Synthesis of erucic amide propyl betaine compound fracturing fluid system

Abstract

Compared with the traditional water-based fracturing fluid, the water-based clean fracturing fluid had the advantages of low friction, easy flowback and no residue. A kind of erucic amide propyl betaine (EAPB) was synthesized by using erucic acid and N, N-dimethyl-1,3-propanediamine as raw materials, and a clean fracturing fluid was furtherly constructed by combining EAPB with organic acid. The composition of the fracturing fluid system was determined according to the viscosity change of the system. Meanwhile, the temperature resistance, salt resistance, sand-carrying performance and micelle-breaking properties of the system were studied. The results showed that the optimum molar ratio of EAPB to sodium salicylate (NaSal) in fracturing fluid system was 50:9. The zero-shear viscosity could reach up to 129 Pa·s at 25 ℃. When the shear rate was 170 s−1 and the temperature was 80 ℃, the viscosity could keep above 60 mPa·s after continuous one-hour shearing. Furthermore, it had good sand-carrying and micelle-breaking performance. There was easy flowback and no residue after the micelle-breaking, which did low damage to the formation and achieved the effect of increasing oil and gas production. In addition, the average permeability damage rate of the fracturing fluid to the natural core of the reservoir in the target block was 6.07 %. This showed that the fracturing fluid system had the characteristics of low damage, which could effectively reduce the secondary damage after fracturing and play a certain role in reservoir protection. Therefore, it could be used as a clean fracturing fluid. The research results could provide guidance and reference for the fracturing fluid system in oilfield application.