Determination of equivalent alkane carbon number for West Siberian oils as a stage of optimisation in surfactant-polymer compositions for chemical flooding

The hydrophobicity of oil and oil products can be characterised in terms of its equivalent alkane carbon number (EACN). This characteristic can be determined on the basis of the correlation between the interfacial tension data and other characteristics for homologous oils and a number of alkanes having subsequent interpretation for oil and oil products. The EACN is a useful metric for selecting an effective surfactant for the emulsification of oil and oil products. The research is aimed at determining the equivalent alkane car-bon number of various crude oil samples obtained in the oil fields of Western Siberia using standard high-performance compositions of imported and domestic industrial sulphonate surfactants. In order to determine the EACN of oil and oil products, the S* characteristic was applied representing the optimal NaCl concentration (optimum salinity) in the aqueous surfactant phase, as well as providing the minimum surface tension and formation of the maximum microemulsion volume during the phase experiment at the interface with the hydro-carbon phase. Direct determination of the interfacial tension at the "oil / surfactant solution" interface was car-ried out with a tensiometer using the spinning drop method at a temperature of 87 °С. Linear dependencies are identified in accordance to the empirical correlation equations between the EACN, surfactant parameters and phase behaviour parameters of aqueous surfactant solutions and oil or a mixture of hydrocarbons. The K characteristic parameter of the proposed three standard surfactant compositions is determined to be consistent with the literature data for individual surfactants. The composition of industrial surfactants for determining the EACN of oil and oil products is proposed. The equations of linear regression for the logS* ~ EACN dependency with high correlation coefficients (R² = 0.9444-0.9999) are obtained, resulting in the determination of the EACN for kerosene and seven oil samples from Western Siberian oil fields. Promising surfactants can be selected on the basis of this indicator for reducing interfacial tension in the "hydrocarbon / water solution" system, as well as for predicting the most effective composition for obtaining emulsions.

1. Creton B, Lévêque I, Oukhemanou F. Equivalent alkane carbon number of crude oils: A predictive model based on machine learning. Oil and Gas Science and Technology – Rev. IFP Energies nouvelles. 2019;74(30). 11 p. https://doi.org/10.2516/ogst/2019002

2. Chang L, Pope GA, Jang SH, Tagavifar M. Prediction of microemulsion phase behavior from surfactant and cosolvent structures. Fuel. 2019; 237:494–514. https://doi.org/10.1016/j.fuel.2018.09.151

3. Lu J, Liyanage PJ, Solairaj S, Adkins S, Arachchilage GP, Kim DH, et al. New surfactant developments for chemical enhanced oil recovery. Journal of Petroleum Science and Engineering. 2014;120:94–101. https://doi.org/10.1016/j.petrol.2014.05.021

4. Wang S, Chen C, Yuan N, Ma Y, Ogbonnaya OI, Shiau B, et al. Design of extended surfactant-only EOR formulations for an ultrahigh salinity oil field by using hydrophilic lipophilic deviation (HLD) approach: From laboratory screening to simulation. Fuel. 2019;254:115698. https://doi.org/10.1016/j.fuel.2019.115698

5. Zarate-Muñoz S, Troncoso AB, Acosta E. The cloud point of alkyl ethoxylates and its predicttion with the hydrophilic-lipophilic difference (HLD) framework. Langmuir. 2015;31(44):12000–12008. https://doi.org/10.1021/acs.langmuir.5b03064

6. Arpornpong N, Charoensaeng A, Khaodhiar S, Sabatini DA. Formulation of microemulsion-based washing agent for oil recovery from spent bleaching earth-hydrophilic lipophilic deviation conceptю Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2018;541:87–96. https://doi.org/10.1016/j.colsurfa.2018.01.026

7. Zhu Y-W, Zhao R-H, Jin Z-Q, Zhang L, Zhang L, Luo L, Zhao S. Influence of crude oil fractions on interfacial tensions of alkylbenzene sulfonate solutions. Energy and Fuels. 2013;27(8):4648–4653. https://doi.org/10.1021/ef4009357

8. Li S, Willoughby JA, Rojas OJ. Oil-in-water emulsions stabilized by carboxymethylated lignins: Properties and energy prospects. ChemSusChem. 2016;9(17):2460–2469. https://doi.org/10.1002/cssc.201600704

9. Liu H, Zhou P, Wu Z, Chen S, Ding C. Solubilization behavior of organic mixtures in optimum Winsor type III microemulsion systems of sodiumdodecyl sulfate. Journal of Surfactants and Detergents. 2018;21(4):497–507. https://doi.org/10.1002/jsde.12053

10. Salager J-L, Morgan JC, Schechter RS, Wade WH, Vasquez E. Optimum formulation of surfactant/water/oil systems for minimum interfacial tension or phase behavior. Society of Petroleum Engineers Journal. 1979;19(2):107–115. https://doi.org/10.2118/7054-PA

11. Acosta E, Mai PD, Harwell JH, Sabatini DA. Linker-modified microemulsions for a variety of oils and surfactants. Journal of Surfactants and Detergents. 2003;6(4):353–363. https://doi.org/10.1007/s11743-003-0281-2

12. Acosta EJ, Yuan JS, Bhakta AS. The characteristic curvature of ionic surfactants. Journal of Surfactants and Detergents. 2008;11(2):145–158. https://doi.org/10.1007/s11743-008-1065-7

13. Anton RE, Andérez JM, Bracho C, Vejar F, Salager J-L. Practical surfactant mixing rules based on the attainment of microemulsion-oil-water three-phase behavior systems. Advances in Polymer Science. 2008;218(1):83–113. https://doi.org/10.1007/12_2008_163

14. Acosta EJ, Bhakta AS. The HLD‐NAC mod-el for mixtures of ionic and nonionic surfactants. Journal of Surfactants and Detergents. 2009;12(1):7– 19. https://doi.org/10.1007/s11743-008-1092-4

15. Wan W, Zhao J, Harwell JH, Shiau B-J. Characterization of crude oil equivalent alkane carbon number (EACN) for surfactant flooding design. Journal of Dispersion Science and Technology. 2016;37(2):280–287. https://doi.org/10.1080/01932691.2014.950739

16. Solairaj S, Britton C, Lu J, Kim DH, Weerasooriya U, Pope GA. New correlation to predict the optimum surfactant structure for EOR. In: SPE – DOE Improved Oil Recovery Symposium Proceedings. 2012, vol. 2, p. 1390–1399.

17. Karpan VM, Volokitin YI, Shuster MY, Tigchelaar W, Chmuzh IV, Koltsov IN, et al. West salym ASP pilot: Project front-end engineering. In: SPE – DOE Improved Oil Recovery Symposium Proceedings. 2014, vol. 3, p. 1725–1734.

18. Koltsov I, Groman A, Milchakov S, Tretyakov N, Panicheva L, Volkova S, et al. Evaluating reservoir fluids geochemistry for planning of surfactant-polymer flooding. In: IOR 2019 – 20th European Symposium on Improved Oil Recovery. Conference Proceedings, April 2019, Pau, France, 2019, vol. 2019, p. 1–17. https://doi.org/10.3997/2214-4609.201900091

19. Wu B, Shiau B, Sabatini DA, Harwell JH, Vu DQ. Formulating microemulsion systems for a weathered jet fuel waste using surfactant/ cosurfactant mixtures. Separation Science and Technology. 2000;35(12):1917–1937. https://doi.org/10.1081/SS-100100627

20. Witthayapanyanon A, Harwell JH, Sabatini DA. Hydrophilic-lipophilic deviation (HLD) method for characterizing conventionl and extended surfactants. Journal of Colloid and Interface Science. 2008:325(1):259–266. https://doi.org/10.1016/j.jcis.2008.05.061

21. Do LD, Witthayyapayanon A, Harwell JH, Sabatini DA. Environmentally friendly vegetable oil microemulsions using extended surfactants and linkers. Journal of Surfactants and Detergents. 2009;12(2):91–99. https://doi.org/10.1007/s11743-008-1096-0

22. Witthayapanyanon A, Acosta EJ, Har-well JH, Sabatini DA. Formulation of ultralow interfacial tension systems using extended surfactants. Journal of Surfactants and Detergents. 2006; 9(4):331–339. https://doi.org/10.1007/s11743-006-5011-2

23. Phan TT, Harwell JH, Sabatini DA. Effects of triglyceride molecular structure on optimum formulation of surfactant-oil-water systems. Journal of Surfactants and Detergents. 2010;13(2):189–194. https://doi.org/10.1007/s11743-009-1155-1