PERFORMANCE EVALUATION OF TETRABUTYLAMMONIUM BROMIDE-BASED DEEP EUTECTIC SOLVENTS IN ENHANCED OIL RECOVERY OF NIGERIAN HEAVY OIL

Abstract

Deep eutectic solvent (DES) is used as a green solvent in science due to its benefits over ionic liquids, such as biocompatibility and biodegradability, chemical stability with water, ease of preparation, and non-toxicity.DES 1 was successfully synthesized in a 1:2 molar ratio of Tetrabutylammonium bromide (TBAB) and polyethylene glycol 400 (PEG 400), while the novel DES 2 and DES 3 were synthesized in a 1:6 molar ratio of TBAB/ dimethyl sulfoxide (DMSO), and TBAB/N,N-dimethyl formamide (DMF) respectively. The performance(s) of the three DESs in the enhancement of heavy Nigerian crude oil recovery at ambient temperature was investigated. DES 1 recovered additional 16.07 % oil from core flooding using Berea sandstone core sample, resulting in an overall recovery of 53.44 %. DES 1 also resulted in an incremental recovery of 35.94 % from Niger-Delta sandstone, with a high ultimate recovery of 85.94 %. The presence of DES 2 and DES 3 were also shown to result in additional oil recovery. A drastic IFT reduction from 5.19 to 2.46mN/m was observed between the oil and the DES2 phase. Thus the study confirms that the presence of TBAB-based DES promotes reduction in the viscosity of the heavy oil and results in more oil recovery. Keywords: Deep eutectic solvents (DES), enhanced oil recovery, interfacial tension, tetrabutylammoniumbromide (TBAB)