Novel Anionic-Nonionic Surfactant Based on Water-Solid Interfacial Wettability Control for Residual Oil Development

Irreversible colloidalasphaltene adsorption layers areformedon formation rock surfaces due to long-term contact with crude oil,and large amounts of crude oil adhere to these oil-wet layersto form residual oil films. This oil film is difficult to peel offdue to the strong oil-solid interface effect, which seriouslyrestricts further improvement in oil recovery. In this paper, thenovel anionic-nonionic surfactant sodium laurate ethanolamidesulfonate (HLDEA) exhibiting strong wetting control was synthesizedby introducing sulfonic acid groups into the nonionic surfactant lauratediethanolamide (LDEA) molecule through the Williamson etherificationreaction. The introduction of the sulfonic acid groups greatly improvedthe salt tolerance and the absolute value of the zeta potential ofthe sand particles. The experimental results showed that HLDEA alteredthe wettability of the rock surface from oleophilic to strongly hydrophilic,and the underwater contact angle increased substantially from 54.7to 155.9 degrees. In addition, compared with LDEA, HLDEA exhibited excellentsalt tolerance and enhanced oil recovery performance (the oil recoverywas improved by 19.24% at 2.6 x 10(4) mg/L salinity).Based on nanomechanical experimental results, HLDEA was efficientlyadsorbed on the core surfaces and regulated microwetting. Moreover,HLDEA effectively reduced the adhesion force between the alkane chainsand the core surface, which facilitated residual oil stripping andoil displacement. This new anionic-nonionic surfactant affordinggreat oil-solid interface wetting control has practical significancefor the efficient development of residual oil.