Profile improvement during CO2 flooding n ultra-low permeability reservoirs

• Published in: 石油科学：英文版 no. 2; pp. 279 - 286
• Main Author: Zhao Fenglan Zhang Lei Hou Jirui Cao Shujun
• Format: Journal Article
• Language: English
• Published: 2014
• Subjects: CO2驱; 个人资料; 乙二胺; 二氧化碳; 低渗透油藏; 反应机理; 地层非均质性; 高流动性
• ISSN: 1672-5107

Gas flooding such as CO2 flooding may be effectively applied to ultra-low permeability reservoirs, but gas channeling is inevitable due to low viscosity and high mobility of gas and formation heterogeneity. In order to mitigate or prevent gas channeling, ethylenediamine is chosen for permeability profile control. The reaction mechanism of ethylenediamine with CO2, injection performance, swept volume, and enhanced oil recovery were systematically evaluated. The reaction product of ethylenediamine and CO2 was a white solid or a light yellow viscous liquid, which would mitigate or prevent gas channeling. Also, ethylenediamine could be easily injected into ultra-low permeability cores at high temperature with protective ethanol slugs. The core was swept by injection of 0.3 PV ethylenediamine. Oil displacement tests performed on heterogeneous models with closed fractures, oil recovery was significantly enhanced with injection of ethylenediamine. Experimental results showed that using ethylenediamine to plug high permeability layers would provide a new research idea for the gas injection in fractured, heterogeneous and ultra-low permeability reservoirs. This technology has the potential to be widely applied in oilfields.