Experimental study on convection heat-transfer characteristics of BCG-CO2 fracturing fluid

A BCG-CO2 fracturing fluid system is especially suitable for shale gas stimulation because it has many advantages, including minimizing water consumption, reducing damage to the formation, and recovering more rapidly and efficiently. A major objective of this experimental study is to ascertain the convection heat-transfer characteristics of a BCG-CO2 fracturing fluid system. A high-parameter foam fracturing fluid test system was adopted in this study. The measurement of convection heat transfer is based on the double-wall heat-transfer theory. Through experimental research, the correlations for BCG-CO2 fracturing fluid convection heat transfer have been obtained under different foam qualities. The average error of the fitting formula for all experimental data is 10.7%. The results indicate that the convection heat-transfer coefficient decreases with increasing temperature, with an average decrease of about 10%. The convection heat-transfer coefficient shows a decreasing trend with increasing foam quality. There is a linear relationship between the convection heat-transfer coefficient and shear rate, and the shear rate has the most pronounced effect on convection heat-transfer characteristics. The results of this study can be used to calculate heat-transfer parameters to determine the temperature field of BCG-CO2 fracturing fluid flow in fracturing design, and they are significant for the engineering application of BCG-CO2 fracturing fluid.