Experimental investigation on rheological properties and friction performance of thickened CO2 fracturing fluid

Abstract For the purpose of guiding the field treatment of CO 2 stimulation, the experimental investigation on rheological properties and friction performance of thickened CO 2 fracturing fluid system is performed in the pressure range of 10–30 MPa and the temperature range of 0–100 °C by using high-parameter fracturing fluid test system. The correlations for thickened CO 2 fracturing fluid rheological parameters have been obtained. The results present that the effective viscosity decreases with increasing shear rate and the change below 500 s − 1 is more sharp. The effective viscosity decreases from 20 mPa s to 8.2 mPa s with increasing temperature at 20 MPa, 3.0 wt% and 393 s −1 , and shows a small increase with increasing thickener concentration. Temperature and shear rate influences on the rheological properties are larger in various influencing factors. The frictional resistance coefficient of the thickened CO 2 fracturing fluid decreases from 0.69 to 0.12 with increasing flow velocity at 20 MPa, 15 °C and 3.0 wt%, and levels off as the flow velocity reaches 0.4 m/s. The friction resistance coefficient presents a decrease trend with increasing temperature, and increases with increasing pressure or thickener concentration at the constant temperature, however, the change range is smaller.