Mechanism of Wettability Alteration of an Oil-Wet Sandstone Surface

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Mechanism of wettability alteration of oil-wet sandstone surface by a novel cationic gemini surfactant Baofeng Hou, Ruixiu Jia, Meilong Fu, Youqing Huang, and Yefei Wang Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.9b00304 • Publication Date (Web): 01 Apr 2019 Downloaded from http://pubs.acs.org on April 2, 2019

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Mechanism of wettability alteration of oil-wet sandstone surface by a novel cationic gemini surfactant Baofeng Houa,*, Ruixiu Jiab, Meilong Fua, Youqing Huanga, Yefei Wangc aSchool

of Petroleum Engineering, Yangtze University, Wuhan 430100, China

bWuhan

campus, Yangtze University, Wuhan 430100, China

cSchool

of Petroleum Engineering, China University of Petroleum (East China),

Qingdao 266580, China

Abstract A novel cationic gemini surfactant was prepared by chlorination and quaternization in this paper. The target product was successfully synthesized, which was confirmed by IR (infrared) spectrometer and NMR (nuclear magnetic resonance) analysis. Different methods including zeta potential determination, SEM (scanning electron microscope), IR, sessile drop method and spontaneous imbibition were used to investigate the mechanism of wettability alteration of oil-wet surface by the synthesized gemini surfactant (product number: GABEO) in this work. Results show that the gemini surfactant has excellent surface activity (32.5 mN/m). “Ion pair formation” is responsible for the mechanisms of wettability alteration of oil-wet sandstone surface by

GABEO,

dodecyltrimethylammonium

bromide

(DTAB)

and

di-dodecyltrimethylammonium bromide (GDTAB). Due to better wettability alteration ability of the synthesized gemini surfactant, there are fewer asphaltene particles on the solid surface treated with GABEO. Compared with DTAB and the ∗ Corresponding

author. E-mail address: [email protected] (B. Hou).

ACS Paragon Plus Environment

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traditional gemini surfactant GDTAB, lower balanced contact angle was obtained for GABEO due to the stronger ion pair desorption capacity, i.e., GABEO has a stronger ability to change wettability of oil-wet sandstone surface. In addition, owing to the strongest ability to change the surface wettability, the core has the largest ultimate imbibition recovery among the three systems when using GABEO. Keywords: Cationic gemini surfactant; Infrared analysis; Scanning electron microscope; Wettability alteration; Oil-wet sandstone surface

1 Introduction At present, oil recoveries in oil fields around the world are generally very low, and a large number of physical and chemical methods have been used to improve oil recoveries

1-8.

Reservoir wettability has a large effect on the distribution of fluids in

the reservoir, further greatly affecting oil recoveries

9, 10.

If the oil-wet rock surface

can be changed to be a water-wet surface, the oil recovery will be greatly improved. Among the reagents used in oilfield development, the wettability of rock surfaces can be effectively changed by surfactants, especially the gemini surfactants

11-13.

The

gemini surfactant shows better performance at many aspects than the traditional surfactants, especially the ability to change rock wettability. In order to obtain higher wettability change ability, one method was used to prepare a novel zwitterionic gemini surfactant in this paper. Double quaternary ammonium surfactant is the most important cationic gemini surfactant, which has a simple molecular structure, low critical micelle concentration, good emulsifying property and solubilizing performance, et al


14, 15.

Nonionic gemini

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surfactants mainly include two types: polyoxyethylene ether type or polypropylene ether type, which have the advantages of strong salt resistance, low critical micelle concentration, and good resistance to multivalent cations. In addition, related research of amphiphilic gemini surfactants has been mainly focused on the study of anionic-cationic and anionic-nonionic gemini surfactants in the past few years

16-19.

There are few reports on the study of cationic gemini surfactants. Therefore, a nonionic group (polyoxyethylene ether) and a quaternary ammonium salt molecule structure were combined to synthesize a novel surfactant in this paper, which can simultaneously have the advantages of both cationic and nonionic surfactants. Currently, various experimental methods have been used to conduct a lot of research on the mechanism of wettability change of oil-wet solids by surfactants 20-22. Different methods were used to study the mechanism of cationic surfactants to change wettability of oil-wet surface by Jarrahian et al 23. The experimental results show that an ion pair is formed by the cationic surfactant C12TAB and the carboxylic substance in the crude oil and the ion pair is further desorbed from the rock surface, exposing a clean water-wet surface. Salehi et al.

24

found that if the ion‐pair formation is

responsible for the mechanism of changing oil-wet surface by cationic surfactants, the ability of cationic surfactants to change wettability of oil-wet surface can be enhanced by increasing the amount of positive charge of surfactants. Thus, the ultimate spontaneous imbibition recovery of the core can be greatly enhanced. There are few studies on how to change the wettability of oil-wet sandstone by cationic gemini surfactants. A novel cationic gemini surfactant was prepared by the


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two steps of chlorination and quaternization with fatty alcohol polyoxyethylene ether, thionyl chloride and tetramethylethylenediamine in this paper. Different micro and macro methods including zeta potential measurement, SEM measurement, contact angle measurement and spontaneous imbibition experiments were employed to explore the microscopic mechanism of wettability change of oil-wet sandstone surface by the target product (GABEO).

2 Experimental 2.1 Materials 2.1.1 Solid materials Quartz glass and quartz sand used in this paper were purchased from Shanghai Jingjing Glass Instrument Factory (Shanghai, China). The mesh of the used quartz sand was 200 mesh and the density of the quartz sand was 2.65 g/cm3. In addition, the effective content of SiO2 of the quartz sand was 99.3% in this paper. The cores used in the spontaneous imbibition experiment were purchased from Southwest Petroleum University (Chengdu, China). Related parameters are shown in Table 1. 2.1.2 Reagents The reagents used in this work including sodium chloride, calcium chloride, magnesium chloride, thionyl chloride, tetramethylethylenediamine (TMEDA) and potassium bromide are all analytically pure and were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). What’s more, sodium chloride, calcium chloride and magnesium chloride were used to prepare the simulated formation water in this study. Ion components of the formation water used in the


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following studies are shown in Table 2. In addition, the formation water was used to prepare the various solutions used subsequently in this work. 2.1.3 Surfactants Dodecyl alcohol polyoxyethylene ether (AEO) was used to prepare the cationic gemini surfactant (GABEO) in the present study. AEO, dodecyltrimethylammonium bromide (DTAB) and di-dodecyltrimethylammonium bromide gemini surfactant (product number: GDTAB) are chemically pure and were purchased from Hubei Jusheng Technology Co., Ltd. (Wuhan, China). 2.1.4 Oil phase The crude oil used in this paper was obtained from Changqing Oilfield, China. The density, viscosity and acid number of the used crude oil are 0.75 g/cm3, 60.8 mPa·s and 1.55 mg of KOH/g, respectively. 2.2 Methods 2.2.1 Synthesis of the gemini surfactant AEO was employed to prepare the target product (GABEO) in this study (Fig. 1). During the synthesis process, thionyl chloride was used as a chlorination reagent and the intermediate was obtained by the chlorination reaction (nAEO: nSOCl2=2:3, temperature: 80 °C, time: 8 h, catalyst: pyridine). The target product GABEO were subsequently obtained by quaternization reaction (nintermediate: n

TMEDA

=2:1,

temperature: 80 °C, time: 3 d) (Fig. 1). In addition, the purity of the crude product without purification was maintained at about 90%, while the purity of the purified product used for characterization and mechanistic analysis was 99.1% in this work.


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2.2.2 Structural characterization of reaction products PerkinElmer Frontier IR spectrometer (Waltham, USA) was used to obtain the IR spectrum using the KBr tableting method in this paper. The target product was dissolved with deuterated heavy water (D2O), and the 1HNMR spectrum was measured using the Thermo Fisher picoSpin 80 NMR spectrometer (Massachusetts, USA). 2.2.3 Surface tension measurement Kono A601 Surface tension meter (Boston, USA) was used to measure the surface tension of different solutions through the hanging plate method at ambient temperature in the present study

25.

The critical micelle concentrations of different

surfactants can be analyzed from the surface tension curve 25. 2.2.4 Contact angle measurement Sessile drop method was utilized to determine the contact angles of various systems using the DSA20 contact angle meter (Hamburg, Germany) at room temperature (25℃) in this paper

26.

Quartz plate was used to simulate sandstone surface in this

paper. The quartz plates were first immersed in the chromic acid for 24 h. After the acid treatment, the quartz plates were cleaned by deion-ized water. The quartz plates were then placed into the oil phase and treated in a drying oven at 75℃ for 5 days. The quartz plates were cleaned with n-heptane and were finally dried overnight. 2.2.5 Zeta potential determination The surfactant adsorption can be reflected by the charge of the solid surface

27.

In

order to analyze the mechanisms of surfactants adsorption on solid surfaces, zeta


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potential determination was performed using Zetasizer Nano ZSP (Malvern City, UK) at ambient temperature in this study 27. 2.2.6 Spontaneous imbibition of cores Based on the related methods of the previous work, the oil-wet core was first obtained at 75℃ in this work 28. The oil-wet core was then placed into a solution-filled Amott cell for spontaneous imbibition at room temperature (25℃)

28.

The amount of crude

oil displaced by the imbibition was read from the scale on the device. Thus, the final imbibition recovery can be further calculated from the experimental results. The spontaneous imbibition experimental device is shown in Fig. 2. 2.2.7 Interfacial tension (IFT) measurement TX-500C spinning drop interfacial tensiometer (Kono, USA) was used to determine the oil-water interfacial tension at room temperature in this paper

28.

The specific

experimental results are shown in Table 3. 2.2.8 SEM determination Hitachi SU8020 field emission scanning electron microscope (Tokyo, Japan) was used to analyze the effects of different surfactants on the wettability of rock surfaces in this study, which can help us more visually analyze the mechanism of changing wettability by GABEO 29.

3 Results and discussion 3.1 Structural characterization of the synthesized surfactant To further confirm molecular structure of the target product, IR and NMR determinations were used to characterize the synthesized gemini surfactant in this


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paper. 3.1.1 Infrared measurement The functional group composition of the target product can well be revealed by the infrared spectrum. Fig. 3 shows the infrared spectra of different products. From Fig. 3 one can see that compared with the infrared absorption peaks of raw materials, hydroxy peak clearly disappeared, indicating that the chlorination reaction was successfully carried out. In addition, the absorption peaks at 2925 cm-1 and 2860 cm-1 are related to the antisymmetric stretching vibration of CH3 and the symmetric stretching vibration of CH2, respectively. The absorption peak at 1115 cm-1 corresponds to the stretching vibration peak of the ether bond C-O. While the appearance of the absorption peak at 925 cm-1 is caused by the plane rocking vibration of the intermediate polyoxyethylene ether. There is a strong absorption peak at 3445 cm-1, which corresponds to the vibration peak of hydroxyl in water. 3.1.2 NMR measurement The molecular structure of the target product was further confirmed by NMR in this work (Fig. 4). The experimental results analyzed from Fig. 4 are as follows: 1HNMR (CDCl3, TMS): δ: 0.826(t, 6H, 2CH3-CH2-); 1.226(m, 36H, 2CH3-(CH2)9-); 1.506(m, 4H,

2C10H21-CH2-CH2-O-);

3.23(s,

12H,

2-N+(CH3)2-);

3.39(t,

4H,

2C10H21-CH2-CH2-O-); 3.52(t, 4H, 2-N+-CH2-CH2-O-); 3.63(t, 64H, -(O-CH2-CH2)8-); 3.73(t, 4H, -N+CH2CH2N+-); 4.0(t, 4H, 2-N+-CH2-CH2-O-). It can be seen from the experimental results of infrared and NMR measurements that the designed target product was successfully synthesized.


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3.2 Mechanism of wettability alteration by the synthesized surfactant The synthesized target product is a cationic gemini surfactant. In general, gemini surfactants have better performance than ordinary surfactants at many aspects. Structurally, the synthesized surfactant should have stronger ability of wettability alteration of oil-wet sandstone surface. Different experimental methods were used to study wettability alteration of oil-wet sandstone surface by the target product and its mechanism in the present study. 3.2.1 Critical micelle concentration (cmc) determination Surface tension method was used to determine the critical micelle concentrations of different surfactant solutions and the corresponding surface tension (γcmc) in this paper 30.

The specific experimental results are shown in Table 4. It can be seen from Table 4

that the synthesized gemini surfactant (GABEO) has the lowest cmc among the four surfactants (AEO, DTAB, GDTAB and GABEO). In addition, the corresponding surface tension (γcmc) for GABEO is also lower than that for the traditional surfactants (AEO and DTAB) and the ordinary gemini surfactant GDTAB. Thus, the target product (GABEO) has an excellent surface activity. 3.2.2 Zeta potential determination The charge on the solid surface can indirectly reflect the surfactant adsorption. Zeta potential measurement was used to determine and analyze the effect of adsorption of various surfactants on the charges of solid surfaces in this paper 31. Fig. 5 shows the effect of surfactants on zeta potential at different concentrations. As shown in Fig. 5, the zeta potential values of solid surface for AEO gradually decrease and eventually


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reach equilibrium. While the zeta potential values of solid surfaces for DTAB, GDTAB and GABEO first increase, then decrease due to the desorption of ion pairs from the solid surface, and eventually the stable balanced values are reached. It can be seen from the comparison of the three curves (DTAB, GDTAB & GABEO) that mechanisms of wettability change behind the experimental results for DTAB, GDTAB and GABEO are all “Ion pair mechanism”

26.

Moreover, the ability to

change wettability of oil-wet sandstone surfaces for GABEO is stronger than that for DTAB and GDTAB. 3.2.3 SEM determination Mechanisms of wettability alteration of oil-wet sandstone surface by various surfactants can be analyzed by observing changes of the microscopic morphology of the solid surfaces. SEM was used to determine the microscopic morphology of solid surfaces treated with different surfactants (0.30 wt%) in this paper 32. Fig. 6 shows the SEM images of various solid surfaces. It can be seen from Fig. 6(a) that many asphaltene particles are adsorbed on the quartz surface and solid surface shows an oil-wet state. Figs. 6(b), (c), (d) and (e) show the microscopic adsorption morphology of oil-wet surfaces treated with different surfactants. Compared with Fig. 6(a), the amount of asphaltene particles on the oil-wet surface after being treated with the nonionic surfactant AEO is reduced, but there are still many asphaltene particles (Fig. 6(b)). While for the oil-wet surfaces treated with DTAB, GDTAB and GABEO, the amount of asphaltene particles on the solid surfaces is greatly reduced due to desorption of ion pairs (Figs. 6(c), (d), (e)). As can be seen from the comparison of


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Figs. 6(c), 6(d) and 6(e), due to better wettability alteration ability of the synthesized gemini surfactant, there are fewer asphaltene particles on the solid surface treated with GABEO (Fig. 6(e)). The SEM measurement results are consistent with the zeta potential measurement results, from which the effect of various surfactants on the wettability of rock surface was visually analyzed. 3.2.4 IR analysis Infrared analysis was used to further analyze the mechanism of wettability alteration of oil-wet sandstone surface by GABEO in this study. Fig. 7 shows the IR spectra of the aged (oil-wet) sandstone surface and oil-wet sandstone surface treated by AEO. It can be seen from Fig. 7(a) that many components of crude oil have been adsorbed on the sandstone surface. The absorption peaks at 759 and 1381 cm-1 correspond to the bending vibration of C-H of the benzene ring and the symmetric deformation of the saturated C-H, respectively. The absorption peak at 1691 cm-1 is related to the stretching vibration of carbonyl group (C=O). There are two absorption peaks at 2849 and 2917 cm−1, which are attributed to the stretching vibrations of alkyl group -CH2 and -CH3. Fig. 7(b) shows the IR spectrum of oil-wet sandstone surface treated by AEO. There are two peaks at 1170 and 1275 cm-1 corresponding to the stretching vibrations of the C-O group, indicating that the nonionic surfactant AEO is adsorbed on the solid surface. In addition, Fig. 7(b) shows that some components of crude oil including alkyl groups and carbonyl groups are still left on the sandstone surface, confirming the “adsorption mechanism” for the wettability alteration of oil-wet sandstone surface by AEO 26.


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Fig. 8 shows the IR spectra of different surfaces treated by DTAB, GDTAB and GABEO. The intensity of many peaks in Fig. 8 is weaker than that in Fig. 7(a), such as the absorption peaks at 1690, 2850 and 2920 cm-1 (Fig. 8), which is caused by the desorption of ion pairs formed by the cationic surfactants and carboxyl substances (“Ion pair mechanism”)

26.

Furthermore, the intensity of the above three absorption

peaks (1690, 2850 and 2920 cm-1) in the spectrum of the surface treated by DTAB is the largest one among the three IR spectra (Fig. 8). While the above three absorption peaks in the spectrum of the surface treated by GABEO have the lowest intensity and these two absorption peaks (2850 and 2920 cm-1) disappeared. From the above experimental results, we can draw a conclusion that the surfactant GABEO has the best ion-pair desorption capacity among the three cationic surfactants, i.e., GABEO has a better ability to change wettability from oil-wet condition towards water-wet state. Thus, the SEM results were well confirmed by the infrared results in this work. 3.2.5 Contact angle measurement Contact angle measurement was used to indirectly study the mechanism of wettability alteration of oil-wet sandstone surface by the gemini surfactant GABEO in this work 33.

Fig. 9 shows the effect of surfactants on contact angles at different concentrations.

In general, cationic surfactants have a stronger ability to change the wettability of oil-wet sandstone surfaces than nonionic surfactants. From Fig. 9 one can see that the ultimate equilibrium contact angles for DTAB, GDTAB and GABEO are lower than that for AEO. Compared with DTAB and GDTAB, lower contact angle was obtained for GABEO due to the stronger ion pair desorption capacity, i.e., GABEO has a


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stronger ability to change wettability of oil-wet sandstone surface. The contact angle measurement results are in agreement with the above experimental results. Fig. 10 shows the microscopic mechanism of oil droplet curling by surfactant-induced

wettability

alteration

during

the

oilfield

development.

Hydrophobic chains of the natural active substances in the reservoir face the formation water, making the rock surface oil-wet. Oil droplets will show a spreading state on such solid surface (Fig. 10(a)). The force of the oil-water-solid three phase perimeter can be analyzed by Young's equation in the presence of surfactants (Equation 1).

 so   sw   ow cos w

(1)

where σso is the crude oil-solid interfacial tension, σsw is the water-solid interfacial tension, σow is the oil-water interfacial tension and θw is the water phase contact angle 28.

On the one hand, due to the desorption of the ion pair, a clean water-wet surface is

exposed, thereby achieving a wetting reversal state. On the other hand, surfactant molecules in the formation water could be adsorbed on the oil-water interface and solid-water interface, making σow and σsw decrease. While it is difficult to diffuse to the solid-crude oil interface for the surfactant molecules, making σso stay basically unchanged. In order to maintain the balance of Young's equation, the value of cosθw will increase. Thus, the contact angle θw becomes smaller (θo becomes larger). Correspondingly, the oil droplet slowly rolls up and is easier to be displaced by the fluid, making the oil recovery significantly be improved (Fig. 10(b)). 3.2.6 Spontaneous imbibition experiments


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The spontaneous imbibition rate and ultimate recoveries of the cores in different solutions are closely related to the wettability of the solid surface. The surfactants in the solution can effectively change the wettability of the core surface, thereby affecting the spontaneous imbibition of the core 34. Therefore, spontaneous imbibition experiment of the core can be used to indirectly analyze the mechanism of wettability change of sandstone surface by various surfactants 35. Oil droplets emerged from the various surfaces of the core during the experiment, indicating that spontaneous imbibition of the core was driven by capillary force (Pc) 26. As can be seen from Table 3, the size order of capillary forces of different systems is as follows: Pc(AEO)﹥Pc(DTAB)﹥Pc(GDTAB)﹥Pc(GABEO). Fig. 11 shows the spontaneous imbibition curves of different surfactant systems (0.30 wt%). It can be seen from Fig. 11 that the final imbibition recoveries for GABEO, DTAB and GDTAB are much greater than that for AEO. Due to the strongest ability to change the surface wettability, the core for GABEO has the largest ultimate recovery among the four systems. In addition, it can also be seen from Fig. 11 that the surfactant AEO has the worst wettability change ability. Results of the spontaneous imbibition experiments are in good agreement with the results of the contact angle measurement. Thus, the mechanisms of wettability changes of oil-wet sandstone surface by various surfactants are indirectly confirmed through the spontaneous imbibition experiments. A variety of experimental methods were used to analyze the mechanism of the synthesized gemini surfactants (GABEO) to change the wettability of oil-wet sandstone surface. Fig. 12 shows the schematic diagram of the mechanism of


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wettability change by GABEO at different concentrations. No micelles are formed in the solution and ion pairs are formed on the rock surface at low and intermediate concentrations (Figs. 12(a) and 12(b)). When the surfactant concentration exceeds cmc, micelles are formed in the solution. The ion pair is desorbed from the rock surface and is solubilized into the formed micelles, exposing a clean water-wet surface (Fig. 12(c))

1-3, 36.

Thus, the originally oil-wet surface is changed to be a

water-wet surface.

4 Conclusions Various experimental methods were used to investigate the mechanism of wettability alteration of oil-wet sandstone surface by the synthesized gemini surfactant GABEO in the present study. The main conclusions are as follows: Successful synthesis of the target product GABEO was confirmed by IR and NMR analysis results. Moreover, the synthesized gemini surfactant (GABEO) has an excellent surface activity (32.5 mN/m). Mechanisms of wettability alteration behind the experimental results for DTAB, GDTAB and GABEO are all “Ion pair mechanism”. Due to better wettability alteration ability of the synthesized gemini surfactant, there are fewer asphaltene particles on the solid surface treated with GABEO. Compared with DTAB and the traditional gemini surfactant GDTAB, lower balanced contact angle was obtained for GABEO due to the stronger ion pair desorption capacity, indicating that GABEO has a stronger ability to change wettability of oil-wet sandstone surface.


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Due to the strongest ability to change the surface wettability, the core for GABEO has the largest ultimate recovery among the four systems during the spontaneous imbibition process.

Acknowledgements Thanks to the National Natural Science Foundation of China (Youth Fund) (51704036) and the Eleventh College Students’ Innovative and Entrepreneurial Training Project in Yangtze University (2018194) for the financial support. We would also like to thank the relevant researchers who provide help during the experiment.

Nomenclature NMR = nuclear magnetic resonance cmc = critical micelle concentration infrared = IR k = permeability Soi = initial oil saturation OOIP = original oil in place Pc = capillary force

References (1) Pal, N.; Saxena, N.; Mandal, A. Synthesis, characterization, and physicochemical properties of a series of quaternary gemini surfactants with different spacer lengths. Colloid Polym. Sci. 2017, 295(12), 2261-2277. (2) Pal, N.; Saxena, N.; Mandal, A. Studies on the physicochemical properties of synthesized tailor-made gemini surfactants for application in enhanced oil recovery. J.


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Mol. Liq. 2018, 258, 211-224. (3) Pal, N.; Kumar, N.; Verma, A.; Ojha, K.; Mandal, A. Performance evaluation of novel sunflower oil-based gemini surfactant(s) with different spacer lengths: application in enhanced oil recovery. Energy Fuels 2018, 32(11), 11344-11361. (4) Liu, S.; Liu, X.; Guo, Z.; Liu, Y.; Guo, J.; Zhang, S. Wettability modification and restraint of moisture re-adsorption of lignite using cationic gemini surfactant. Colloids Surf., A 2016, 508, 286-293. (5) Zhang, R.; Qin, N.; Peng, L.; Tang, K.; Ye, Z. Wettability alteration by trimeric cationic surfactant at water-wet/oil-wet mica mineral surfaces. Appl. Surf. Sci. 2012, 258 (20), 7943-7949. (6) Wever, D.; Picchioni, F.; Broekhuis, A. Polymers for enhanced oil recovery: a paradigm for structure-property relationship in aqueous solution. Prog. Polym. Sci. 2011, 36 (11), 1558-1628. (7) Lazar, I.; Petrisor, I.; Yen, T. Microbial enhanced oil recovery (MEOR). Pet. Sci. Technol. 2007, 25 (11), 1353-1366. (8) Austad, T.; Shariatpanahi, S.; Strand, S.; Black, C.; Webb, K. Conditions for a low-salinity enhanced oil recovery (EOR) effect in carbonate oil reservoirs. Energy Fuels 2011, 26 (1), 569-575. (9) Zhao, X.; Blunt, M. J.; Yao, J. Pore-scale modeling: Effects of wettability on waterflood oil recovery. J. Pet. Sci. Eng. 2010, 71 (3-4), 169-178. (10)Hendraningrat, L.; Torsæter, O. Effects of the initial rock wettability on silica-based nanofluid-enhanced oil recovery processes at reservoir temperatures.


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Energy Fuels 2014, 28 (10), 6228-6241. (11)Chang, H.; Zhang, H.; Jia, Z.; Li, X.; Gao, W.; Wei, W. Wettability of coal pitch surface by aqueous solutions of cationic Gemini surfactants. Colloids Surf., A 2016, 494, 59-64. (12)Chang, H.; Cui, Y.; Wei, W.; Li, X.; Gao, W.; Zhao, X.; Yin, S. Adsorption behavior

and

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by

Gemini

surfactants

with

ester

bond

at

polymer-solution-air systems. J. Mol. Liq. 2017, 230, 429-436. (13)Chang, H.; Cui, Y.; Wang, Y.; Li, G.; Gao, W.; Li, X.; Zhao, X.; Wei, W. Wettability and adsorption of PTFE and paraffin surfaces by aqueous solutions of biquaternary ammonium salt Gemini surfactants with hydroxyl. Colloids Surf., A 2016, 506, 416-424. (14)Migahed, M.; Shaban, M.; Fadda, A.; Ali, T. A.; Negm, N. Synthesis of some quaternary ammonium gemini surfactants and evaluation of their performance as corrosion inhibitors for carbon steel in oil well formation water containing sulfide ions. RSC Adv. 2015, 5 (126), 104480-104492. (15)Sorenson, G. P.; Mahanthappa, M. K. Unexpected role of linker position on ammonium gemini surfactant lyotropic gyroid phase stability. Soft Matter 2016, 12 (8), 2408-2415. (16)Zhou, M.; Li, S.; Zhang, Z.; Wang, C.; Luo, G.; Zhao, J. Progress in the synthesis of zwitterionic Gemini surfactants. J. Surfactants Deterg. 2017, 20 (6), 1243-1254. (17)Kanoje, B.; Padshala, S.; Parikh, J.; Sahoo, S. K.; Kuperkar, K.; Bahadur, P. Synergism and aggregation behaviour in an aqueous binary mixture of


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cationic-zwitterionic surfactants: physico-chemical characterization with molecular simulation approach. Phys. Chem. Chem. Phys. 2018, 20 (1), 670-681. (18)Zheng, Y.; Ren, Z.; Mei, P.; Yu, L. Interactions Between a Sulfobetaine‐Type Zwitterionic Gemini Surfactant and Fatty Acid Alkanolamide in Aqueous Micellar Solution. J. Surfactants Deterg. 2016, 19 (2), 283-288. (19)Geng, X. F.; Hu, X. Q.; Jia, X. C.; Luo, L. J. Effects of sodium salicylate on the microstructure of a novel zwitterionic gemini surfactant and its rheological responses. Colloid Polym. Sci. 2014, 292 (4), 915-921. (20)Salehi, M.; Johnson, S. J.; Liang, J. T. Mechanistic study of wettability alteration using surfactants with applications in naturally fractured reservoirs. Langmuir 2008, 24 (24), 14099-14107. (21) Seiedi, O.; Rahbar, M.; Nabipour, M.; Emadi, M. A.; Ghatee, M. H.; Ayatollahi, S. Atomic force microscopy (AFM) investigation on the surfactant wettability alteration mechanism of aged mica mineral surfaces. Energy Fuels 2010, 25 (1), 183-188. (22)Bera, A.; Ojha, K.; Kumar, T.; Mandal, A. Mechanistic study of wettability alteration of quartz surface induced by nonionic surfactants and interaction between crude oil and quartz in the presence of sodium chloride salt. Energy Fuels 2012, 26 (6), 3634-3643. (23)Jarrahian, K.; Seiedi, O.; Sheykhan, M.; Sefti, M. V.; Ayatollahi, S. Wettability alteration of carbonate rocks by surfactants: a mechanistic study. Colloids Surf., A 2012, 410, 1-10.


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(24)Salehi, M.; Johnson, S. J.; Liang, J. T. Enhanced Wettability Alteration by Surfactants with Multiple Hydrophilic Moieties. J. Surfactants Deterg. 2010, 13 (3), 243-246. (25)Azum, N.; Rub, M. A.; Asiri, A. M.; Bawazeer, W. A. Micellar and interfacial properties of amphiphilic drug-nonionic surfactants mixed systems: Surface tension, fluorescence and UV-vis studies. Colloids Surf., A 2017, 522, 183-192. (26)Hou, B. F.; Wang, Y. F.; Huang, Y. Mechanistic study of wettability alteration of oil-wet sandstone surface using different surfactants. Appl. Surf. Sci. 2015, 330, 56-64. (27)Coday, B. D.; Luxbacher, T.; Childress, A. E.; Almaraz, N.; Xu, P.; Cath, T. Y. Indirect determination of zeta potential at high ionic strength: specific application to semipermeable polymeric membranes. J. Membr. Sci. 2015, 478, 58-64. (28)Hou, B. F.; Wang, Y. F.; Huang, Y. Study of spontaneous imbibition of water by oil-wet sandstone cores using different surfactants. J. Dispersion Sci. Technol. 2015, 36 (9), 1264-1273. (29)Xia, W.; Ni, C.; Xie, G. The influence of surface roughness on wettability of natural/gold-coated ultra-low ash coal particles. Powder Technol. 2016, 288, 286-290. (30)Nagaraj, K.; Ambika, S.; Arunachalam, S. Synthesis, CMC determination, and intercalative binding interaction with nucleic acid of a surfactant-copper (II) complex with modified phenanthroline ligand (dpq). J. Biomol. Struct. Dyn. 2015, 33 (2), 274-288. (31)Song, J.; Zeng, Y.; Wang, L.; Duan, X.; Puerto, M.; Chapman, W. G.; Biswal, S.


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L.; Hirasaki, G. J. Surface complexation modeling of calcite zeta potential measurements in brines with mixed potential determining ions (Ca2+, CO32-, Mg2+, SO42-) for characterizing carbonate wettability. J. Colloid Interface Sci. 2017, 506, 169-179. (32)El-Hoshoudy, A.; Desouky, S.; Betiha, M.; Alsabagh, A. Use of 1-vinyl imidazole based surfmers for preparation of polyacrylamide-SiO2 nanocomposite through aza-Michael addition copolymerization reaction for rock wettability alteration. Fuel 2016, 170, 161-175. (33)Seyyedi, M.; Sohrabi, M.; Farzaneh, A. Investigation of rock wettability alteration by carbonated water through contact angle measurements. Energy Fuels 2015, 29 (9), 5544-5553. (34)Alvarez, J. O.; Schechter, D. S. Wettability alteration and spontaneous imbibition in unconventional liquid reservoirs by surfactant additives. SPE Reservoir Eval. Eng. 2017, 20 (1), 107-117. (35) Liu, Y. L.; Jin, Z. H.; Li, H. Z. Comparison of Peng-Robinson Equation of State With Capillary Pressure Model With Engineering Density-Functional Theory in Describing the Phase Behavior of Confined Hydrocarbons. SPE J. 2018, 23(5), 1784-1797. (36) Hou, B. F.; Jia, R. X.; Fu, M. L.; Wang, Y. F.; Bai, Y.; Huang, Y. Q. Wettability Alteration of an Oil-Wet Sandstone Surface by Synergistic Adsorption/Desorption of Cationic/Nonionic Surfactant Mixtures. Energy Fuels 2018, 32 (12), 12462-12468.


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Graphical Abstract Wettability alteration of oil-wet surface by stronger desorption of ion pairs formed by the gemini surfactant GABEO and carboxyl substance

σow

Ion pair

(Water)

(Oil drop) θo

σsw

θw

σso


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Energy & Fuels

Tables Table 1 Related parameters of the used cores Porosity, Core number

Length, cm

Diameter, cm

k, 10-3μm2

Soi, %

% J-1

5.16

2.50

22.45

102.10

68.10

J-2

5.13

2.50

22.39

101.95

68.05

J-3

5.18

2.50

22.46

102.05

68.20

J-4

5.15

2.50

22.42

101.92

68.16


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Table 2 Ion components of the used formation water Component

Concentration, (mg/L)

Na+

14013

Ca2+

901.2

Mg2+

652.4

Cl-

26040.2


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Table 3 Interfacial tension between different surfactant solutions and oil phase Employed surfactant

IFT, mN/m

AEO

0.322

DTAB

0.075

GDTAB

0.056

GABEO

0.031


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Table 4 Related parameters of the used surfactants Surfactant

cmc, wt%

γcmc, mN/m

AEO

0.0058

33.6

DTAB

0.277

42.1

GDTAB

0.012

38.6

GABEO

0.004

32.5


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Energy & Fuels

Figures Fig. 1 Synthetic route of the cationic gemini surfactant GABEO SOCl2

Cl

N CH2CH2 N + + N CH2CH2 N

Polyether hydrophilic head group

Hydrophobic group/chain


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Fig. 2 Amott cell imbibition device

Rubber tube Oil drops

Core

Imbibition liquid


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Fig. 3 Infrared spectra of different products Intermediate product

Target product

1640 1364 3445

925 1115

2925 2860

4000

3500

3000

2500

2000

1500 -1

Wave number, cm


1000

500

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Fig. 4 NMR spectrum of the target product GABEO

3.63

1.226

3.52 3.23 4.0 3.73 3.39

4.0

3.5

0.826

2.24

3.0

2.5

1.506

2.0 


1.5

1.0

Page 31 of 38

Fig. 5 Effect of various surfactants on zeta potential at different concentrations 35 DTAB GDTAB GABEO AEO

30 25

Zeta potential, mV

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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20 15 10 5 0 -5 -10 0.00

0.05

0.10

0.15

Surfactant concentration, wt%


0.20

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Fig. 6 SEM images of various solid surfaces

(a) Oil-wet surface

(b) Surface treated with AEO

(c) Surface treated with DTAB

(d) Surface treated with GDTAB

(e) Surface treated with GABEO


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Fig. 7 Infrared spectra of different surfaces

1159

2849

3480

759

2917 1381

1691

4000

3500

3000

2500

2000

1500

1000

-1

Wavenumber, cm

(a) Oil-wet sandstone surface

1170

1275 760

3481

2851 2919

1616

1792

1692

4000

3500

3000

2500

2000

1500

-1

Wavenumber, cm

(b) Oil-wet sandstone surface treated by AEO


1000

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Fig. 8 Infrared spectra of different surfaces treated by various surfactants Treated by DTAB Treated by GDTAB Treated by GABEO

2850 2920

1378 1690

801 695 3425

4000

3500

1091

3000

2500

2000 -1

Wavenumber, cm


1500

1000

Page 35 of 38

Fig. 9 Effect of various surfactants on contact angles at different concentrations

140 AEO DTAB GDTAB GABEO

120

Contact angle, °

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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100

80

60

40 0.00

0.05

0.10

0.15

0.20

Surfactant concentration, wt%


0.25

0.30

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Page 36 of 38

Fig. 10 Mechanism of oil droplet curling by surfactant-induced wettability alteration σow

(Oil drop)

θw

σsw

(Water)

σso

θo

(Solid surface) Natural surface active substance (a)

(Water) σow

(Oil drop) Ion pair

θo σsw

θw

σso

(Solid surface) Surfactant (b)


Page 37 of 38

Fig. 11 Spontaneous imbibition curves of different surfactant systems 20 18 16 Recovery ratio, % OOIP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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14 12 10 8 AEO DTAB GDTAB GABEO

6 4 2 0 0

20

40

60

80

100

120

Time, hours


140

160

180

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Fig. 12 Mechanism for wettability alteration of oil-wet sandstone surface by GABEO

Low concentration

Gemini surfactant Carboxylic substance

(a)

Intermediate concentration

(b)

High concentration

(c)


Page 38 of 38

Mechanism of Wettability Alteration of an Oil-Wet Sandstone Surface

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