Effects of Polyether Surfactants on Dynamic Interfacial Tension of Betaine Solutions against Crude Oil

The dynamic interfacial tension (IFT) of betaine and betaine/polyether‐nonionic surfactant‐mixed systems against hydrocarbons, kerosene, and crude oil–water was studied using a spinning‐drop tensiometer. The influence of average molecular weight of polyether‐nonionic surfactants on IFT of mixed solutions was investigated. On the basis of the experimental results, one can find that it is difficult to reach the ultralow IFT value for betaine solution against hydrocarbon and kerosene because of the mismatch between the hydrophobic and hydrophilic groups. After purification, kerosene still contains a small amount of carboxyl groups, which can exert a synergistic effect on surfactants resulting in a lower IFT. The IFT of betaine and mixtures against Daqing crude oil can reach an ultralow value because of the mixed adsorption of surfactant and petroleum soap molecules. For mixed solutions, with the increasing concentration of added polyether, the decrease of petroleum soaps at the oil–water interface results in the destruction of synergistic effects.     

Synthesis of an Alkyl Polyoxyethylene Ether Sulfonate Surfactant and Its Application in Surfactant Flooding

Surfactant flooding as a potential enhanced oil‐recovery technology in a high‐temperature and high‐salinity oil reservoir after water flooding has attracted extensive attention. In this study, the synthesis of an alkyl alcohol polyoxyethylene ether sulfonate surfactant (C₁₂EO₇S) with dodecyl alcohol polyoxyethylene ether and sodium 2‐chloroethanesulfonate monohydrate, and its adaptability in surfactant flooding were investigated. The fundamental parameters of C₁₂EO₇S were obtained via surface tension measurement. And the ability to reduce oil–water interfacial tension (IFT), wettability alteration, emulsification, and adsorption was determined. The results illustrated that IFT could be reduced to 10^?3 mN m^?1 at high temperature and high salinity without additional additives, and C₁₂EO₇S exhibited benign wettability alternate ability, and emulsifying ability. Furthermore, the oil‐displacement experiments showed that C₁₂EO₇S solution could remarkably enhance oil recovery by 16.19% without adding any additives.     

Surfactant (in situ)–Surfactant (Synthetic) Interaction in Na2CO3/Surfactant/Acidic Oil Systems for Enhanced Oil Recovery: Its Contribution to Dynamic Interfacial Tension Behavior

The effect of synthetic surfactant molecular structure on the dynamic interfacial tension (DIFT) behavior in Na₂CO₃/surfactant/crude oil was investigated. Three surfactants, a nonionic (iC₁₇(EO)₁₃), an alcohol propoxy sulfate (C_14–15(PO)₈SO₄), and sodium dodecyl sulfate (SDS) were considered in this study. Sodium tripolyphosphate (STPP) was added to ensure complete compatibility between brine and Na₂CO₃. In Na₂CO₃/iC₁₇(EO)₁₃/oil and Na₂CO₃/C_14–15(PO)₈SO₄/oil systems, a strong synergistic effect for lowering the dynamic interfacial tension was observed, in which the dynamic IFT are initially reduced to ultralow transient minima in the range 1.1 × 10^?3–6.6 × 10^?3 mNm^?1 followed by an increment to a practically similar equilibrium value of 0.22 mNm^?1 independent of Na₂CO₃ concentration (for iC₁₇(EO)₁₃) and to decreasing equilibrium values with increasing alkali concentrations (for C_14–15(PO)₈SO₄). The observed difference in the equilibrium IFT for the two systems suggest that in both systems, the mixed interfacial film is efficient in reducing the dynamic interfacial tension to ultralow transient minima (～10^?3 mNm^?1) but the mixed film soap‐iC₁₇(EO)₁₃ is much less efficient than the mixed film soap‐C_14–15(PO)₈SO₄ in resisting soap diffusion from the interface to the bulk phases. In both systems, the synergism was attributed, in part, to the intermolecular and intramolecular ion–dipole interactions between the soap molecules and the synthetic surfactant as well as to some shielding effect of the electrostatic repulsion between the carboxylate groups by the nearby ethylene oxide (13 EO) and propylene oxide (8 PO) groups in the mixed interfacial monolayer. SDS surfactant showed a much lower synergism relative to iC₁₇(EO)₁₃ and C_14–15(PO)₈SO₄, probably due to the absence of ion–dipole interactions and shielding effect in the mixed interfacial layer at the oil–water interface.     

Adsorption Behavior of Fatty Alcohol Ether Sulfonate at Different Interfaces

The equilibrium surface tension, dynamic surface tension, and interfacial tension (IFT) of fatty alcohol ether sulfonates (C_mE_nSO) were measured to investigate their adsorption behavior. The effect of NaCl and CaCl₂ concentrations on the IFT was also studied. The results showed that the number of EO units has no significant effect on the critical micelle concentration (CMC) and CMC decreases with increasing the length of the hydrophobic group. The surface tension at the CMC increases with the increase of the number of EO units and the length of the hydrophobic group. At dilute surfactant concentration, the adsorption process for C_mE_nSO is controlled by diffusion; at higher concentration, it becomes a mixed diffusion‐kinetic adsorption mechanism. The IFT between C_mE_nSO solution and dodecane remains around 10^?1 mN/m over a wide range of electrolyte concentrations (NaCl concentration from 25 to 210 g/L, CaCl₂ concentration from 0.1 to 10 g/L).     

Formulation of ultralow interfacial tension systems using extended surfactants

Inspired by the concept of lipophilic and hydrophilic linkers, extended surfactants have been proposed as highly desirable candidates for the formulation of microemulsions with high solubilization capacity and ultralow interfacial tension (IFT), especially for triglyceride oils. The defining characteristic of an extended surfactant is the presence of one or more intermediate-polarity groups between the hydrophilic head and the hydrophobic tail. Currently only limited information exists on extended surfactants; such knowledge is especially relevant for cleaning and separation applications where the cost of the surfactant and environmental regulations prohibit the use of concentrated surfactant solutions. In this work, we examine surfactant formulations for a wide range of oils using dilute solutions of the extended surfactant classes sodium alkyl polypropyleneoxide sulfate (R-(PO) _x −SO₄Na), and sodium alkyl polypropyleneoxide-polyethyleneoxide sulfate (R-(PO) _y -(EO) _z −SO₄Na). The IFT of these systems was measured as a function of electrolyte and surfactant concentration for polar and nonpolar oils. The results show that these extended surfactant systems have low critical micelle concentrations (CMC) and critical microemulsion concentrations (CμC) compared with other surfactants. We also found that the unique structure of these extended surfactants allows them to achieve ultralow IFT with a wide range of oils, including highly hydrophobic oils (e.g., hexadecane), triolein, and vegetable oils, using only ppm levels of these extended surfactants. It was also found that the introduction of additional PO and EO groups in the extended surfactant yielded lower IFT and lower optimum salinity, both of which are desirable in most formulations. Based on the optimum formulation conditions, it was found that the triolein sample used in these experiments behaved as a very polar oil, and all other vegetable oils displayed very hydrophobic behavior. This unexpected triolein behavior is suspected to be due to uncharacterized impurities in the triolein sample, and will be further evaluated in future research.     

Novel Alkyl Ether Sulfonates for High Salinity Reservoir: Effect of Concentration on Transient Ultralow Interfacial Tension at the Oil–Water Interface

The effect of surfactant concentration on the occurrence and detection of transient ultralow interfacial tension (IFT) between crude oil and formation water at 75 °C has been investigated using a series of novel sodium alkyl ether sulfonates having various increasing molecular weights and degrees of ethoxylation. All surfactant systems displayed dynamic interfacial tension (DIT). Transient ultralow DIT (DIT_min) were detected only within an intermediate surfactant concentration. This behavior was attributed to an implicit concentration-related length scale required for the added surfactant to diffuse from the bulk phase to the freshly prepared oil–water interface. In the high surfactant concentration range, this length scale is relatively short and results in an instantaneous (and undetectable) occurrence of DIT_mim in a relatively very short time scale, well beyond the detection limit of the spinning drop tensiometer (~2–3 min). Interestingly, DIT_min were detected only in systems above the surfactant’s critical micelle concentration, suggesting that DIT_min occurs as a result of the diffusion (subsequent to the adsorption) of the oil acidic species from the interface to the bulk phase to form mixed micelles with the added surfactant. Measurements of DITs in the presence of decane showed no evidence for DIT_min, confirming the general belief that DIT_min is indeed due to the interaction of the added surfactant with the oil acidic components. Finally, the effect of surfactant concentration on the equilibrium IFT (γ_eq) showed evidence for relatively low values (~10⁻² mNm⁻¹) for some surfactant systems.     

Polymeric surfactants for enhanced oil recovery. Part III—interfacial tension features of ethoxylated alkylphenol-formaldehyde nonionic surfactants

The interfacial tensions (IFT) of four low molecular weight groups of ethoxylated octylphenol-, dodecylphenol-, tetradecylphenol- and hexadecyl-phenol—formaldehyde polymeric surfactants were determined using the spinning drop method. Some noteworthy features of the interfacial behaviour of dilute aqueous solutions of 16 of these compounds and homologous hydrocarbons are discussed. An important feature is that these surfactants behave similarly to monomeric ones in their hydrocarbon scan, that is they have a minimum IFT value against a particular member of a homologous hydrocarbon series. The magnitudes of the tension at minimum (γ_min) values obtained in this study are of the order of ‘ultralow’ (10^?2-10^?3 mNm^?1). The n_min values of these polymeric nonionic surfactants decrease with increasing hydrophilicity, that is decrease with the increase of ethylene oxide units condensed per mole of alkylphenol unit in the polymeric surfactants studied. In this case, the downward shift in n_min is smaller and apparently not linearly related to the number of EO units. Increasing the hydrophobicity of these polymeric nonionics, that is increasing the length of the alkyl chain from C₈ to C₁₆, resulted in an increase in the n_min values obtained. For each of the investigated groups, the lowest γ_min values are obtained with polymeric surfactants having the highest EO content. The optimum low tension performance occurs at the low end of the equivalent alkane carbon number scale (at EACNs below 6). Under the influence of added electrolytes these EACNs were shifted to higher values.     

Interfacial properties of cationic and anionic Gemini surfactant mixtures

The possibility and the prospect of cationic/anionic (“catanionic”) surfactant mixtures based on sulfonate Gemini surfactant (SGS) and bisquaternary ammonium salt (BQAS) in the field of enhanced oil recovery was investigated. The critical micelle concentration (CMC) of SGS/BQAS surfactant mixtures was 5.0 × 10⁻⁶ mol/L, 1–2 orders of magnitude lower than neat BQAS or SGS. A solution of either neat SGS or BQAS, could not reach an ultra-low interfacial tension (IFT); but 1:1 mol/mol mixtures of SGS/BQAS reduced the IFT to 1.0 × 10⁻³ mN/m at 100 mg/L. For the studied surfactant concentrations, all mixtures exhibited the lowest IFT when the molar fraction of SGS among the surfactant equaled 0.5, indicating optimal conditions for interfacial activity. The IFT between the 1:1 mol/mol SGS/BQAS mixtures and crude oil decreased and then increased with the NaCl and CaCl₂ concentrations. When the total surfactant concentration was above 50 mg/L, the IFT of SGS/BQAS mixtures was below 0.01 mN/m at the studied NaCl concentrations. Adding inorganic salt reduced the charges of hydrophilic head groups, thereby making the interfacial arrangement more compact. At the NaCl concentration was above 40,000 mg/L, surfactant molecules moved from the liquid–liquid interface to the oil phase, thus resulting in low interfacial activity. In addition, inorganic salts decreased the attractive interactions of the SGS/BQAS micelles that form in water, decreasing the apparent hydrodynamic radius (D_{H, app}) of surfactant aggregates. When the total concentration of surfactants was above 50 mg/L, the IFT between the SGS/BQAS mixtures and crude oil decreased first and then increased with time. At different surfactant concentrations, the IFT of the SGS/BQAS mixtures attained the lowest values at different times. A high surfactant concentration helped surfactant molecules diffuse from the water phase to the interfacial layer, rapidly reducing the IFT. In conclusion, the cationic-anionic Gemini surfactant mixtures exhibit superior interfacial activity, which may promote the application of Gemini surfactant.     

Thermodynamic Parameters and Interfacial Properties of Poly(ethylene glycol)-octyl Sulfosuccinates

Surface tension of a series of poly(ethylene glycol)-octyl sulfosuccinates at different temperatures was measured, and the interfacial properties were investigated in the absence and presence of inorganic salts. Surface tension results indicate that critical micelle concentration (CMC) values of five surfactants (C8-PEG200, C8-PEG400, C8-PEG600, C8-PEG800, and C8-PEG1000) decrease as the molecular weight of polyethylene glycol (PEG) segments and the experimental temperature increases. The surface activity of the C8-PEG series changes with temperature, and the surface tension at the CMC (γ_CMC) of the C8-PEG series decreases initially and then increases as the PEG molecular weight increases. This behavior may be attributed to the dehydration of the surfactant molecules, resulting in the change of hydrophile–lipophile balance for the different EO numbers in the surfactant molecules, which form a different surface energy film at the air–water interface. Negative ΔG_m indicates that the micellization process of these surfactants is spontaneous and an entropically driven process. For the water/alkane interface, these surfactants have low interfacial activity. The interfacial tension (IFT) between these surfactants and alkanes increases first and then decreases with the increase in the molecular weight of PEG segments. After the addition of salt, the interfacial activity of the investigated surfactants increases significantly. The IFT between C8-PEG800 and 10–12 alkanes and between C8-PEG1000 and 12–16 alkanes reaches a low IFT magnitude of 10⁻² mN m⁻¹ in the presence of 0.5% CaCl₂ or the mixed inorganic salts 0.5% NaCl+0.5% CaCl₂.     

A Star-Shaped Anionic Surfactant: Synthesis,Alkalinity Resistance,Interfacial Tension and Emulsification Properties at the Crude Oil–Water Interface

In this research, a star‐shaped surfactant was synthesized through the chlorination reaction, alkylation reaction and sulfonation reaction of triethanolamine, which is composed of three hydrophobic chains and three sulfonate hydrophilic groups. The critical micelle concentration (CMC) of the surfactant was measured by the surface tension method, and the results showed that it had high surface activity with CMC of 5.53 × 10^?5 mol/L. The surfactant was superior in surface active properties to the reference surfactants SDBS and DADS‐C₁₂. The interfacial tension (IFT) of the studied crude oil–water system (surfactant concentration 0.1 g/L, NaOH concentration 0.5 g/L, and experimental temperature 50 °C) dropped to 1.1 × 10^?4 mN/m, which can fulfil the requirement of surfactants for oil displacement. An aqueous solution of the surfactant and crude oil was emulsified by shaking, which formed a highly stable oil‐in‐water (O/W) emulsion with particle size of 5–20 μm. The oil displacement effect was almost 12%.     

Preparation and Performance Evaluation of Fatty Amine Polyoxyethylene Ether Diethyl Disulfonate for Enhanced Oil Recovery in High‐Temperature and High‐Salinity Reservoirs

To enhance oil recovery in high‐temperature and high‐salinity reservoirs, a novel fatty amine polyoxyethylene ether diethyl disulfonate (FPDD) surfactant with excellent interfacial properties was synthesized. The interfacial tension (IFT) and contact angle at high temperature and high salinity were systematically investigated using an interface tension meter and a contact angle meter. According to the experimental results, the IFT between crude oil and high‐salinity brine water could reach an ultra‐low value of 10^?3 mN m^?1 without the aid of extra alkali at 90°C after aging. The FPDD surfactant has strong wettability alternation ability that shifts wettability from oil‐wet to water‐wet. The FPDD surfactant with a high concentration also has good emulsion ability under high‐temperature and high‐salinity conditions. Through this research work, we expect to fill the lack of surfactants for high‐temperature and high‐salinity reservoirs and broaden its great potential application area in enhanced oil recovery.     

Salt-Induced Constructions of Gemini-like Surfactants at the Interface and Their Effects on the Interfacial Tension of a Water/Model Oil System

It is an urgent issue to enhance oil recovery for unconventional reservoirs with high salinity. Focused on this topic, salt addition is a powerful tool to motivate the surfactant assembly at the water/oil interface and improve the interfacial activity. We used a cationic surfactant cetyltrimethylammonium bromide (CTAB) and an anionic salt dicarboxylic acid sodium (CnDNa) to construct gemini-like surfactants at the interface and evaluated their ability to reduce the interfacial tension (IFT) between model oil (toluene and n-decane, v:v = 1:1) and water. Interestingly, the fabrication of a (CTAB)₂/C4DNa gemini-like surfactant was hardly achieved at the fresh water/model oil interface, but accomplished at the brine/model oil interface. At a high NaCl concentration (100,000 mg L⁻¹), the IFT value is reduced to 10⁻³ mN m⁻¹ order of magnitude, which is generally desired in practical applications. The control experiments displacing the surfactant type and the spacer length further confirmed the NaCl effects on the interfacial assembly.     

Effects of branching in hexadecylbenzene sulfonate isomers on interfacial tension behavior in oil/alkali systems

This paper is concerned with the study of the effect of the molecular structure of surfactant on the reduction of interfacial tension of Enhanced Oil Recovery (EOR). The interfacial tension behavior of nonane and crude oil with three hexadecylbenzene sulfonate isomers (with benzene rings located at different positions along the alkyl chains) were investigated. It was found that the interfacial tensions could be reduced to ultra-low values at low alkali concentrations by using a surfactant molecule with a phenyl group located near the center of the alkyl chain. Molecular structures of this kind were considered to be the most ideal for surfactant flooding. Moreover, the transient low interfacial tensions in crude oil/alkali system were caused by the synergistic effects between surfactant and the active species generated at interface, but surfactant molecules played the dominant role at equilibrium.     

Laboratory Study on the Oil Displacement Properties of Sugar Amine Sulfonate Surfactant

A sugar amine sulfonate surfactant (SAS) was used to enhance oil recovery by chemical flooding. The interfacial tension between an SAS solution and four kinds of crude oil was determined. Oil (4) containing the largest amount of medium chain length components was the most suitable candidate because the IFT could be reduced to an ultralow range (10^?3 mN/m) at optimum NaCl concentration. Emulsions consisting of oil (4) and SAS solution and the adsorption density of SAS on sandstone were studied. Compared with A37 (alkyl ether sulfate), SAS ws able to form more stable emulsions and the adsorption density was equivalent in the typical concentration range of chemical flooding. Both SAS and A37 adsorption data on sandstone followed the Langmuir isotherm model. SAS increased the apparent viscosity of KY-1500 (modified polyacrylamide) in a low concentration range and improve the viscoelasticity. A combination of SAS and KY-1500 (SP) enhanced oil recovery by 16.05 versus 14.31% (using KY-1500 alone).     

表面活性剂同系物体系对原油界面张力的影响

分别从表面活性剂的亲油性和亲水性的二种性能 ,研究了复配型表面活性剂的性能及规律。在表面活性剂同系物复配的研究中 ,得出相对分子质量分布窄的表面活性剂不能与原油形成低的界面张力 ,但两种以上相对分子质量分布窄的表面活性剂按一定比例混合后 ,则可以与大庆原油形成超低界面张力。形成超低界面张力的表面活性剂平均当量范围为 410～ 430 ,相对分子质量、碱浓度和界面张力三者之间有一定规律 ,即表面活性剂平均相对分子质量增加 ,界面张力曲线向低浓度碱方向移动 ;平均相对分子质量降低 ,界面张力曲线向高浓度碱方向移动。相对分子质量分布是影响界面张力的又一因素 ,表面活性剂相对分子质量分布、原油中的碳数分布和界面张力可能存在某种特定联系。支链对降低界面张力方面比直链有更好的效果 ,表面活性剂相对分子质量越高 ,则油砂对其吸附量越大     

Influence of polymer on dynamic interfacial tensions of EOR surfactant solutions

The effects of different types of polymers, partially hydrolyzed polyacrylamide (HPAM) and hydrophobically modified polyacrylamide (HMPAM), on dynamic interfacial tensions (IFTs) of surfactant/model oil systems have been investigated by the spinning drop method in this article. Two anionic surfactants, 1,2‐dihexyl‐4‐propylbenzene sulfonate (366), 1,4‐dibutyl‐2‐nonylbenzene sulfonate (494) and an anionic–nonionic surfactant octyl‐[ω‐alkyloxy‐poly(oxyethylene)]yl‐benzene sulfonates (828) with high purity were selected as model surfactants. The influences of polymer concentration on IFT were expounded. It was found that the addition of polymer mostly results in increasing IFT because the interfacial molecular arrangement is modified owing to the interaction between polymer and surfactants. For HPAM, the polymer chains will enter the surfactant adsorption layer to form mixed‐adsorption layer. Therefore, HPAM shows strong effect on surfactant molecules with large size, such as 366. Conversely, surfactants can interact with the hydrophobic blocks of HMPAM and form mixed micelle‐like associations at interface. As a result, HMPAM shows more impact on IFT of 494 due to small steric hindrance for the formation of interfacial associations. This mechanism has been ensured by 828 molecules with two long alkyl chains. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40562.     

Tuning the polydispersity of alcohol ethoxylates for enhanced oily soil removal

Commercially available alkyl alcohol ethoxylates have a broad distribution of ethylene oxide (EO) units and also a somewhat narrower distribution of alkyl chain length. Generally, the purer the surfactant sample (narrower distribution), the better is its detergency performance, and detergency peaks at the phase inversion temperature (PIT) for a given oil. However, in real detergency processes this may not hold true since soils are typically mixtures of several oily components, and temperature variations are significant. Therefore, if a polydispersity index (PDI) of ethoxylates is defined as the ratio of weight average EO moles to number average EO moles in the sample, then it is conceivable that an optimal PDI might be obtained. We compared the detergency of hexadecane for pentaethylene glycol monododecyl alcohol (C₁₂EO₅) samples in a broad PDI range, using an oil-soluble dye. While detergency at 55°C (PIT of hexadecane with C₁₂EO₅) decreases monotonically with increasing creasing PDI, average detergency over a 20°C temperature range around the PIT tends to show a maximum at PDI of ca. 1.1 (narrow-range ethoxylate). Similarly, for a mixture of undecane/hexadecane/tetracosane (30∶50∶20 w/w/w) for which the average PIT is approximately the same as that of hexadecane detergency at 55°C shows a maximum as a function of PDI at a value of ∼1.37 (broad-range ethoxylate). All detergency results are in general agreement with the reverse trends in oil/water interfacial tension and suggest that, having decided the optimal EO moles for a given application based on PIT, one can further improve the performance of alcohol ethoxylates in real detergency processes by tuning their polydispersity.     

碱对重烷基苯磺酸盐和无酸油相间界面张力的影响

以不含酸性物质的脱酸直馏柴油作为油相,研究了NaOH对重烷基苯磺酸盐/油体系界面张力的影响.结果表明,NaOH与原油中的石油酸反应生成自表面活性剂并不是油/水界面张力降低的主控因素.NaOH可以改变重烷基苯磺酸盐体系的最小烷烃碳数,从而影响界面张力,使界面张力达到超值.     

Surfactant Enhanced Oil Recovery in a High Temperature and High Salinity Carbonate Reservoir

The goal of this work was to find an effective surfactant system for enhanced oil recovery after water injection substituting for oil at a vuggy fractured reservoir with a high temperature and high salinity (220,000 mg/L). Four types of surfactants with concentrations (less than 0.2 %) were screened. Washing oil experiments were conducted in Amott cells. A surfactant system was established by mixing a surfactant with best ultimate recovery and one with best recovery rate. The optimized surfactant system could recover 50 % of remaining oil. To study the mechanism of enhanced oil recovery after water injection substituting oil, interfacial tension (IFT) and contact angle were measured. Experimental results showed that surfactants with good washing ability had low IFT, but surfactants with low IFT may not have a good washing ability. IFT had no obvious relationship with the increased oil recovery or washing ability. The optimized system could not alter carbonate to decrease the oil‐wetting capability. Though octadecyl trimethyl ammonium chloride had a good ability wet the carbonate with water, it could not recover much oil. Therefore, except for interfacial tension and wettability alteration, there must be other parameters dominating oil recovery after water injection substituting for oil.     

Novel fluorinated surfactants for enhanced oil recovery in carbonate reservoirs

Novel surfactant‐polymer (SP) formulations containing fluorinated amphoteric surfactant (surfactant‐A) and fluorinated anionic surfactant (surfactant‐B) with partially hydrolyzed polyacrylamide (HPAM) were evaluated for enhanced oil recovery applications in carbonate reservoirs. Thermal stability, rheological properties, interfacial tension, and adsorption on the mineral surface were measured. The effects of the surfactant type, surfactant concentration, temperature, and salinity on the rheological properties of the SP systems were examined. Both surfactants were found to be thermally stable at a high temperature (90 °C). Surfactant‐B decreased the viscosity and the storage modulus of the HPAM. Surfactant‐A had no influence on the rheological properties of the HPAM. Surfactant‐A showed complete solubility and thermal stability in seawater at 90 °C. Only surfactant‐A was used in adsorption, interfacial tension, and core flooding experiments, since surfactant‐B was not completely soluble in seawater and therefore was limited to deionized water. A decrease in oil/water interfacial tension (IFT) of almost one order of magnitude was observed when adding surfactant‐A. However, betaine‐based co‐surfactant reduced the IFT to 10^?3 mN/m. An adsorption isotherm showed that the maximum adsorption of surfactant‐A was 1 mg per g of rock. Core flooding experiments showed 42 % additional oil recovery using 2.5 g/L (2500 ppm) HPAM and 0.001 g/g (0.1 mass%) amphoteric surfactant at 90 °C.