Research On Corrosion And Scale Inhibition Of Carbon Dioxide Oil-displacing Produced Fluid

CO₂oil displacement technology is a method that can reduce the water content of produced fluid and improve oil recovery,but it can also cause corrosion and scaling.A similar problem occurred in an oil field in North China.The Corrosion Inhibitor was synthesized from oleic acid and diethylenetriamine.It was characterized by infrared spectroscopy.By comparing it with five commercially available corrosion inhibitors such as hydroxyl phosphate type and double quaternary ammonium salt type,its effect was the best.Taking the oilfield produced fluid as the evaluation medium,the corrosion inhibition rate was 54.02%at 100 mg·L^-1,60℃and CO₂partial pressure of 2 MPa,but it could not meet 70%corrosion inhibition rate of the industry requirements.In order to facilitate the production,it was optimized that when the molar ratio of oleic acid and diethylenetriamine was 2:3,the yield was the highest.The imidazoline oleate was binary compounded with seven corrosion inhibitors such as ammonium chloride and thiourea.Thiourea and double quaternary ammonium salt have synergistic effect with imidazoline oleate.The corrosion inhibition rates at 100mg·L^-1were 52.1%and 57.8%respectively,but still less than 70%.Secondly,it was modified by quaternization,phosphatization and vulcanization.It was found that the inhibition rate of phosphatized imidazoline oleate could reach 74.15%at 50 mg·L^-1.Polarization curve test showed that imidazoline containing phosphooleic acid was an inhibitory anode type;AC impedance experiment showed that it could hinder charge transfer,and the conclusion was consistent with the static weight loss method.Ts-50611 with scale inhibition rate of 98.9%was selected from 17 kinds of commercial calcium carbonate scale inhibitors.The best effect was that the scale inhibition rate and corrosion inhibition rate reached 98.98%and 91.25%respectively.The field application showed that the effect was good.Figure 22;Table 34;Reference 64...