Study on Nonionic Surfactant Gel Fracturing Fluid

Abstract

Two kinds of nonionic surfactants were synthesized to configure fracturing fluid that can make up for the inadequacy of cationic surface active agent which has damage to the formation. The effect of the surfactant concentration on the apparent viscosity was discussed in this paper. The shear resistance, heat resistant, sand-carrying performance and gel breaking of the fracturing fluid were evaluated as well. It was shown that 2% of the surface active agent which was synthesized by oleic acid could crosslink in aqueous solution with the help of cosurfactant, and the viscosity could remain in 40mPa·s at 60°C, 170s-1; 3% of the surface active agent which was synthesized by erucic acid could crosslink in aqueous solution with the help of cosurfactant, and the viscosity could remain in 45mPa·s at 90°C, 170s-1. The elastic modulus G'≥2 and viscous modulus G"≥0.3 at 25°C and 0.01~10Hz frequency range showed that the fracturing fluid had good viscoelasticity. In the condition of 30°C, 70°C, sand sedimentation rates were 0.02 mm/s, 0.57 mm/s and 0.04 mm/s, 0.72 mm/s, meaning that the carrying capacity was perfect. The systems could be broken with kerosene, the gel breaking liquid was clarified and had no residue. So the fracturing fluids were suitable for the low and medium-high temperature formation.