石油钻采工艺2025，Vol.47Issue(5)：569-578,10.DOI:10.13639/j.odpt.202508010
在线核磁原位动态表征水驱转CO2驱剩余油动用机制
In-situ dynamic characterization of residual oil displacement mechanism by CO2 after water flooding using online nuclear magnetic resonance
摘要
Abstract
To enhance the oil recovery in the middle-deep reservoirs of the Jidong Oilfield,this study investigates the controlling mechanism of pore-throat structure on oil displacement efficiency during water flooding and miscible CO2 flooding,providing a theoretical basis for optimizing development strategies.By integrating online NMR displacement and high-pressure mercury injection experiments,a conversion relationship between NMR T2 spectra and mercury injection data was established.This allowed for the quantitative characterization of pore-throat structure using average pore-throat radius and sorting coefficient.Systematic water flooding and miscible CO2 flooding experiments were conducted on core samples with high,medium,and low permeability.The results indicate that pore-throat structure parameters decrease with decreasing permeability.During water flooding,high-and medium-permeability cores primarily utilized micropores(utilization rates of 60.02%～80.11%),while low-permeability cores showed extensive utilization of sub-micropores and micropores(44.63%～94.68%),with nanopores contributing 18.52%.A strong positive correlation was observed between water flooding efficiency and both permeability(coefficient of determination,R2＞0.75)and average pore-throat radius(R2=0.85).In the miscible CO2 flooding stage,the utilization rates across the full pore-throat size range in medium-and low-permeability cores(17.09%～31.49%)were significantly higher than those in high-permeability cores(14.57%～16.63%).The incremental oil recovery from CO2 flooding showed a strong negative correlation with permeability,average pore-throat radius,and sorting coefficient(R2≥0.80).This study demonstrates that pore-throat structure is a key factor controlling oil displacement efficiency.It is recommended to prioritize the development of medium and high-permeability zones during water flooding and focusing on exploiting the potential of low-permeability zones during subsequent miscible CO2 flooding.The research findings provide a scientific basis for enhancing oil recovery in the Jidong Oilfield and similar reservoirs.关键词
在线核磁/驱替实验/孔隙结构/水驱/CO2驱/驱油效率/开发对策Key words
online NMR/displacement experiments/pore structure/water flooding/CO2 flooding/displacement efficiency/development strategies分类
石油、天然气工程引用本文复制引用
赵耀,于忠良,党雪维,沈贵红,卢家亭..在线核磁原位动态表征水驱转CO2驱剩余油动用机制[J].石油钻采工艺,2025,47(5):569-578,10.基金项目
中国石油天然气股份有限公司科技项目"低渗/致密油藏大幅提高采收率关键技术研究"(编号:2023ZZ17YJ03). （编号:2023ZZ17YJ03）
