Preparation and Performance Study of a Viscosity‐Reducing Oil Displacement Agent for Heavy Oil in Gudao Reservoirs at Shengli Oilfield

To address the issue of low waterflood recovery rates in ordinary heavy oil reservoirs on Gudao, oleamide propyl sulfonate betaine (PKO‐1) was synthesized using oleic acid, 3‐dimethylaminopropylamine, and sodium 2‐bromoethanesulfonate as raw materials. The intermediates and products were structurally characterized using infrared spectroscopy and 1 H nuclear magnetic resonance. A viscosity‐reducing system, P7Y3, was constructed using PKO‐1 and isopropanol. The viscosity reduction rate, interfacial tension, contact angle, and anti‐adsorption properties of P7Y3 were tested. Performance testing indicated that at an oil‐to‐water ratio of 8:2 and a temperature of 70°C, a P7Y3 concentration of 0.3 wt% achieved a viscosity reduction rate of 95.47%. Following the addition of 1800 mg/L polyacrylamide, the viscosity reduction rate remained above 80%. At a P7Y3 mass concentration of 0.3 wt%, the oil–water interfacial tension was minimized to 6.0 × 10 −3 mN/m, with a contact angle of 46.3° and an adhesion work of 1.86 × 10 −3 mJ/m 2 . The reduction in adhesion work reached 99.18%. When the P7Y3 mass concentration ranges from 0.2 to 0.5 wt%, the adsorbed oil–water interfacial tension can reach 10 −2 mN/m.