Introducing hydroxyl into cationic surfactants as viscoelastic surfactant fracturing fluid with high temperature resistance

The viscoelastic surfactant (VES) fracturing fluid is new fracturing system, which is primarily made up of viscoelastic surfactant and some other auxiliaries. The traditional VES fracturing fluid has the obvious advantages in gel breaking, flowing back, carrying sands, etc. However, they are centered largely in the aspects of medium and low temperature system. In this paper, the work is focus on the need for the VES fracturing fluid with high temperature resistance. In the experiment, four kinds of viscoelastic surfactants with hydroxyl were firstly synthesized, which were named C 14 -1, C 16 -1, C 14 -2 and C 16 -2 respectively. Then the formulation of VES fracturing fluid was determined in accordance with the apparent viscosity of solution, and the formulation was that concentration of C 16 -2 and NaSal were 2.5% and 1% respectively. It was found that the VES fracturing fluid has excellent effectiveness via testing properties of temperature resistance, shear stability, sand-carrying and gel breaking. When the temperature of system was 144°C, the apparent viscosity of the VES fracturing fluid was 25 mPa s, which could demand the requirements of carrying sands as well as support agents, and it could resist high temperature well. It is also observed that the VES fracturing fluid is the pseudoplastic fluid, which contributes to getting the cracks with excellent negotiability.