Abstract:
Objective Aiming at the problems of poor shear resistance of polymer and the influence of deep formation viscosity retention in conventional chemical flooding system, wormlike micelle oil displacement technology was studied.
Methods Using betaine surfactant monomer (PSM), N, N-dimethylpropylene diamine and other raw materials, by two-step reaction of amidation and quaternization, the wormlike micellar surfactant for oil displacement with viscoelasticity and interfacial activity was synthesized under the conditon of reduced pressure spin drying. The molecular structure, rheological properties, microstructure, shear resistance, salt resistance, interfacial tension and oil displacement characteristics of wormlike micelle were investigated.
Results The structure obtained by NMR was consistent with the target product. Wormlike micelle has good viscosity increasing (mass fraction 0.30%-0.50%, apparent viscosity 10-50 mPa·s, 7.34 s-1), salt resistance (< 100 000 mg/L) and the ability to reduce oil-water interfacial tension (10-2 mN/m). The core displacement experiment results showed that the wormlike micelle has stronger oil displacement ability than conventional polymer, and the EOR was increased by 11.7%. Field well group test increased oil by 2 700 m3.
Conclusions Wormlike micelle oil displacement technology can be used as an efficient oil displacement agent in offshore high water-cut reservoirs to effectively increase oil rate and reduce water production.