Experimental Study on Frictional Resistance Characteristics of CO2-Emulsified Viscoelastic Surfactant Fracturing Fluid

Rheological properties and friction resistance properties of CO2-emulsified viscoelastic surfactant fracturing fluid were investigated on the large-scale test loop of foam fracturing fluid. When the velocity is below 2.8 m·s-1, the friction pressure drop gradient gradually decreases with the increase of foam quality, however, when the velocity is above 2.8 m·s-1, the friction pressure drop gradient of VES-CO2 with higher foam quality is higher than lower foam quality. In addition, frictional pressure drop gradient of the pure CO2 is higher than the VES-CO2 fracturing fluid system when the velocity is more than 1.6 m·s-1. And frictional resistance coefficient decreases with the increase of foam quality and increases slightly with the increase of temperature. Experimental correlation between frictional resistance coefficient and Reynolds number is obtained and has high precision.