Investigations on the enhanced oil recovery capacity of novel bio-based polymeric surfactants

Abstract

Chemical enhanced oil recovery (cEOR) remains one of the most potent tertiary recovery methods. However, because of the complexity, cost, and environmental risks, attention is shifting towards bio-based polymeric surfactants as a possible alternative. Due to its vast abundance, cellulose has been identified as a source and cheap means of developing bio-based chemicals for oil recovery. In this study, novel hydrophobically modified cellulose sulphates, DPEA-Cell-OSO3−I (D-I) and DPEA-Cell-OSO3−II (D-II), were synthesized via microwave-assisted REDOX-mediated free-radical random copolymerization. Molecular characterization using nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) revealed their unique molecular features. In particular, D-II is identified as a mesoporous material. Rheological studies carried out on an economic concentration range of 50 to 1500 ppm showed that the novel products have moderate thickening properties, with viscosities less than 100 cP. Furthermore, it was discovered that the fluids are thermo-viscosifying and dilatant as well. Interfacial tension investigations revealed that they are surface-active with interfacial tension (IFT) lowering profiles improving with temperature as well, dropping down to the levels of 0.01 mN/m for D-I. They also demonstrated strong emulsifying capacity as Windsor types –II, +II, and middle phase microemulsion type III were produced during spontaneous emulsification tests. During coreflooding, D-I and D-II attained recoveries of 36 % and 53 %, respectively, over waterflood. D-II in particular had a very high residual resistant factor of 80, which is attributed to its dilatant nature, and emulsifying capabilities. In all, the properties and performances of the novel cellulose sulphate derivatives were linked to their molecular structures and architectures. Most importantly, these bio-based EOR materials will be suitable for high-temperature reservoirs.