The Research Of Hydrazine Modified As Acidizing Corrosion Inhibitor

Acidizing is an important EOR technical measure in Oilfield, however, acidizing can cause metal corrosion, and lead to serious economic losses and security risks, when the acidizing fluid flows into the formation, the geological will be damaged, and environmental will be polluted.Therefore, for the oil industry, the most common and effective way is to add inhibitor into acid fluid during acidizing treatment. Based on field practice, using inhibitor is an effective method of metal corrosion protection, the process of the method is simple, low-cost, and has strong adaptability. Therefore, the development of corrosion inhibitor with good performance, high temperature resistance, low cost and environmental protection is particularly important.For the domestic synthetic acidizing corrosion inhibitors, the amine is often used as raw materials. The hydrazine is a special class of amine, its molecular structure containing nitrogen atoms with two lone pair electrons, the lone pair electron is easy to form the coordination bond with empty d-orbital of the transition metal atom lone, and then generated a stable chelate. And the hydrogen on the nitrogen easily substituted by other groups, it is possible to introduce a non-polar group, and hydrophobic protective layer formed on the metal surface, and which play a role in isolation. So hydrazine compounds have structural advantages when it is used to synthesize inhibitor, just hydrazine modified into Mannich bases with stability structure, well anti-temperature, acid resistance performance, which will have a very good practical significance and application prospects.Based on Mannich reaction in this article, X hydrazine and Y hydrazine were modified into XJ and YJ series of Mannich bases corrosion inhibitors. Reference to the oil and gas industry Standard SY5405-1996in the People’s Republic of China "test methods and evaluation of inhibitor performance with acidification", evaluated corrosion inhibition、characterized structure、researched corrosion inhibition mechanism by Electrochemical methods. The main content of the article are the following four parts:(1) Synthesis of XJ and YJ series of Mannich bases corrosion inhibitors and performance evaluation.XJ series of Mannich bases were synthesized with X hydrazine, formaldehyde and acetophenone. In15%hydrochloric acid system, the optimum synthesis conditions are follow as:the molar ratio of aldehyde to amine is3.3, the molar ratio of ketone to amine is3.0, the pH is4, the temperature is80℃, the synthetic time is4h, and the corrosion rate is0.265g·m-2·h-1. In conventional mud acid system, the optimum synthesis conditions are as follows:the molar ratio of aldehyde to amine is3.1, the molar ratio of ketone to amine is3.3, the pH is3, the temperature is60℃,the synthetic time is5h, and the corrosion rate is0.408g·m-2·h-1.YJ series of Mannich bases were synthesized with Y hydrazine, benzaldehyde and acetophenone. In15%hydrochloric acid system, the optimum synthesis conditions are as follows:the molar ratio of aldehyde to amine is3.1, the molar ratio of ketone to amine is3.0, the pH is2, the temperature is60℃, the synthetic time is4h, and the corrosion rate is0.520g·m-2·h-1. In conventional mud acid system, the optimum synthesis conditions are as follows:the molar ratio of aldehyde to amine is2.9, the molar ratio of ketone to amine is2.8, the pH is2, the temperature is80℃, the synthetic time is5h, and the corrosion rate is0.503g·m-2·h-1.Comprehensive view, when the temperature is60℃, the corrosion inhibition of XJ series of Mannich bases is better than YJ series of Mannich bases in15%hydrochloric acid system and conventional mud acid system.Based on the static coupon weight loss method, evaluated corrosion inhibition of XJ series of Mannich base and YJ series of Mannich base in different acid and different temperature. The results showed both of the two kinds of Mannich bases had good corrosion inhibition.Within the experimental temperature range of40-90℃, the corrosion rate of XJ series of Mannich bases is below3g·m-2·h-1, it is reach to the primary standard of the oil and gas industry standards.The corrosion rate of YJ series of Mannich bases is below2g·m-2·h-1, it is reach to the primary standard of the oil and gas industry standards, In the concentration range of12%-28%hydrochloric acid, the corrosion rate of XJ series of Mannich bases and YJ series of Mannich bases is below1.5g·m-2·h-1, two kinds of Mannich bases have good acid resistance.According to comprehensive comparison, the anti-temperature of YJ series of Mannich bases is better than XJ series of Mannich bases.(2) Structure identification of the two series of Mannich base corrosion inhibitorsThe two synthetic products were characterized by infrared spectrometry, the results showed that, the IR spectra of XJ corrosion inhibitor and YJ corrosion inhibitor under optimum synthetic conditions contained characteristic peak, so the synthesized products are our target products. The results of Elemental analysis also proved that the synthesized products are the target products.(3) Study on electrochemical mechanism of Mannich bases as acidizing corrosion inhibitors Based on the electrochemical workstation test system, the corrosion inhibition mechanism of XJ Mannich bases and YJ Mannich bases as acidizing corrosion inhibitors was analyzed by polarization curves and AC impedance. The results showed that both of XJ and YJ corrosion inhibitors are mixed-controlled corrosion inhibitor mainly inhibiting positive pole processes, when the concentration of corrosion inhibitors increased, the corrosion rate decrease.The trend of AC impedance spectroscopy is consistent with the trend of polarization curve.(4) Study on adsorption behavior of XJ Mannich bases as acidizing corrosion inhibitorAdsorption behavior of XJ Mannich bases corrosion inhibitor on the surface of N80steel is conform to Langmiur adsorption isotherm, The adsorption process is spontaneous,endothermic and entropy increase process. When the temperature increased, the corrosion rate increased, the adsorption quantity of corrosion inhibitor on the surface of N80steel increased.