In Situ Emulsification Synergistic Self-Profile Control System on Offshore Oilfield: Key Influencing Factors and EOR Mechanism

Liangliang Wang (), Minghua Shi, Jiaxin Li (), Baiqiang Shi, Xiaoming Su, Yande Zhao, Qing Guo and Yuan Yuan
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Liangliang Wang: Bailie School of Petroleum Engineering, Lanzhou City University, Lanzhou 730070, China
Minghua Shi: School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China
Jiaxin Li: Yanchang Oilfield Co., Ltd., Yan’an 716000, China
Baiqiang Shi: Technical Center, No. 1 Oil Production Plant, PetroChina Qinghai Oilfield Company, Mangya 816400, China
Xiaoming Su: Bailie School of Petroleum Engineering, Lanzhou City University, Lanzhou 730070, China
Yande Zhao: Bailie School of Petroleum Engineering, Lanzhou City University, Lanzhou 730070, China
Qing Guo: Bailie School of Petroleum Engineering, Lanzhou City University, Lanzhou 730070, China
Yuan Yuan: Bailie School of Petroleum Engineering, Lanzhou City University, Lanzhou 730070, China

Energies, 2025, vol. 18, issue 14, 1-18

Abstract: The in situ emulsification synergistic self-profile control system has wide application prospects for efficient development on offshore oil reservoirs. During water flooding in Bohai heavy oil reservoirs, random emulsification occurs with superimposed Jamin effects. Effectively utilizing this phenomenon can enhance the efficient development of offshore oilfields. This study addresses the challenges hindering water flooding development in offshore oilfields by investigating the emulsification mechanism and key influencing factors based on oil–water emulsion characteristics, thereby proposing a novel in situ emulsification flooding method. Based on a fundamental analysis of oil–water properties, key factors affecting emulsion stability were examined. Core flooding experiments clarified the impact of spontaneous oil–water emulsification on water flooding recovery. Two-dimensional T1–T2 NMR spectroscopy was employed to detect pure fluid components, innovating the method for distinguishing oil–water distribution during flooding and revealing the characteristics of in situ emulsification interactions. The results indicate that emulsions formed between crude oil and formation water under varying rheometer rotational speeds (500–2500 r/min), water cuts (30–80%), and emulsification temperatures (40–85 °C) are all water-in-oil (W/O) type. Emulsion viscosity exhibits a positive correlation with shear rate, with droplet sizes primarily ranging between 2 and 7 μm and a viscosity amplification factor up to 25.8. Emulsion stability deteriorates with increasing water cut and temperature. Prolonged shearing initially increases viscosity until stabilization. In low-permeability cores, spontaneous oil–water emulsification occurs, yielding a recovery factor of only 30%. For medium- and high-permeability cores (water cuts of 80% and 50%, respectively), recovery factors increased by 9.7% and 12%. The in situ generation of micron-scale emulsions in porous media achieved a recovery factor of approximately 50%, demonstrating significantly enhanced oil recovery (EOR) potential. During emulsification flooding, the system emulsifies oil at pore walls, intensifying water–wall interactions and stripping wall-adhered oil, leading to increased T2 signal intensity and reduced relaxation time. Oil–wall interactions and collision frequencies are lower than those of water, which appears in high-relaxation regions (T1/T2 > 5). The two-dimensional NMR spectrum clearly distinguishes oil and water distributions.

Keywords: offshore oil reservoir; heavy crude oil; in situ emulsification; profile control; EOR mechanism (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: 2025
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