Abstract: Steam quality is a critical factor influencing the effectiveness and economic efficiency of steam injection for enhanced oil recovery. In the later stage of conventional steam injection, the oil steam ratio is low, and different kinds of gas such as carbon dioxide and flue gas are often employed to reduce steam consumption. However, the unclear mechanism by which non-condensable gas admixture affects steam quality remains a significant limitation in the advancement of gas-assisted steam injection technologies. This study utilizes a high-temperature, high-pressure visual PVT experimental system to set up two experiments including constant-volume cooling and constant-temperature volume reduction. The experiment was conducted under conditions of steam temperatures ranging from 90 ℃ to 150 ℃ and pressures between 0 MPa and 0.451 MPa. It probes into the effect of blending varying proportions of four non-condensable gases, i.e., carbon dioxide, methane, ethane, and ammonia, on steam quality. The findings reveal that the gas admixture such as carbon dioxide and ammonia enhances steam quality, with ammonia exhibiting a more significant effect than carbon dioxide. In contrast, the admixture of gases like methane and ethane decreases steam quality, with methane showing a stronger reduction effect than ethane. This research elucidates the fundamental principles governing the impact of mixing four non-condensable gases on steam quality, providing valuable guidance for the selection of gas types in the gas-assisted steam thermal recovery of heavy oil.

Key words: heavy oil, steam quality, non-condensable gas, methane, carbon dioxide

摘要： 蒸汽干度是影响注汽热采开发效果和经济性的关键因素之一,常规注蒸汽开发后期油汽比低,为减少蒸汽用量常采用二氧化碳、烟道气等辅助开发。但非凝结气体的掺混对注入过程蒸汽干度的影响机理不清是制约气体辅助蒸汽开发技术的重要问题。通过高温高压可视化PVT实验系统,在蒸汽温度为90~150 ℃、压力为0~0.451 MPa的工况下,设置定容降温与定温降容两组实验,深入探讨了掺混不同比例的二氧化碳、甲烷、乙烷、氨气4种非凝结气体对蒸汽干度的影响。研究结果表明,二氧化碳、氨气等气体掺混可提高蒸汽干度,且氨气的提高效果强于二氧化碳,而甲烷、乙烷等气体掺混会降低蒸汽干度,且甲烷的降低效果强于乙烷。揭示了4种非凝结气体掺混对蒸汽干度影响的基础规律,可为气体辅助蒸汽热采稠油的气体种类选择提供借鉴与参考。

关键词: 稠油, 蒸汽干度, 非凝结气体, 甲烷, 二氧化碳