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从 8 0年代早期北美就开始采用以液态二氧化碳为基础的压裂液系统进行储层改造 ,1994年开始采用以液态二氧化碳 /氮气为基础的压裂液系统进行压裂。此压裂液已广泛应用于渗透率值在 0 1mD～ 10D之间的各种地层中 ,在 10 0 0多口井中进行了应用 ,其井深超过 30 0 0m ,井底温度在 10～110℃之间。此压裂液的物理和化学性质非常有吸引力。以前曾做了一些增加液态二氧化碳黏度的尝试 ,可都没有成功。本文描述了一种既能增加黏度又能保持液态二氧化碳非破坏性的新型压裂液 ,它是在液态二氧化碳中形成氮气泡沫。该压裂液使用的是一种不损坏地层的可溶性二氧化碳发泡剂 ,可以释放在大气中而不会污染环境。此压裂液不包括其他压裂成分 ,如水、乙醇或碳氢化合物。泡沫的形成遵循常规的发泡机理。该系统比典型液态二氧化碳压裂系统成本效率更高。
Since the early 1980s, North America began to use a liquid carbon dioxide-based fracturing fluid system for reservoir reconstruction. In 1994, a fracturing fluid system based on a liquid carbon dioxide / nitrogen gas was used. The fracturing fluid has been widely used in various formations with permeability values between 0 1mD and 10D and has been applied in more than 10 0 wells with a well depth of over 30 0 m and a bottom hole temperature of 10 to 110 ° C between. The physical and chemical properties of this fracturing fluid are very attractive. Previous attempts to increase the viscosity of liquid carbon dioxide have been unsuccessful. This article describes a novel fracturing fluid that increases viscosity and maintains non-destructive properties of liquid carbon dioxide. It forms a nitrogen foam in liquid carbon dioxide. The fracturing fluid uses a soluble carbon dioxide blowing agent that does not damage the formation and can be released into the atmosphere without contaminating the environment. This fracturing fluid does not include other fracturing components such as water, ethanol or hydrocarbons. Foam formation follows the conventional foaming mechanism. The system is more cost-effective than typical liquid carbon dioxide fracturing systems.