Higher Fatty Acid-Based CO2-Controllable Dual-Circulation Approach for Oil Recovery

In this article, a higher fatty acid-based ternary CO2-controllable dual-circulation had been successfully constructed, where it provided an excellent oil recovery performance and all solvents could be cycled. This dual-circulation adopted the oil-soluble higher fatty acid (HFA) as the outside loop to extract oil and selected poly(propylene glycol) bis(2-aminopropylether) (Jeffamine D230) as the inner loop to impel the outside loop. In washing oil technology, D230 and HFA as cleaning solvents are ideal substitutes for traditional tertiary amines. First, there is the electrostatic interaction between HFA (represented by n-decanoic acid) and D230, as detected by 1H MNR. The circulation of the system is supported by the rapid CO2-switchable behaviors of HFA-D230, where the reversible phenomenon was recorded by a pH meter and a conductivity meter. In addition, the HFA/D230/water system has demonstrated the cyclic process of dissolving the oil in the simulated oil (the dodecane, kerosene, and diesel) recovery experiment. Finally, the n-decanoic acid (C10-HFA)/D230/water ternary dual-circulation system was obtained as the optimal scheme due to its excellent recovery and separation property. During the separation of simulated oil by using the C10-HFA/D230/water system, the recovery rate of the simulated oil was more than 93% and there was no residual n-decanoic acid by GC/MS analysis. This dual-circulation was successfully established, providing a new method to replace the traditional tertiary amine for oil recovery.