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Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Physical Chemistry".

Deadline for manuscript submissions: closed (15 September 2024) | Viewed by 14254

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Dr. Lu Zhang

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Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China
Interests: surfactants; enhanced oil recovery; interfacial tension; interfacial rheology; wettability; emulsion; foam
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Dear Colleagues,

Surfactants can adsorb at the oil–water interface and greatly reduce oil–water interfacial tension, and thus, are widely used for improving oil recovery. In recent years, with the development of high-temperature and high-salinity reservoirs, heavy oil reservoirs, low-permeability reservoirs and other harsh-condition reservoirs, new functional requirements, such as temperature resistance, salt resistance, viscosity reduction, wetting modification and controllable emulsification performance, have been established for surfactants. The interfacial properties of new surfactants, such as extended and zwitterionic surfactants, have become a hot topic in recent years. As such, we are pleased to launch this Special Issue entitled "Surfactants at liquid interfaces: Applications in Enhanced Oil Recovery" to improve the current understanding of the structure–performance relationships of surfactants in the areas of enhanced oil recovery and interface science.

This Special Issue aims to collect original research and review articles on all aspects of the interface behavior of surfactants, especially extended and zwitterionic surfactants, for enhanced oil recovery.

Dr. Lu Zhang
Guest Editor

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Keywords

liquid interface
surfactant
adsorption
crude oil
enhanced oil recovery
interfacial tension

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Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery, 2nd Edition in Molecules

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20 pages, 5506 KiB

Open AccessArticle

Synthesis, Surface Activity, Emulsifiability and Bactericidal Performance of Zwitterionic Tetrameric Surfactants

by Xin Wei, Jie Li, Xiangfei Geng, Di Niu, Zhenjie Wei, Chenxu Wang, Ziqi Sun and Yangchun Xie

Molecules 2024, 29(18), 4286; https://doi.org/10.3390/molecules29184286 - 10 Sep 2024

Viewed by 912

Abstract

In this paper, a series of tetrameric surfactants (4C_nSAZs, n = 12, 14, 16) endowed with zwitterionic characteristic were synthesized by a simple and convenient method and their structures were characterized by FT-IR, ¹H NMR and elemental analysis. Their physicochemical properties were studied using the Wilhelmy plate method, fluorescence spectra and dynamic light scattering technique. 4C_nSAZs have higher surface activities and tend to adsorb at the air/water surface rather than self-assembling in aqueous solution. The thermodynamic parameters obtained from surface tension measurements show that both processes of adsorption and micellization of 4C_nSAZs are spontaneous and that the micellization processes of 4C_nSAZs are entropy-driven processes. Both adsorption and micellization of 4C_nSAZs are inclined to occur with the increase of alkyl chain length or temperature. For 4C₁₂SAZs, there are only small-size aggregates (micelles), while the large aggregates (vesicles) are observed at the alkyl length of 4C_nSAZs of 14 or 16. This shows that the alkyl chain length for oligomeric surfactants has a greater sensitivity for aggregate growth. The aggregate morphologies obtained from the calculated values of critical packing parameter (p) for 4C₁₄SAZs and 4C₁₆SAZs can be supported by the DLS measurement results. The test results obtained by the separation-water-time method show that 4C_nSAZs have good emulsification performance and that the prepared emulsions appear to exit in the form of multiple emulsions. In addition, 4C_nSAZs have good antibacterial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The present study reveals the unique behavior of a zwitterionic tetrameric surfactant and may give new insights into molecular design and synthesis of a high degree of surfactants with different structure characteristics for potential application in various industrial fields. Full article

(This article belongs to the Special Issue Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery)

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13 pages, 5392 KiB

Open AccessArticle

Interfacial Rheological Investigation of Modified Silica Nanoparticles with Different Alkyl Chain Lengths at the n-Octane/Water Interface

by Long Xu, Shijie Wen, Qiuyu Xie, Fangning Fan, Qiang Wang, Xuehao Zhang, Kaihe Lv, Han Jia and Hai Sun

Molecules 2024, 29(16), 3749; https://doi.org/10.3390/molecules29163749 - 7 Aug 2024

Viewed by 804

Abstract

The interfacial dilational rheology of silica nanoparticles (NPs) directly reflects the relationship between surface structure and interfacial behaviors in NPs, which has attracted significant attention in various industrial fields. In this work, modified silica nanoparticles (MNPs) with various alkyl chain lengths were synthesized and systematically characterized using Fourier transform infrared spectra, Zeta potential, and water contact angle measurements. It was found that the MNPs were successfully fabricated with similar degrees of modification. Subsequently, the interfacial behaviors of the MNPs in an n-octane/water system were investigated through interfacial dilational rheological experiments. The length of the modified alkyl chain dominated the hydrophilic–lipophile balance and the interfacial activity of the MNPs, evaluated by the equilibrium interfacial tension (IFT) variation and dilational elasticity modulus. In the large amplitude compression experiment, the balance between the electrostatic repulsion and interfacial activity in the MNPs was responsible for their ordered interfacial arrangement. The MNPs with the hexyl alkyl chain (M6C) presented the optimal amphipathy and could partly overcome the repulsion, causing a dramatic change in surface pressure. This was further confirmed by the variations in IFT and dilational elasticity during the compression path. The study provides novel insights into the interfacial rheology and interactions of functionally modified NPs. Full article

(This article belongs to the Special Issue Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery)

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23 pages, 7049 KiB

Open AccessArticle

A Comparative Study of Surfactant Solutions Used for Enhanced Oil Recovery in Shale and Tight Formations: Experimental Evaluation and Numerical Analysis

by Weidong Chen, Xiangfei Geng, Bin Ding, Weidong Liu, Ke Jiang, Qinglong Xu, Baoshan Guan, Lin Peng and Huan Peng

Molecules 2024, 29(14), 3293; https://doi.org/10.3390/molecules29143293 - 12 Jul 2024

Viewed by 1322

Abstract

Applying chemical enhanced oil recovery (EOR) to shale and tight formations is expected to accelerate China’s Shale Revolution as it did in conventional reservoirs. However, its screening and modeling are more complex. EOR operations are faced with choices of chemicals including traditional surfactant solutions, surfactant solutions in the form of micro-emulsions (nano-emulsions), and nano-fluids, which have similar effects to surfactant solutions. This study presents a systematic comparative analysis composed of laboratory screening and numerical modeling. It was conducted on three scales: tests of chemical morphology and properties, analysis of micro-oil-displacing performance, and simulation of macro-oil-increasing effect. The results showed that although all surfactant solutions had the effects of reducing interfacial tension, altering wettability, and enhancing imbibition, the nano-emulsion with the lowest hydrodynamic radius is the optimal selection. This is attributed to the fact that the properties of the nano-emulsion match well with the characteristics of these shale and tight reservoirs. The nano-emulsion is capable of integrating into the tight matrix, interacting with the oil and rock, and supplying the energy for oil to flow out. This study provides a comprehensive understanding of the role that surfactant solutions could play in the EOR of unconventional reservoirs. Full article

(This article belongs to the Special Issue Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery)

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19 pages, 6226 KiB

Open AccessArticle

Factors, Mechanisms, and Kinetics of Spontaneous Emulsification for Heavy Oil-in-Water Emulsions

by Jinhe Liu, Yao Li, Zengmin Lun, Yuhui Zhang, Pujiang Yang, Xinyu Tang and Qingxuan Zhang

Molecules 2024, 29(13), 2998; https://doi.org/10.3390/molecules29132998 - 24 Jun 2024

Cited by 1 | Viewed by 1021

Abstract

In challenging reservoirs where thermal recovery falls short, cold or chemical oil recovery methods are crucial. Spontaneous emulsification (SE), triggered by gentle disturbance, significantly enhances oil recovery. In elucidating SE mechanisms and kinetics, SE processes via direct contact between oil and aqueous phases without stirring were conducted. The effects of temperature, emulsifier concentration, pH, NaCl concentration, and the oil-to-water ratio on SE were investigated through droplet size analysis and turbidity measurements. Furthermore, the emulsification mechanism and derived emulsification kinetics based on turbidity data were obtained. The results underscore the feasibility of SE for oil–water systems, reducing viscous and capillary resistances without agitation. The emulsified oil mass increased with the temperature, pH, and aqueous-to-oil phase volume ratio while decreasing with the NaCl concentration. In this study, for GD-2 crude oil, the optimal emulsified oil amount occurred at a betaine surfactant (BetS-2) emulsifier concentration of 0.45%. Microscopic photo analysis indicated narrow particle size distributions and small droplets, which remained stable over time under various experimental conditions. A combined SE mechanism involving ultralow interfacial tension, interfacial turbulence due to Marangoni effects, and “diffusion and stranding” due to in situ emulsifier hydrophilicity, was speculated. Additionally, an analogous second-order kinetic equation for SE was proposed, indicating exceptional correlation with calculated and experimentally measured values. This study offers theoretical insight for enhancing oil recovery in chemical and cold production of heavy oil in oilfields. Full article

(This article belongs to the Special Issue Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery)

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14 pages, 2448 KiB

Open AccessArticle

Synthesis and Application of a Novel Multi-Branched Block Polyether Low-Temperature Demulsifier

by Shaohui Jiang, Qingsong Li, Botao Xu, Tao Zou, Yan Zhang, Wei Ping and Qiang Ma

Molecules 2023, 28(24), 8109; https://doi.org/10.3390/molecules28248109 - 15 Dec 2023

Cited by 3 | Viewed by 1204

Abstract

In this paper, a low-temperature thick oil demulsifier with high polarity was prepared by introducing ethylene oxide, propylene oxide block, and butylene oxide using m-diphenol as a starting agent. The main reasons for the difficulty involved in the low-temperature emulsification of extractive fluids were explained by analyzing the synthetic influencing factors and infrared spectra of the star comb polymer (PR-D2) and by analyzing the four fractions, interfacial energies, and zeta potentials of crude oils from the Chun and Gao fields. The effects of PR-D2 surfactant on the emulsification performance of crude oil recovery fluids were investigated via indoor and field experiments. The experimental results indicate that the optimal synthesis conditions for this emulsion breaker are as follows: a quality ratio of ionic reaction intermediates and meso-diphenol of R = 10:1; 1 g of the initiator; a polymerization temperature of 80 °C; and a reaction time of 8 h. Colloidal asphaltenes in the crude oil were the main factor hindering the low-temperature demulsification of the Gao oilfield’s extractive fluids, and the reason for the demulsification difficulty of the extractive fluids in the Chun oilfield is that the temperature of demulsification is lower than the wax precipitation point. The demulsification rate of the Chun oilfield’s extractive fluids reached more than 98% when the PR-D2 concentration reached 150 mg/L at 43 °C. The demulsification rate of the Gao oilfield’s extractive fluids reached more than 98% at a PR-D2 concentration of 150 mg/L at 65 °C. The field experiments show that the Chun oilfield’s extractive fluids can still demulsify after the temperature is reduced to 43 °C in winter. The emulsification temperature of the Gao oilfield’s extractive fluids was reduced from 73 °C to 68 °C, with an excellent demulsification effect. Full article

(This article belongs to the Special Issue Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery)

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13 pages, 3898 KiB

Open AccessArticle

Efficient Demulsification Performance of Emulsified Condensate Oil by Hyperbranched Low-Temperature Demulsifiers

by Shaohui Jiang, Qingsong Li, Qiang Ma, Botao Xu and Tao Zou

Molecules 2023, 28(22), 7524; https://doi.org/10.3390/molecules28227524 - 10 Nov 2023

Cited by 2 | Viewed by 1680

Abstract

Focusing on the problem of poor demulsification performance of light crude oil emulsions in low-permeability oilfields at low temperatures, the composition of the emulsion samples, clay particle size distribution, and the viscosity–temperature relationship curve of samples were analyzed. Based on the results of emulsion composition analysis and characteristics, the bottle test method was used to analyze the demulsifying effect of different commercial types of demulsifiers, revealing the demulsification mechanism. The field tests confirm the demulsification capabilities of Polyoxyethylene polyoxypropylene quaternized polyoxyolefins surfactants (PR demulsifiers). The results reveal that PR demulsifiers combine the features of decreasing the interfacial tension between oil and water and adsorbing SiO₂, allowing for quick demulsification and flocculation at low temperatures. This research serves as a theoretical and practical foundation for the study and advancement of low-temperature demulsification technology in oilfields. Full article

(This article belongs to the Special Issue Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery)

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22 pages, 9934 KiB

Open AccessArticle

Experimental Characterization and Evaluation of Crude Spiking Influence on Oil/Water Dispersed Flow in Pipe

by Hamidreza Asaadian and Milan Stanko

Molecules 2023, 28(17), 6363; https://doi.org/10.3390/molecules28176363 - 31 Aug 2023

Cited by 2 | Viewed by 1701

Abstract

This study centers around examining the impact of introducing varying (small) quantities of crude oil into mineral oil (Exxsol D60) on the resultant properties of dispersions and emulsions in oil–salty-water mixture properties such as rheology, droplet size distribution, separation duration, and interfacial tension. The experimentation encompassed bottle tests and a compact flow loop configuration featuring a 2 m horizontal pipe segment. The findings indicate that blends of oil infused with crude oil, combined with salty water at water ratios of 25% and 50%, necessitate an extended duration for separation and for the establishment and stabilization of interfaces, in contrast to mixtures of unaltered oil and saline water. To illustrate, in samples with spiking concentrations ranging from 200 to 800 ppm within a 25% water fraction, the separation period escalates from 51 s to 2 min and 21 s. Interestingly, when the water fraction increased to 75 percent, the impact of crude oil spiking on separation time was minimal. The analysis revealed that the Pal and Rhodes emulsion viscosity model yielded the most accurate predictions for the viscosity of resulting emulsions. The introduction of crude oil spiking elevated emulsion viscosity while diminishing interfacial tension from 30.8 to 27.6 mN/m (800 ppm spiking). Lastly, a comparative assessment was performed between droplet size distributions in the devised dispersed pipe flow and observed in an actual emulsion system comprising crude and salty water. Full article

(This article belongs to the Special Issue Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery)

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14 pages, 3571 KiB

Open AccessArticle

The Interfacial Dilational Rheology Properties of Betaine Solutions: Effect of Anionic Surfactant and Polymer

by Haitao Li, Chuanzhi Cui, Xulong Cao, Fuqing Yuan, Zhicheng Xu, Lei Zhang and Lu Zhang

Molecules 2023, 28(14), 5436; https://doi.org/10.3390/molecules28145436 - 16 Jul 2023

Cited by 1 | Viewed by 1637

Abstract

Interfacial dilational rheology is one of the important means to explore the interfacial properties of adsorption films. In this paper, the interfacial rheological properties of the mixed system of sulfobetaine ASB with a linear alkyl group and two anionic surfactants, petroleum sulfonate (PS) and alkyl polyoxyethylene carboxylate (AEC), were investigated by interfacial dilational rheology. The effect of the introduction of polymer hydrophobically modified polyacrylamide (HMPAM) on the interfacial properties of the mixed system was analyzed. In this experiment, the surfactant solution was used as the external phase and n-decane was used as the internal phase. A periodic sinusoidal disturbance of 0.1 Hz was applied to the n-decane droplets, and the changes of parameters such as droplet interfacial tension and interfacial area were monitored in real time with the help of a computer. The results show that the betaine ASB molecule responds to the dilation and compression of the interface through the change of ion head orientation, while the feedback behavior of petroleum sulfonate PS and AEC molecules embedded with oxygen vinyl groups in the molecule is diffusion and exchange between the interface and the bulk phase. Therefore, the interface film formed by ASB alone is higher, and the film formed by PS and AEC molecules alone is relatively lower. After adding two kinds of anionic surfactants to the betaine system, the ionic head of PS or AEC molecules will be attached to the positive center of the hydrophilic group of ASB molecules by electrostatic attraction and no longer adsorb and desorb with the interface deformation. The interfacial rheological properties of the compound system are still dominated by betaine, with higher dilational modulus and lower phase angle. When a small amount of HMPAM is added, or the content of hydrophobic monomer AMPS in the bulk phase is low, the intermolecular interaction at the interface is enhanced, the slow relaxation process is intensified, and the interfacial film strength is increased. As the content of AMPS further increases, hydrophobic blocks and surfactant molecules will form interfacial aggregates similar to mixed micelles at the oil-water interface, which will regulate the properties of the film by affecting the adsorption of surfactants at the interface. As long as the interfacial tension is the same, the properties of the interfacial film are the same. Based on the colloid interface science and the background of enhanced oil recovery, this study provides a reference for the field application of chemical flooding formulations. Full article

(This article belongs to the Special Issue Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery)

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23 pages, 4360 KiB

Open AccessReview

Research Progress in Nanofluid-Enhanced Oil Recovery Technology and Mechanism

by Qilei Tong, Zhenzhong Fan, Qingwang Liu, Sanyuan Qiao, Li Cai, Yuanfeng Fu, Xuesong Zhang and Ao Sun

Molecules 2023, 28(22), 7478; https://doi.org/10.3390/molecules28227478 - 8 Nov 2023

Cited by 4 | Viewed by 2843

Abstract

Nanofluid-enhanced oil recovery (EOR) technology is an innovative approach to enhancing oil production in oilfields. It entails the dispersion of nanoparticles within a fluid, strategically utilizing the distinctive properties of these nanoparticles (NPs) to engage with reservoir rocks or crude oil, resulting in a significant enhancement of the oil recovery rate. Despite the notable advantages of nanofluid EOR technology over conventional oil recovery methods such as binary and ternary flooding, practical implementations continue to grapple with a range of pressing challenges. These challenges encompass concerns regarding the economic viability, stability, and adaptability of nanomaterials, which pose significant barriers to the widespread adoption of nanofluid EOR technology in the oil field. To tackle these challenges, addressing the current issues may involve selecting simpler and more readily available materials coupled with straightforward material modification techniques. This approach aims to more effectively meet the requirements of large-scale on-site applications. Within this framework, this review systematically explores commonly employed nanofluids in recent years, including inorganic nanofluids, organic nanofluids, and composite nanofluids. It categorizes the research advancements in optimizing modification techniques and provides a comprehensive overview of the mechanisms that underpin nanofluid EOR technology and its practical applications in oilfields. This comprehensive review aims to offer valuable references and serve as a solid foundation for subsequent research endeavors. Full article

(This article belongs to the Special Issue Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery)

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