Abstract: Aiming at the difficult flow-back of fracturing fluid in low-permeability and low-pressure gas reservoir,a new type of carbon dioxide foam fracturing technology is proposed.The effects of temperature field change in well-bore and reservoir during fracturing on the gasliquid transferring were investigated. The laboratory experiments for improving the rheology of carbon dioxide foam fracturing fluid and treatment effectiveness of constant-internal-phase technology were carried out.Field test indicates that carbon dioxide foam fracturing technique can reduce the volume of water-based fracturing fluid flowing into gas reservoir,provide the flow-back energy for fracturing fluid,fasten fracturing fluid flow-back automatically and prolifically,as well as can reduce the second damage to formation and improve the fracturing effectiveness in low-permeability and low-pressure gas reservoir.

Key words: carbon dioxide, foam fracturing technique, low-permeability and low-pressure gas reservoir, reservoir damage, field test

摘要： 针对低渗透、低压气藏压裂改造中压裂液返排困难的问题,研究了CO₂泡沫压裂技术,分析了CO₂泡沫压裂过程中井筒和储层温度场变化对CO₂液气转化的影响,对提高CO₂泡沫压裂液的流变性、内相恒定与工艺措施等进行了室内研究.现场试验表明,CO₂泡沫压裂技术能减少进入地层的水基压裂液量,提供地层液体返排的能量,达到了压裂液自喷、快速、多排的目的,从而降低了压裂液对储层的二次伤害,提高了低渗透、低压气藏的压裂效果.

关键词: 二氧化碳, 泡沫压裂技术, 低压低渗透气藏, 储层伤害, 现场试验