Dialkyl Sulfobetaine Surfactants Derived from Guerbet Alcohol Polyoxypropylene–Polyoxyethylene Ethers for SP Flooding of High Temperature and High Salinity Reservoirs

Abstract

Dialkyl hydroxypropyl sulfobetaine (HSB) surfactants, C 16 GA-(PO) 5 -(EO) 3 -HSB and C 24 GA-(PO) 10 -(EO) 10 -HSB, were synthesized from Guerbet alcohols (GA) polyoxypropylene-polyoxyethylene (PO-EO) ethers and their behaviors in surfactant-polymer (SP) flooding of high temperature and high salinity reservoirs were examined and compared with their anionic hydroxypropyl sulfonate (HS) counterparts, C 16 GA-(PO) 5 -(EO) 3 -HS and C 24 GA-(PO) 10 -(EO) 10 -HS. The PO-EO chain embedded improves their aqueous solubility, and the sulfobetaines show better salt resistance than sulfonates. For a reservoir condition of total salinity 19,640 mg L −1 and 60-80 C, C 16 GA-(PO) 5 -(EO) 3 -HSB alone can reduce crude oil/connate water interfacial tension (IFT) to ultralow at 0.25-5 mM, which can be further widened to 0.1-5 mM by mixing with dodecylhexyl (C 12+6 ) glyceryl ether hydroxypropyl sulfobetaine (C 12+6 GE-HSB), a slightly hydrophobic surfactant. C 24 GA-(PO) 10 -(EO) 10 -HSB is more hydrophobic for the specified reservoir condition, however, by mixing with hexadecyl dimethyl hydroxypropyl sulfobetaine (C 16 HSB), a hydrophilic surfactant, ultralow IFT can also be achieved at a total concentration of 0.25-5 mM. The anionic counterparts can also reduce IFT to ultralow by mixing with C 12+6 GE-HSB and C 16 HSB, respectively. Moreover, the optimum binary mixture, C 16 GA-(PO) 5 -(EO) 3 -HSB/C 12+6 GE-HSB at a molar fraction ratio of 0.6/0.4, can keep the negatively charged solid surface water-wet (θ w = 12-23 ) in a wide concentration range, and can still achieve ultralow IFT after stored at 90 C for 90 days (initially 5 mM), which overall are favor of improving oil displacement efficiency at high temperature and high salinity reservoir conditions. Keywords Sulfobetaines Á Guerbet alcohols Á Alkyoxylated Á Ultralow interfacial tension Á Harsh reservoir conditions

Progress in research of sulfobetaine surfactants used in tertiary oil recovery

“…When a methyl group of the sulfobetaines is changed into a long‐chain hydrophobic group, the group becomes sulfobetaine surfactants (Figure 4). Sulfobetaine surfactants can be used in high‐temperature and high‐salinity reservoirs since its strong salt tolerance and heat resistance (Chen et al, 2021).…”

“…In addition, it was found that the way to improve the wettability alteration is to increase salinity and alkalinity (Kumar & Mandal, 2019). Sulfobetaine surfactants, as important zwitterionic surfactants, have become one of the TOR research priorities because of their stable performance, excellent resistance to high concentrations of acid, alkali, salt and high temperature, and good synergy with other surfactants, polymers and other chemical additives (Chen et al, 2021;Guo et al, 2014;Liu et al, 2021aLiu et al, , 2021b.…”