pH-responsive clean fracturing fluid based on pseudo-trimeric surfactants

Viscoelastic surfactant fracturing fluids, also known as clean fracturing fluids, have attracted extensive attention in the field of hydraulic fracturing because of their advantages, such as complete gel breaking, no residues, and low formation damage. However, the complex synthesis process, high cost, and the inability to reuse have limited the practical application of clean fracturing fluids. Herein, a pH-responsive clean fracturing fluid with pH-regulated apparent phase and rheological behaviors was constructed based on the mechanism of pseudo-trimeric surfactant and wormlike micelles formed under specific pH conditions by N,N-dimethyl oleoaminde-propylamine and tricarballylic acid. The results show that the zero-shear viscosity of the fracturing fluid can reach more than 111.2 Pamiddots, and it can switch between a high-viscosity gel state and a low-viscosity aqueous solution state more than four times by adjusting pH. The constructed clean fracturing fluid is suitable for medium and low-temperature oil and gas reservoirs. The viscosity of the fracturing fluid is still higher than 500 mPamiddots after shearing at 60 degrees C and 170 s(-1) for 60 min. In addition, the fracturing fluid can be completely broken within 1 h, and the gel broken-fluid has low viscosity and no residues.

Automated summary

A pH-responsive clean fracturing fluid was developed based on the mechanism of pseudo-trimeric surfactant and wormlike micelles formed under specific pH conditions. The fluid can switch between high-viscosity gel state and low-viscosity aqueous solution state by adjusting pH, making it suitable for medium and low-temperature oil and gas reservoirs. After shearing for 60 minutes at 60 degrees C and 170 s(-1), the viscosity of the fluid remains higher than 500 mPamiddots.