Abstract: CO₂ EOR and storage is an effective method to reduce greenhouse gas emission associated with tertiary oil recovery. With the CO₂ breakthrough in production wells, selection the best way to dispose the associated gas will become important. In this paper, the general rule of CO₂-associated gas produced during CO₂ injection is analyzed. The feasibility and application range of three production gas disposal options are evaluated, including direct re-injection or mixed with pure CO₂ for re-injection, combustion for power generation associated with flue gas re-injection, and CO₂ capture for rejection. The preliminary screen criteria for these gas disposal options is established. Further, four different CO₂ capture techniques are also compared in applicability and economy, including chemical absorption, low-temperature fractionation, pressure swing adsorption and membrane separation. Taking CO₂ EOR and storage projects in Weyburn and Jilin oilfields, the main process of CO₂recycling is analyzed, which can provides valuable insights for the CO₂disposal in the other CO₂ EOR and storage projects. The results show that direct re-injection or mixed with pure CO₂ for re-injection is preferred for the treatment of CO₂-associated gas in the oil field. Secondly, CO₂separation and purification of the produced gas is considered. The scale of CO₂-EOR plants are usually small or middle in domestic, which choose pressure swing adsorption and low-temperature fractionation, while the large scale plants in foreign countries once used chemical absorption and membrane separation to capture CO₂ from associated gas.

Key words: CO₂ flooding, capture and separation, scheme selection, case analysis

摘要： CO₂驱及地质埋存技术是油田提高采收率和减少温室气体排放的有效手段，但随着CO₂在油井中突破，面临着含CO₂伴生气的处置技术和捕集回注工艺的优选问题。本文分析了油田CO₂驱产出气一般规律，论证了含CO₂伴生气直接/掺和回注、燃气轮机/锅炉燃烧及烟道气回注和捕集分离回注等处置方案的可行性及适用范围，初步建立了含CO₂伴生气处置方案优选依据。重点比较了化学吸收法、低温分馏法、变压吸附法和膜分离等CO₂捕集分离工艺的适用性和经济性。基于Weyburn油田和吉林油田CO₂驱项目，分析了油田CO₂驱产出气处置及回注工艺的主要流程。研究结果表明：对于油田含CO₂伴生气的处置，首选直接/掺和回注；其次考虑对产出气进行CO₂分离提纯，国内CO₂驱项目一般小到中等规模，变压吸附和低温分馏工艺受到青睐，国外大规模CO₂驱项目则有采用膜分离和化学吸收法捕集分离CO₂的经验。

关键词: 二氧化碳驱, 二氧化碳捕集, 方案选择, 案例分析