超临界CO_2连续油管喷射压裂可行性分析

Feasibility analysis on coiled-tubing jet fracturing with supercritical CO_2

水力压裂增产技术在非常规油气藏的开发中承担着重要的角色,但在储层和环境保护方面都存在一些问题,而超临界CO2连续油管喷射压裂技术有望解决这些问题,成为未来非常规油气资源高效开发的新型压裂方法。通过分析超临界CO2的特性以及超临界CO2射孔能力和射流增压效果可知:超临界CO2射流比水射流的射孔能力强,射流增压效果好,可在较低的压力下实现喷射射孔和压裂;超临界CO2流体的渗透能力强,易渗入储层中的孔隙和微裂缝,在储层中产生大量微裂缝网络,提高油气采收率;将超临界CO2作为压裂流体,不仅可以避免黏土膨胀等储层伤害的发生,而且还能提高增产效果,尤其适合非常规油气藏的增产改造。在此基础上提出了超临界CO2连续油管喷射压裂的流程,为该技术的研究和应用提供了指导。

Hydraulic fracturing technique plays an important role in the development of unconventional oil and gas reservoirs, but it is facing some problems from the aspect of reservoir and environment protection. Coiled-tubing jet fracturing with supercritical CO2 （SC-CO2） is expected to be a solution to these problems and becomes a new and efficient technique for developing the unconventional oil and gas resources. By analyzing the properties of SC-CO2 and its rock breaking capability and pressure boosting effect, some conclu- sions can be drawn as follows： The rock breaking capability and pressure boosting effect of SC-CO2 jet is stronger than water jet, so the jet perforation and fracturing process can be accomplished with a lower pressure. The infiltration capacity of SC-CO2 is so strong that it can infiltrate into the formation easily and cause a network of interconnecting fracture, enhancing the recovery of oil and gas. When SC-CO2 is utilized as the fracturing fluid, formation damage, such as clay swelling, can be avoided, and it can improve the stimulation effect with its unique properties. So it is especially appropriate for the fracturing stimulation of unconventional oil and gas reservoirs. Finally, the operation procedure of coiled tubing jet fracturing with SC-CO2 was put forward, which provided guidance for the research and application of the technique.