A New Type of Sulfobetaine Surfactant with Double Alkyl Polyoxyethylene Ether Chains for Enhanced Oil Recovery

Synthesis, characterization and performance of lignin carboxyl betaine zwitterionic surfactants for application in enhanced oil recovery

The objective of this study was to synthesize lignin carboxyl betaine zwitterionic surfactants (LCBS) from alkali lignin through a three-step reaction involving epoxidation, amination, and quaternization. The synthesized LCBS were characterized using infrared spectroscopy (IR) and thermogravimetric (TG) analysis. To assess their potential for enhanced oil recovery (EOR), the physicochemical properties of the LCBS surfactants, such as surface tension, emulsification, temperature resistance, salt resistance, and interfacial properties, were evaluated using standard experimental methods for surfactants applied in oil displacement. The LCBS surfactants exhibited higher surface activity, with low surface tension values ranging from 29.65 mN m^-1 to 31.85 mN m^-1 at the corresponding critical micelle concentration (cmc), also the significant emulsifying performance of LCBS surfactants was proved in the emulsifying experiments. Moreover, the synthesized LCBS surfactants were found to be suitable for use in harsh reservoirs of high-salinity and high-temperature, as confirmed by the temperature and salt resistance measurements. The interfacial tension (IFT) tests between Huabei crude oil and LCBS surfactants suggested that these surfactants could effectively extract the crude oil containing heavy components such as colloid and asphaltene, and ultra-low IFT values could be achieved with the addition of weak alkali.

Challenges and future of chemical assisted heavy oil recovery processes

The primary method for heavy oil and bitumen production across the world is still in-situ steam-based technology. There are some drawbacks associated with steam-driven heavy oil recovery methods such as cyclic steam stimulation (CSS), steam flooding, and steam-assisted gravity drainage (SAGD). These cons include the high greenhouse gas footprint, low heavy oil/bitumen recovery, and difficulty in stop operation in emergency conditions. There exists a need for an improved method for recovering residual oils after applying steam injection. One of the potential technologies for doing this is chemical assisted heavy oil recovery, especially alkaline and surfactant additives. But the challenging question is how to develop a chemical-based oil recovery method considering long-term steam-rock interactions. Several associated issues of chemical additives, including adsorption behavior of surfactant at reservoir conditions and thermal stability of surfactant at steam chamber temperature, make this question more complex. This paper addresses all these concerns and provides solid knowledge regarding this technology. We delve into newly formulated chemicals for coupling with thermal oil recovery techniques that are still limited to lab-scale research, with the need for further studies. This critical review also provides the opportunities and challenges associated with chemical assisted heavy oil/bitumen production in a post-steam injection scenario. Finally, different aspects of such a method are covered in this review, along with practical information on field trials and best practices across the world.

Role of Ionic Headgroups on the Thermal, Rheological, and Foaming Properties of Novel Betaine-Based Polyoxyethylene Zwitterionic Surfactants for Enhanced Oil Recovery

Long-term thermal stability of surfactants under harsh reservoir conditions is one of the main challenges for surfactant injection. Most of the commercially available surfactants thermally degrade or precipitate when exposed to high-temperature and high-salinity conditions. In this work, we designed and synthesized three novel betaine-based polyoxyethylene zwitterionic surfactants containing different head groups (carboxybetaine, sulfobetaine, and hydroxysulfobetaine) and bearing an unsaturated tail. The impact of the surfactant head group on the long-term thermal stability, foam stability, and surfactant–polymer interactions were examined. The thermal stability of the surfactants was assessed by monitoring the structural changes when exposed at high temperature (90 °C) for three months using 1H-NMR, 13C-NMR, and FTIR analysis. All surfactants were found thermally stable regardless of the headgroup and no structural changes were evidenced. The surfactant–polymer interactions were dominant in deionized water. However, in seawater, the surfactant addition had no effect on the rheological properties. Similarly, changing the headgroup of polyoxyethylene zwitterionic surfactants had no major effect on the foamability and foam stability. The findings of the present study reveal that the betaine-based polyoxyethylene zwitterionic surfactant can be a good choice for enhanced oil recovery application and the nature of the headgroup has no major impact on the thermal, rheological, and foaming properties of the surfactant in typical harsh reservoir conditions (high salinity, high temperature).