The development of a temperature- and salt-resistant
surfactant
system is of great significance in enhanced oil recovery. In this
study, two anionic–nonionic surfactants, alkylphenol polyoxyethylene
ether carboxylate sodium-10Na (APEC-10Na) and fatty alcohol polyoxyethylene
ether carboxylate sodium-9Na (AEC-9Na), were applied to construct
a compound surfactant system. When the total concentration was 0.3%
and the mass ratio of APEC-10Na to AEC-9Na was 7:3, the compound system
could reduce the interfacial tension between oil and water to 8.1
× 10–2 mN·m–1, which
could be attributed to the dense arrangement of the surfactant molecules
in the interface. The system can resist temperatures up to 110 °C
and tolerate a monovalent salt concentration of 18 × 104 mg L–1 and a divalent salt concentration of 8
× 103 mg L–1. The compound surfactant
system can modify the rock surface wettability from strong hydrophobicity
to strong hydrophilicity, with an underwater–oil contact angle
reaching 132.4° for the treated rock surface. The oil film peeling
rate of the compound system is 73.4%, which is 29.2% higher than that
of the commercial system and 41% higher than that of the formation
water. The oil recovery rate of the compound system in core displacement
experiments is 61.7%, which is 4.8% higher than that of the commercial
system and 14% higher than that of the formation water. The compound
surfactant system proposed in this work not only achieved low interfacial
tension under high-temperature and high-salinity conditions but also
realized effective interface wettability regulation, sufficient stripping
of adhered oil films, and promotion of oil droplet migration, providing
guidance in designing compound surfactant system for the efficient
development of high-temperature and high-salinity reservoirs.