component has been identified as highly promising through screening. At mass fractions of surfactant ASD between 0.2% and 0.6%, the extent of water separation from the emulsion is greatly reduced, and the W/O emulsion can effectively improve the mobility ratio and increase the sweep volume. The surfactant SA synthesized in our laboratory reduces the interfacial tension of crude oil to 10−4 mN m−1. Laboratory core flooding experiments have shown that multiple rounds of alternating injection with aqueous solutions of surfactants ASD and SA can improve oil recovery by 22.25%. Upon injecting a low-viscosity aqueous solution of surfactant ASD, it emulsifies crude oil in situ under reservoir conditions, solving the problems of difficult polymer injection and insufficient spread. Our work provides useful insights for the development of low- and medium-permeability reservoirs.

Influence of Internal Structural Parameters on the Inner Flow and Outer Spray Characteristics for Feedback-Free Fluidic Oscillator

Feedback-free fluidic oscillators, relying on the interaction of jets to oscillate, have a wide range of operation frequencies and no moving parts, which is promising for future applications. In this paper, the sweep angle, oscillation frequency, and volume flow rate of the feedback-free fluidic oscillator with a cavity width of 4.6 mm were measured experimentally, and the sweeping mechanism was analyzed based on the internal flow simulation. The influence of the impact angle, cavity exit width, and shoulder radius on the internal flow and external spray characteristics was analyzed by the numerical method. The results show that the sweep angle and oscillation frequency are affected throughout the increase in impact angle from 80° to 120°. However, only when the SR is greater than 0.88 mm does the internal flow and spray state change significantly. The volume flow rate is mainly affected by the cavity exit width and increases linearly from 5.3 mL/s to 9.3 mL/s as the width increases from 0.45 mm to 0.85 mm. It can be surmised that the sweep angle is approximately linear with the distance between the hit point and the impact cavity centerline.

Experimental Study on the Enhanced Oil Recovery Mechanism of an Ordinary Heavy Oil Field by Polymer Flooding.

It is widely known that in the water flooding development process of ordinary heavy oil, the fingering phenomenon is obvious, there are a lot of unswept areas, and absolutely, the recovery is really very low. In addition, for some shallow and thin ordinary heavy oil reservoirs limited by the geological conditions of the reservoir, the thermal recovery technology also has serious heat loss and high development cost. Therefore, there is an urgent need to transform the development and further improve the enhanced oil recovery (EOR). In this paper, the mechanism of EOR by polymer flooding was investigated for high-porosity and high-permeability terrestrial ordinary heavy oil reservoirs. Through laboratory experiments, we analyzed the characteristics of oil-water relative permeability curves, mobility control ability, and microscopic seepage characteristics during polymer flooding of ordinary heavy oil reservoirs. On this basis, the effect of the mobility ratio on seepage characteristics and the mechanism of EOR enhancement were clarified. The results show that the polymer can effectively improve the mobility control effect of the displacing fluid. As the polymer solution and ordinary heavy oil have the characteristics of high viscosity and low mobility, there is a minimum mobility ratio in the process of polymer flooding. Namely, the characteristics of dual low mobility exist in the process of polymer flooding for the ordinary heavy oil. It effectively enhances the profile control and plugging ability of the polymer, thus expanding the sweep volume of larger pores and improving the displacement efficiency of smaller pores. Based on the two factors mentioned above, it is found that the dual low mobility characteristics can improve the recovery of ordinary heavy oil by polymer flooding. Therefore, it is proposed that an enhanced profile control and plugging effect due to the dual low mobility characteristics is an important EOR mechanism for ordinary heavy oil development by polymer flooding.