Enhancing oil recovery of sandstone core samples using an innovative surfactant blend fighting severe reservoir conditions

Abstract Surfactants are a vital component of enhanced oil recovery, offering the potential to significantly increase oil production from mature and challenging reservoirs. This study examined the use of nonylphenol ethoxylate (NPE) and its modified version, which is blended with 2-butoxyethanol (butyl glycol), for enhancing oil recovery (EOR). Results showed that butyl glycol enhances NPE’s efficiency and stability under challenging reservoir conditions. Where the blend significantly reduced the interfacial tension (8.5 mN/m vs. 12 mN/m for NPE alone). Using two sandstone reservoir rock slices, the contact angle for the blend was lower (27.7° & 30.5°) than that of the surfactant alone (42° & 39.6°) for both tested samples. This means the rock wettability is modified into stronger water-wet characteristics. Tertiary flooding of sandstone core samples confirmed these improvements, yielding (38.1 % S or ), compared to (30 % S or ) with NPE alone. This study demonstrates the potential of this novel, cost-effective surfactant blend to effectively extract more oil under challenging reservoir conditions.