Performances of Guerbet Alcohol Ethoxylates for Surfactant–Polymer Flooding Free of Alkali

Abstract

Two series of double-chain single-head nonionic surfactants, Guerbet alcohol ethoxylates (C m GA–E n ; m = 16 and 20, n = 5.7–24.0), were synthesized, and their performances as surfactants for surfactant–polymer (SP) flooding free of alkali were evaluated. The products have relatively low critical micelle concentrations [(6.8 × 10–7)–(1.0 × 10–5 mol/L)] and a wide range of surface tensions at the critical micelle concentration (γcmc) values (30.3–38.0 mN/m) at 25 °C, depending on both the alkyl-chain length and the number of ethylene oxide (EO) units. When used alone, these nonionic surfactants are not efficient for reducing crude oil/connate water interfacial tension (IFT), but their binary mixtures with a highly hydrophobic zwitterionic surfactant, didodecylmethyl hydroxylpropyl sulfobetaine (diC12HSB), are very efficient in reducing Daqing crude oil/connate water IFTs. Ultralow IFTs can be achieved in a wide total concentration range (0.3–10 mM) at 45 °C, and the low limit (0.3 mM) can be further reduced to 0.15 mM by adding an anionic surfactant, α-olefin sulfonate (AOS), to the binary mixtures at a small mole fraction (0.1). Both the binary and ternary mixtures display good resistance against adsorption by Daqing sandstone, and when dissolved in connate water, they prefer to keep the negatively charged rock surface water-wet and produce a crude-oil-in-water emulsion. In addition, the incorporation of AOS into the binary mixtures was found to be beneficial for preventing crystallization of zwitterionic surfactant and flocculation of nonionic surfactants, as reported previously. Comparatively, for SP flooding free of alkali, the Guerbet alcohol ethoxylates are as excellent as the glyceryl ether ethoxylates, nonionic surfactants with a similar double-alkyl single-head structure, but are far superior to the conventional nonionic surfactants with monoalkyl single-head structures.

A New Series of Double‐Chain Single‐Head Sulfobetaine Surfactants Derived from 1,3‐Dialkyl Glyceryl Ether for Reducing Crude Oil/Water Interfacial Tension

“…The operation was repeated until ultralow IFT can no longer be achieved. The total adsorption time is taken as a measure of the resistance against adsorption by the sandstone (Yan et al, , , ). The connate water has a pH of 9.1 in which the sandstones are negatively charged and no extra alkali or acid was added into the dispersion (Cui et al, , ).…”

A novel binary flooding system of a biobased surfactant and hydrophobically associating polymer with ultralow interfacial tensions

“…Yan et al 2 reported that a nonionic/zwitterionic formulation with polyacrylamide achieved four times the ultralow IFT (ESI Table 11 †). Fig.…”

“…[1][2][3][4] However, the alkali in the ASP system simultaneously resulted in the reduction of reservoir permeability due to the dispersion and migration of clay and the alkaline scaling in formation. 5 Alkalifree binary surfactant-polymer (SP) ooding with ultralow interfacial tension (#10 À3 mN m À1 ) is a promising approach among tertiary oil recovery methods.…”

“…In the absence of alkali, however, the most traditional surfactant-polymer ooding systems could not reach the required ultralow interfacial tension, and may consequently fail in EOR. 2,9,10 In the present work, we developed an alkali free binary ooding system consisting of the biobased zwitterionic surfactant and hydrophobically associating polymer with ultralow interfacial tension. Zwitterionic surfactants usually have lower critical micelle concentration (CMC), 11 better water solubility 12 and satised interfacial tensions.…”

“…2 For the binary system, ultralow IFT was achieved aer two cycles (Table 3). At this time, the viscosity retention rate of the binary system was 93% (ESI Table 5 †).…”