由于具有较高的驱油能力，CO_2驱逐步成为提高原油采收率研究的重点。但是注入中，CO_2极易沿高渗或裂缝窜流，在油藏中形成大量的滞留原油。窜流后，CO_2不能直接驱动原油，但是其与原油间仍存在质量传递，这种传质作用的强弱成为影响滞留原油采收率的关键。本项目针对油藏中的大量滞留原油，拟通过对CO_2进行化学改性的方法，构筑具有强CO_2-原油传质作用的改性CO_2驱油体系，提高滞留原油采收率。具体研究内容包括：（1）CO_2-原油传质作用对滞留原油采收率的影响规律研究；（2）强CO_2-原油传质作用的化学改性CO_2驱油体系构筑及改性机制探索；（3）改性CO_2体系驱油特征研究。通过研究，拟揭示CO_2-原油传质作用对滞留原油采收率的影响规律，得到具有强CO_2-原油传质作用的改性CO_2驱油体系，明确体系的驱油特征。研究结果可为低渗、特低渗非均质或裂缝性油藏，提高原油采率奠定技术基础。

Because of high ability to displace the crude oil, CO_2 flooding has become one of the most researched methods to enhance oil recovery. But in the injection process, CO_2 channels easily along the high permeability layers or the fracture, making a large mount of crude oil stranded in reservoirs. After the formation of CO_2 channeling, it can not drive the oil directly anymore, but the mass transfer between CO_2 and the crude oil still exists, and the strength of this mass transfer becomes the key factor affecting the recovery of the stranded oil. So, focusing on the stranded oil, the project plans to enhance the mass transfer between CO_2 and oil by adding chemical modifiers to CO_2 to improve recovery of this oil. The specific research content includes: (1) Research of the effects of mass transfer between CO_2 and oil on recovery of the stranded oil. (2) Construction of the oil displacing system with high ability of mass transfer between CO_2 and oil using the chemical modifiers and research of the modified mechanism. （3)Research of the oil displacement characteristics of the modified CO_2 system. By the research of this project, effects of mass transfer between CO_2 and oil on recovery of the stranded oil are supposed to be revealed. The system, having the high ability of mass transfer with crude oil, is hoped to be got. And its displacement characteristics would be figured out. Results of this project can establish the technical foundations for enhancing oil recovery of CO_2 flooding in the heterogeneous and fractured reservoirs, and especially for the low permeability heterogeneous reservoirs.