Oil production characteristics and CO_(2)storage mechanisms of CO_(2)flooding in ultra-low permeability sandstone oil reservoirs  

作　　者：LIU Xiliang CHEN Hao LI Yang ZHU Yangwen LIAO Haiying ZHAO Qingmin ZHOU Xianmin ZENG Hongbo 

机构地区：[1]Hainan Institute of China University of Petroleum(Beijing),Beijing 102249,China [2]State Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China [3]Donadeo Innovation Centre for Engineering,University of Alberta,Edmonton T6G1H9 Canada [4]China Petroleum&Chemical Corporation,Beijing 100728,China [5]Sinopec Petroleum Exploration and Production Research Institute,Beijing 102206,China [6]Acrocean Sci&Tech Development LLC,Houston 77433,United States

出　　处：《Petroleum Exploration and Development》2025年第1期196-207,共12页石油勘探与开发(英文版)

基　　金：Supported by the National Natural Science Foundation of China(52274053);Natural Science Foundation of Beijing(3232028).

摘　　要：Using the ultra-low permeability reservoirs in the L block of the Jiangsu oilfield as an example,a series of experiments,including slim tube displacement experiments of CO_(2)-oil system,injection capacity experiments,and high-temperature,high-pressure online nuclear magnetic resonance(NMR)displacement experiments,are conducted to reveal the oil/gas mass transfer pattern and oil production mechanisms during CO_(2) flooding in ultra-low permeability reservoirs.The impacts of CO_(2) storage pore range and miscibility on oil production and CO_(2) storage characteristics during CO_(2) flooding are clarified.The CO_(2) flooding process is divided into three stages:oil displacement stage by CO_(2),CO_(2) breakthrough stage,CO_(2) extraction stage.Crude oil expansion and viscosity reduction are the main mechanisms for improving recovery in the CO_(2) displacement stage.After CO_(2) breakthrough,the extraction of light components from the crude oil further enhances oil recovery.During CO_(2) flooding,the contribution of crude oil in large pores to the enhanced recovery exceeds 46%,while crude oil in medium pores serves as a reserve for incremental recovery.After CO_(2) breakthrough,a small portion of the crude oil is extracted and carried into nano-scale pores by CO_(2),becoming residual oil that is hard to recover.As the miscibility increases,the CO_(2) front moves more stably and sweeps a larger area,leading to increased CO_(2) storage range and volume.The CO_(2) full-storage stage contributes the most to the overall CO_(2) storage volume.In the CO_(2) escape stage,the storage mechanism involves partial in-situ storage of crude oil within the initial pore range and the CO_(2) carrying crude oil into smaller pores to increase the volume of stored CO_(2).In the CO_(2) leakage stage,as crude oil is produced,a significant amount of CO_(2) leaks out,causing a sharp decline in the storage efficiency.

关 键 词：ultra-low permeability reservoir CO_(2)flooding MISCIBILITY oil production characteristics storage characteristics 

分 类 号：F42[经济管理—产业经济]