Experimental Study on Rheology of Sand-content Fracturing Fluids

Fracturing fluids with proppants are commonly used in field operations for better fracturing efficiency. Study on the rheological pattern of sand-content fracturing fluids is expected to provide a better theoretical basis on which accurate prediction of the sand carrying capacity of fracturing fluids in pipe and in fracture can be made. Taking the fracturing fluid and the sands in it as a whole, the mixed fluids were studied for the patterns and mechanisms of the change of apparent viscosity with shearing rate. It was found that after mixing with proppants, the viscosity of the mixture of a fracturing fluid and the proppants under certain shearing condition is lower than the viscosity of the fracturing fluid itself, the apparent viscosity first decreases with shearing strength and then increases, showing a "V" pattern. This is the result of the synergy between the change of the internal structure of the solid-liquid mixture and the disturbance of the proppant particles. The special rheological behavior of the sand-content fracturing fluids is also influenced by the concentration and particle size of the proppant and the liquid temperature. At high shearing rate, the collision of proppant particles is frequent, and the apparent viscosity of the sand-content fracturing fluid increases with the concentration of the sand. At low shearing arte, the apparent viscosity of the sand-content fracturing fluid first decreases and then increases with the concentration of the sand because of the additional shearing action of the sand particles, and the viscosity of the sand-content fracturing fluid is reversely related with the particle size of the proppant and the temperature of the fluid.