Developing New Recyclable and CO2 Sensitive Amphiphile for Fracturing Fluid

With rapid development of unconventional shale gas and tight oil, hydraulic fracturing is playing a critical role in oil & gas exploitation and stimulation. Meanwhile, damage to the reservoir fracture and environmental contamination caused by fracturing flowback water has raised serious concerns. In this study, we develop a novel amphiphilic VES fracturing fluid that is not only rock formation friendly and environment benign but also can readily be reused, and with a gelling-breaking process be easily controlled by different gas conditions. We synthesized a CO2-responsive surfactant C(22)ZEA which can be used as a thickening agent for hydraulic fracturing fluid. The basic properties of the C(22)ZEA are studied. Then the different phase behaviour of this CO2-responsive fracturing fluid was investigated through rheological measurements under ambient and elevated temperature and pressure. The fluid-rock interaction was lastly studied in the core flooding tests. The good CO2 responsiveness and switchability in viscoelasticity portend the achievable reused of this VES fluid; most interestingly, this fluid exhibits noticeable shear tolerance and CO2 pressure responsive behaviors which has great potential to realize the reclamation of VES fracturing fluid, and the fracturing fluid exhibits better performance under supercritical CO2 condition.