Chemical Migration and Emulsification of Surfactant-Polymer Flooding

With a long sand-packed core with multiple sample points, a laboratory surfactant-polymer flooding experiment was performed to study the emulsification mechanism, chemical migration mechanism, and the chromatographic separation of surfactant-polymer flooding system. After water flooding, the surfactant-polymer flooding with an emulsified system enhances oil recovery by 17.88%. The water cut of produced fluid began to decrease at the injection of 0.4 pore volume (PV) surfactant-polymer slug and got the minimum at 1.2 PV. During the surfactant-polymer flooding process, the loss of polymer is smaller than that of surfactant, the dimensionless breakthrough time of polymer is 1.092 while that of surfactant is 1.308, and the dimensionless equal concentration distance of the chemical is 0.65. During surfactant-polymer flooding, the concentration of surfactant controls the formation of the emulsion. From 50 cm to 600 cm, as the migration distance increases, the concentration of surfactant decreases, and the emulsification strength and duration decrease gradually. With the formation of emulsion, the viscosity of the emulsion is relatively stable, which is beneficial to enhanced oil recovery. With the shear of reservoirs and migration of surfactant-polymer slug, the emulsion is formed to improve the swept volume and sweep efficiency and enhance oil recovery.

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An Easy Calculation Method on Sweep Efficiency of Chemical Flooding

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.275-277.496 ◽

2013 ◽

Vol 275-277 ◽

pp. 496-501

Author(s):

Fu Qing Yuan ◽

Zhen Quan Li

Keyword(s):

Oil Recovery ◽

Orthogonal Design ◽

Polymer Flooding ◽

Water Flooding ◽

Solution Viscosity ◽

Chemical Flooding ◽

Oil Viscosity ◽

Sweep Efficiency ◽

Easy Calculation ◽

Polymer Compound

According to the geological parameters of Shengli Oilfield, sweep efficiency of chemical flooding was analyzed according to injection volume, injection-production parameters of polymer flooding or surfactant-polymer compound flooding. The orthogonal design method was employed to select the important factors influencing on expanding sweep efficiency by chemical flooding. Numerical simulation method was utilized to analyze oil recovery and sweep efficiency of different flooding methods, such as water flooding, polymer flooding and surfactant-polymer compound flooding. Finally, two easy calculation models were established to calculate the expanding degree of sweep efficiency by polymer flooding or SP compound flooding than water flooding. The models were presented as the relationships between geological parameters, such as effective thickness, oil viscosity, porosity and permeability, and fluid parameters, such as polymer-solution viscosity and oil-water interfacial tension. The precision of the two models was high enough to predict sweep efficiency of polymer flooding or SP compound flooding.

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Laboratory Study on EOR in Offshore Oilfields by Variable Concentrations Polymer Flooding

The Open Petroleum Engineering Journal ◽

10.2174/1874834101710010094 ◽

2017 ◽

Vol 10 (1) ◽

pp. 94-107 ◽

Cited By ~ 1

Author(s):

Kaoping Song ◽

Ning Sun ◽

Yanfu Pi

Keyword(s):

Oil Recovery ◽

Field Application ◽

Polymer Flooding ◽

Water Flooding ◽

Displacement Efficiency ◽

Constant Concentration ◽

Sweep Efficiency ◽

Displacement Effect ◽

Fracture Pressure ◽

Recovery Technique

Background: Polymer flooding is the most commonly applied chemical enhanced-oil-recovery technique in offshore oilfields. However, there are challenges and risks in applying the technology of polymer flooding to offshore heavy oil development. Objective: This paper compared the spread law and the displacement effect of different injection modes and validated the feasibility of enhancing oil recovery by variable concentrations polymer flooding. Method: Two types of laboratory experiments were designed by using micro etching glass models and heterogeneous artificial cores. Furthermore, in order to determine a better polymer flooding mode, the displacement results, displacement characteristic curves and oil saturation distribution of heterogeneous artificial cores were also compared, respectively. Results: The experimental results showed that the recovery of variable concentrations polymer flooding was higher than that of constant concentration polymer flooding, under conditions of same total amount of polymer and similar water flooding recovery. Its sweep efficiency and displacement efficiency were also significantly higher than those of constant concentration polymer flooding. Moreover, variable concentrations polymer flooding had lower peak pressure and was at lower risk for reaching the formation fracture pressure. Conclusion: As a consequence, variable concentrations polymer flooding has certain feasibility for heterogeneous reservoir in offshore oilfields, and can improve interlayer heterogeneity to further tapping remaining oil in medium and low permeability layer. Conclusions of this paper can provide reference for the field application of polymer flooding in offshore oilfields.

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Experimental Study on the Physical Performance and Flow Behavior of Decorated Polyacrylamide for Enhanced Oil Recovery

Energies ◽

10.3390/en12030562 ◽

2019 ◽

Vol 12 (3) ◽

pp. 562 ◽

Cited By ~ 6

Author(s):

Shuang Liang ◽

Yikun Liu ◽

Shaoquan Hu ◽

Anqi Shen ◽

Qiannan Yu ◽

...

Keyword(s):

Interfacial Tension ◽

Enhanced Oil Recovery ◽

Oil Recovery ◽

Flow Behavior ◽

Polymer Flooding ◽

Water Flooding ◽

Displacement Effect ◽

Microscale Model ◽

Water Cut ◽

Viscosity Stability

With the rapid growth of energy consumption, enhanced oil recovery (EOR) methods are continually emerging, the most effective and widely used was polymer flooding. However, the shortcomings were gradually exposed. A novel decorated polyacrylamide might be a better alternative than polymer. In this work, the molecular structure and the properties reflecting the viscosity of decorated polyacrylamide, interfacial tension, and emulsification were examined. In order to better understand the interactions between decorated polyacrylamide and oil as well as the displacement mechanism, the displacement experiment were conducted in the etched-glass microscale model. Moreover, the coreflooding comparison experiments between decorated polyacrylamide and polymer were performed to investigate the displacement effect. The statistical analysis showed that the decorated polyacrylamide has excellent characteristics of salt tolerance, viscosity stability, and viscosification like polymer. Besides, the ability to reduce the interfacial tension in order 10−1 and emulsification, which were more similar to surfactant. Therefore, the decorated polyacrylamide was a multifunctional polymer. The displacement process captured by camera illustrated that the decorated polyacrylamide flooded oil mainly by means of ‘pull and drag’, ‘entrainment’, and ‘bridging’, based on the mechanism of viscosifying, emulsifying, and viscoelasticity. The results of the coreflooding experiment indicated that the recovery of decorated polyacrylamide can be improved by approximately 11–16% after water flooding when the concentration was more than 800 mg/L, which was higher than that of conventional polymer flooding. It should be mentioned that a new injection mode of ‘concentration reduction multi-slug’ was first proposed, and it obtained an exciting result of increasing oil production and decreasing water-cut, the effect of conformance control was more significant.

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Analytical Model of Waterflood Sweep Efficiency in Vertical Heterogeneous Reservoirs under Constant Pressure

Mathematical Problems in Engineering ◽

10.1155/2016/6273492 ◽

2016 ◽

Vol 2016 ◽

pp. 1-9 ◽

Cited By ~ 3

Author(s):

Lisha Zhao ◽

Li Li ◽

Zhongbao Wu ◽

Chenshuo Zhang

Keyword(s):

Analytical Model ◽

Oil Recovery ◽

Constant Pressure ◽

Water Saturation ◽

Water Injection ◽

Single Layer ◽

Sweep Efficiency ◽

Heterogeneous Reservoirs ◽

Water Cut ◽

Swept Volume

An analytical model has been developed for quantitative evaluation of vertical sweep efficiency based on heterogeneous multilayer reservoirs. By applying the Buckley-Leverett displacement mechanism, a theoretical relationship is deduced to describe dynamic changes of the front of water injection, water saturation of producing well, and swept volume during waterflooding under the condition of constant pressure, which substitutes for the condition of constant rate in the traditional way. Then, this method of calculating sweep efficiency is applied from single layer to multilayers, which can be used to accurately calculate the sweep efficiency of heterogeneous reservoirs and evaluate the degree of waterflooding in multilayer reservoirs. In the case study, the water frontal position, water cut, volumetric sweep efficiency, and oil recovery are compared between commingled injection and zonal injection by applying the derived equations. The results are verified by numerical simulators, respectively. It is shown that zonal injection works better than commingled injection in respect of sweep efficiency and oil recovery and has a longer period of water free production.

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Experimental Study of Microgel Conformance-Control Treatment for a Polymer-Flooding Reservoir Containing Superpermeable Channels

SPE Journal ◽

10.2118/205486-pa ◽

2021 ◽

pp. 1-13

Author(s):

Yang Zhao ◽

Jianqiao Leng ◽

Baihua Lin ◽

Mingzhen Wei ◽

Baojun Bai

Keyword(s):

Polymer Solution ◽

Oil Recovery ◽

Polymer Flooding ◽

Control Treatment ◽

Void Space ◽

Sweep Efficiency ◽

Microgel Particles ◽

Water Cut ◽

Preformed Particle Gels ◽

Bypassed Oil

SummaryPolymer flooding has been widely used to improve oil recovery. However, its effectiveness would be diminished when channels (e.g., fractures, fracture-like channels, void-space conduits) are present in a reservoir. In this study, we designed a series of particular sandwich-like channel models and tested the effectiveness and applicable conditions of micrometer-sized preformed particle gels (PPGs, or microgels) in improving the polymer-flooding efficiency. We studied the selective penetration and placement of the microgel particles, and their abilities for fluid diversion and oil-recovery improvement. The results suggest that polymer flooding alone would be inefficient to achieve a satisfactory oil recovery as the heterogeneity of the reservoir becomes more serious (e.g., permeability contrast kc/km > 50). The polymer solution would vainly flow through the channels and leave the majority of oil in the matrices behind. Additional conformance-treatment efforts are required. We tried to inject microgels in an attempt to shut off the channels. After the microgel treatment, impressive improvement of the polymer-flooding performance was observed in some of our experiments. The water cut could be reduced significantly by as high as nearly 40%, and the sweep efficiency and overall oil recovery of the polymer flood were improved. The conditions under which the microgel-treatment strategy was effective were further explored. We observed that the microgels form an external impermeable cake at the very beginning of microgel injection and prevent the gel particles from entering the matrices. Instead, the microgel particles could selectively penetrate and shut off the superpermeable channels under proper conditions. Our results suggest that the 260-µm microgel particles tested in this study are effective to attack the excessive-water-production problem and improve the oil recovery when the channel has a high permeability (>50 darcies). The gels are unlikely to be effective for channels that are less than 30 darcies because of the penetration/transport difficulties. After the gels effectively penetrate and shut off the superpermeable channel, the subsequent polymer solution is diverted to the matrices (i.e., the unswept oil zones) to displace the bypassed oil. Overall, this study provides important insights to help achieve successful polymer-flooding applications in reservoirs with superpermeable channels.

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Technologies for Reusing Resources in Abandoned Oilfield after Tertiary Oil Recovery

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.368-370.249 ◽

2013 ◽

Vol 368-370 ◽

pp. 249-256

Author(s):

Xian Jie Shao ◽

Yuan Yuan Kang ◽

Cai Feng Wang ◽

Er Shuang Gao ◽

Xin Hui Che ◽

...

Keyword(s):

Production Rate ◽

Oil Recovery ◽

Polymer Flooding ◽

Water Flooding ◽

Chemical Flooding ◽

Displacement Efficiency ◽

Steam Flooding ◽

Lab Experiments ◽

High Production Rate ◽

Water Cut

In traditional views, oilfield is abandoned after water flooding and chemical flooding. But the recovery is only 50%~60%，that is to say, more than 40% of the resource is still left underground. Therefore, how to utilize this part of resource economically and effectively is a key problem to be tackled. Based on the lab experiments and theoretical researches on viscosity-temperature relationship, displacement and relative permeability under high temperature, the mechanism of enhancing oil recovery through steam flooding in super-high water cut stage of water injection oilfield was analyzed. The experimental results showed that steam flooding in 200°C after polymer flooding could increase oil displacement efficiency by 14.5%. Water flooding and polymer flooding had been implemented in Sabei development area of Daqing Oilfield since it was brought into development in 1963. The recovery had reached above 70% and the water cut had exceeded 98%. There was no economic benefit to develop continually, the oilfield faced abandonment. Steam flooding test was carried out to enhance oil recovery on this basis. According to the geological characteristics and development status, special technical measures were taken based on the lab experiments and numerical simulation including high-pressure steam injection to improve heat utilization, forced fluid withdrawal to increase production rate, insulated tubing and nitrogen insulation to keep the bottom hole steam dry, and tracking analysis to adjust injection-production parameters duly. The ultimate recovery reached 81.6％ which increased 10.7% on the original basis, the field test was successful technically. Steam flooding is characterized with quick effect, high production rate and high producing degree of residual oil. This successful technology provides a direction for secondary development after polymer flooding in water flooding oilfield.

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A Pore-Scale Investigation of Residual Oil Distributions and Enhanced Oil Recovery Methods

Energies ◽

10.3390/en12193732 ◽

2019 ◽

Vol 12 (19) ◽

pp. 3732 ◽

Cited By ~ 7

Author(s):

Yaohao Guo ◽

Lei Zhang ◽

Guangpu Zhu ◽

Jun Yao ◽

Hai Sun ◽

...

Keyword(s):

Porous Media ◽

Enhanced Oil Recovery ◽

Oil Recovery ◽

Polymer Flooding ◽

Water Flooding ◽

Scale Model ◽

Pore Scale ◽

Residual Oil ◽

Sweep Efficiency ◽

Significant Difference

Water flooding is an economic method commonly used in secondary recovery, but a large quantity of crude oil is still trapped in reservoirs after water flooding. A deep understanding of the distribution of residual oil is essential for the subsequent development of water flooding. In this study, a pore-scale model is developed to study the formation process and distribution characteristics of residual oil. The Navier–Stokes equation coupled with a phase field method is employed to describe the flooding process and track the interface of fluids. The results show a significant difference in residual oil distribution at different wetting conditions. The difference is also reflected in the oil recovery and water cut curves. Much more oil is displaced in water-wet porous media than oil-wet porous media after water breakthrough. Furthermore, enhanced oil recovery (EOR) mechanisms of both surfactant and polymer flooding are studied, and the effect of operation times for different EOR methods are analyzed. The surfactant flooding not only improves oil displacement efficiency, but also increases microscale sweep efficiency by reducing the entry pressure of micropores. Polymer weakens the effect of capillary force by increasing the viscous force, which leads to an improvement in sweep efficiency. The injection time of the surfactant has an important impact on the field development due to the formation of predominant pathway, but the EOR effect of polymer flooding does not have a similar correlation with the operation times. Results from this study can provide theoretical guidance for the appropriate design of EOR methods such as the application of surfactant and polymer flooding.

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Evaluation of Polymer Flooding in a Highly Stratified Heterogeneous Reservoir. A Field Case Study

WSEAS TRANSACTIONS ON ENVIRONMENT AND DEVELOPMENT ◽

10.37394/232015.2020.16.3 ◽

2020 ◽

Vol 16 ◽

Keyword(s):

Oil Recovery ◽

History Matching ◽

Lower Layer ◽

Polymer Flooding ◽

Economic Life ◽

Water Flooding ◽

Base Case ◽

Sweep Efficiency ◽

Sector Model ◽

Reservoir Simulator

Oil and gas companies are looking for proven hydrocarbon reserves from their mature drained reservoirs to extend the production and economic life of these fields. The chemical enhanced oil recovery (CEOR) is an attractive water-based EOR method for these mature fields. The polymer flooding (PF) is a widely applied process in reservoirs with low sweep efficiency after the water flooding (WF). The target Colombian field has one of the first polymer pilots in the region with positive results of oil recovery in “A” sands. Thus, the operator is interested in the expansion of PF for the same reservoir and even in deeper reservoir sands. This paper focuses in the evaluation of different scenarios of PF for the producer in layers A and B with a mechanistic simulation model, thus obtaining new recommendations for the recovery strategy in the field. A sector model was constructed from a full field model using a commercial reservoir simulator to the in-house chemical flooding reservoir simulator: UTCHEMRS. This sector model was also migrated to a second commercial simulator allowing a performance comparison for these three simulators. UTCHEMRS model results were compared with the commercial simulators through the history matching (HM) phase. The primary and waterflood history match was in agreement with the field data. Simulation results suggested that PF for the base case in “A” sands presented an incremental oil recovery of up to 12% additional to water flooding. Additionally, PF was extended to the lower layer “B” sand to investigate the potential of polymer injection. The PF injection in both reservoirs simultaneously loses sweep efficiency and decreases the oil recovery to about 3%. However, a hypothetical case of new infill producer wells with the objective of testing the individual reservoir performance has revealed that PF is having significant upside from B sands as well.

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Experimental Study on Medium Viscosity Oil Displacement Using Viscoelastic Polymer

Geofluids ◽

10.1155/2018/4321380 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 3

Author(s):

Huiying Zhong ◽

Qiuyuan Zang ◽

Hongjun Yin ◽

Huifen Xia

Keyword(s):

Oil Recovery ◽

Polymer Flooding ◽

Water Soluble ◽

Water Flooding ◽

Bohai Bay ◽

Residual Oil ◽

Displacement Efficiency ◽

Sweep Efficiency ◽

Oil Displacement ◽

Medium Viscosity

With the growing demand for oil energy and a decrease in the recoverable reserves of conventional oil, the development of viscous oil, bitumen, and shale oil is playing an important role in the oil industry. Bohai Bay in China is an offshore oilfield that was developed through polymer flooding process. This study investigated the pore-scale displacement of medium viscosity oil by hydrophobically associating water-soluble polymers and purely viscous glycerin solutions. The role and contribution of elasticity on medium oil recovery were revealed and determined. Comparing the residual oil distribution after polymer flooding with that after glycerin flooding at a dead end, the results showed that the residual oil interface exhibited an asymmetrical “U” shape owing to the elasticity behavior of the polymer. This phenomenon revealed the key of elasticity enhancing oil recovery. Comparing the results of polymer flooding with that of glycerin flooding at different water flooding sweep efficiency levels, it was shown that the ratio of elastic contribution on the oil displacement efficiency increased as the water flooding sweep efficiency decreased. Additionally, the experiments on polymers, glycerin solutions, and brines displacement medium viscosity oil based on a constant pressure gradient at the core scale were carried out. The results indicated that the elasticity of the polymer can further reduce the saturation of medium viscosity oil with the same number of capillaries. In this study, the elasticity effect on the medium viscosity oil interface and the elasticity contribution on the medium viscosity oil were specified and clarified. The results of this study are promising with regard to the design and optimum polymers applied in an oilfield and to an improvement in the recovery of medium viscosity oil.

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Adaptive study on polymer flooding of secondary reservoir and infilling uniform

MATEC Web of Conferences ◽

10.1051/matecconf/201817501006 ◽

2018 ◽

Vol 175 ◽

pp. 01006

Author(s):

Xu WenBo

Keyword(s):

Oil Recovery ◽

Physical Simulation ◽

Injection Pressure ◽

Leading Edge ◽

Polymer Flooding ◽

Water Flooding ◽

Monitoring Methods ◽

Sweep Efficiency ◽

Plane Sweep ◽

Polymer Injection

For the main polymer flooding oilfield expansion and infill wells three times the area of deployment, the proposed development mode II oil reservoir of polymer flooding and thin and poor combination of three encryption. In this paper, the use of leading edge water monitoring methods and principles of the plane heterogeneity through physical simulation to study the effects of different mining methods II oil and a combination of the three encryption effects of flooding. Studies have shown that, together with the water flooding recovery can be increased by nearly 19 percent, higher than the water poly alternate drive about 4%, the injection pressure is about three types of reservoir 0.3MPa, flat stage water flood sweep efficiency compared with an average of 30.95%. Meanwhile polymer injection can increase oil recovery by 21%, but the limited ability of three types of oil injection, polymer injection pressure during injection 0.22PV up to 0.8MPa, water flooding stage by an average of 30 percent compared to the plane sweep efficiency. The water flooding recovery poly alternately raise only 15%, an average increase of 26.95 percent driven phase plane sweep efficiency than water. Theoretical results of this study may provide a reliable basis for the future development of efficient thin and poor reservoirs.

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