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ORIGINAL RESEARCH article

Front. Chem.
Sec. Molecular Liquids
Volume 12 - 2024 | doi: 10.3389/fchem.2024.1465706
This article is part of the Research Topic Advancements in Chemical Enhanced Oil Recovery: A Fundamental Chemistry Perspective View all articles

Construction of Middle-phase Microemulsion System and its Micromechanism on Displacing Residual Oil in Low-Permeability Porous Media

Provisionally accepted
Tianjiang WU Tianjiang WU 1Teng Wang Teng Wang 1*Yingxue Hu Yingxue Hu 2Jiajun Chen Jiajun Chen 1*Junwei Su Junwei Su 2*
  • 1 PetroChina Changqing Oilfield Company, Xi'an, China
  • 2 Xi'an Jiaotong University, Xi'an, China

The final, formatted version of the article will be published soon.

    The application of middle-phase microemulsions in enhancing oil recovery technology represents a significant area of research, particularly for improving production in low-permeability reservoirs. This study utilizes a mixed surfactant system composed of sodium dodecyl benzene sulfonate and coconut oil fatty acid lipopolyoxyethylene betaine at a mass ratio of 1:3, with n-butanol serving as the cosurfactant. The fish phase diagram was instrumental in determining the critical concentration range for alcohol (1.3%-3.7%) necessary for the formation of middle-phase microemulsions, along with a corresponding surfactant mass concentration of 0.3%-0.7%. Key salinity thresholds for middle-phase formation and disappearance were identified at 1.5% and 6.0%, respectively. Optimal solubilization effects were observed at approximately 4.8% NaCl mass concentration, which effectively reduced interfacial tension to 10−3 mN/m. Under specific kinetic conditions, in-situ formation of middle-phase microemulsions occurs as surfactants interact with crude oil within reservoir pores. In comparison to traditional water flooding, middle-phase microemulsions enhance viscosity and create an oil wall at the forefront of displacement. This mechanism facilitates the aggregation and movement of residual oil, which is crucial for enhancing crude oil recovery. Moreover, middle-phase microemulsions exhibit strong solubilization capabilities, making them particularly effective for mobilizing oil in blind-end and unswept areas. The ultra-low interfacial tension achieved between the microemulsion and crude oil promotes the elongation and fragmentation of pore-trapped oil into smaller droplets, ultimately aiding in their displacement and recovery via micro-pore outlets. This unique interaction underscores the potential of middle-phase microemulsion flooding to optimize oil recovery processes, especially in challenging reservoir environments such as those encountered in the Changqing Oilfield formations.

    Keywords: Middle-phase microemulsion, System construction, Solubilization capacity, micro-oil displacement mechanism, low-permeability reservoir

    Received: 16 Jul 2024; Accepted: 28 Oct 2024.

    Copyright: © 2024 WU, Wang, Hu, Chen and Su. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Teng Wang, PetroChina Changqing Oilfield Company, Xi'an, China
    Jiajun Chen, PetroChina Changqing Oilfield Company, Xi'an, China
    Junwei Su, Xi'an Jiaotong University, Xi'an, 710049, China

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.