An Experimental Investigation into the Role of an In Situ Microemulsion for Enhancing Oil Recovery in Tight Formations

Meiting Zeng, Chuanzhen Zang, Jie Li, Xiangyu Mou, Rui Wang, Haifu Li and Junjian Li ()
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Meiting Zeng: Engineering Technology Research Institute, Xinjiang Oilfield Company, No. 87, Shengli Road, Karamay 834000, China
Chuanzhen Zang: Engineering Technology Research Institute, Xinjiang Oilfield Company, No. 87, Shengli Road, Karamay 834000, China
Jie Li: Engineering Technology Research Institute, Xinjiang Oilfield Company, No. 87, Shengli Road, Karamay 834000, China
Xiangyu Mou: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), Beijing 102249, China
Rui Wang: Engineering Technology Research Institute, Xinjiang Oilfield Company, No. 87, Shengli Road, Karamay 834000, China
Haifu Li: Engineering Technology Research Institute, Xinjiang Oilfield Company, No. 87, Shengli Road, Karamay 834000, China
Junjian Li: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), Beijing 102249, China

Energies, 2024, vol. 17, issue 8, 1-16

Abstract: Surfactant huff-n-puff (HnP) has been shown to be an effective protocol to improve oil recovery in tight and ultratight reservoirs. The success of surfactant HnP for enhanced oil recovery (EOR) process depends on the efficiency of the designed chemical formula, as the formation of an in situ microemulsion by surfactant injection is considered to be the most desirable condition for achieving an ultra-low interfacial tension during the HnP process. In this work, we conducted experimental studies on the mechanism of in situ microemulsion EOR in the Mahu tight oil reservoir. Salinity scan experiments were carried out to compare different surfactants with crude oil from the Mahu reservoir, starting with the assessment of surfactant micellar solutions for their ability to form microemulsions with Mahu crude oil and examining the interfacial characteristics. Subsequently, detailed micromodels representing millimeter-scale fractures, micron-scale pores, and nano-scale channels were utilized to study the imbibition and flowback of various surfactant micellar solutions. Observations of the in situ microemulsion system revealed the mechanisms behind the enhanced oil recovery, which was the emulsification’s near-miscibility effect leading to microemulsion formation and its performance under low-interfacial-tension conditions. During the injection process, notable improvements in the micro-scale pore throat heterogeneity were observed, which improved the pore fluid mobility. The flowback phase improved the channeling between the different media, promoting a uniform movement of the oil–water interface and aiding in the recovery of a significant amount of the oil phase permeability.

Keywords: tight oil reservoirs; microemulsions; microfluidics; imbibition; enhanced oil recovery (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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