Study On Performance And Preparation Of Microemulsion Corrosion Inhibitor For Coiled Tubing In Acid Fracturing

Fracture acidizing technique is an important well stimulation of oil and gas fields,the application of coiled tubing technology significantly improved the working efficiency and reduce the operation cost.However,there are serious corrosion problems existing in the actual construction,in view of the problems of current corrosion inhibitor technology about poor film-forming stability,poor persistence and the stratigraphic loss.This paper developed a kind of microemulsion corrosion inhibitor which having enduring corrosion resistance.There will be important practical significance to improve the service life of the coiled tubing.After the optimizing experiments,the mannich are selected as the main agent of microemulsion corrosion inhibitor by static weight-loss method.Based on surfactant A,surfactant B and white oil as the main raw materials,the reasonable formula of homogeneous phase microemulsion is optimized by the quasi ternary phase diagram method,fixed oil/water mass ratio of 1:1,get the optimal amount of components:c_A=8.19%,c_B=8.19%,c_n-butanol=9.83%.Comprehensive evaluation the acid soluble and temperature resistance of microemulsion,optimizating the best feeding ways with the index of emulsification time.The concentrations of microemulsion and mannich are optimized as the main agent HS based on corrosion rate,using the method of static weight-loss.On the basis,the synergistic and solubilizer are optimized by combination technology,and then we get the basic formula of the HSL-1 microemulsion corrosion inhibitor:main agent HS:surfactant E:XI:YCl=15:4:2:1;When the mass concentration of HSL-1 is 1.5%,the corrosion rate of fresh acid is up to3.235 g/?m²·h?,and the corrosion rate of spent acid is up to 0.458 g/?m²·h?.Referring to the professional standard,comprehensive performance evaluation of the HSL-1 microemulsion corrosion inhibitor is made.The results show that,the composite system has excellent performance of compatibility,acid-resistance and temperature resistance,and has low damage on the core permeability,which has a good prospect.The corrosion and corrosion inhibition mechanism of coiled tubing is studied in combination with the methods of X-ray diffraction?XRD?.Scanning electron microscopy?SEM?and electrochemical corrosion,polarization curves show that the HSL-1 corrosion inhibitor is a kind of mixed type corrosion inhibitor which is given priority to control corrosion of cathodic process.The microemulsion effectively control the release speed of the corrosion composition through the O/W structure,so as to achieve enduring corrosion effect.