Rheological properties study of foam fracturing fluid using CO2 and surfactant

In this study, the macro properties of a CO2 fracturing fluid were studied experimentally. A detailed experimental investigation has been conducted on the rheology of the CO2 clean-fracturing fluid by using a large scale experiment system. A fluid model using Fluent software was adopted to simulate the gas distribution and fully developed state of the CO2 fracturing fluid. The experimental results show that the CO2 fracturing fluid is shear thinning and the rheological properties can be described by the power-law model. As well, the character of this fluid differs greatly from that of single phase non-Newtonian fluid because of its formation of foam and the structure of its external phase. It was also found that the viscosity of CO2 fracturing fluid was proportional to the increment of foam quality and pressure, which, however, was inversely proportional to the increase of temperature and shear rate. Moreover, through analysis of the effects of different factors on the rheology characteristics, correlations of its rheological parameters were obtained.