Feasibility analysis on coiled-tubing jet fracturing with supercritical CO2

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 conclusions 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.