The Corrosion Inhibitor Screening And Evaluation In The Process Of Air Foam Flooding

Air foam flooding is a newly-developed EOR technique in recent years. It has rich sources and low cost, besides the traditional gas injection effect, the add of foam can also prevent the breakthrough of gas, control the fluidity, expand the conformance efficiency. Therefore, the air foam flooding technique is widely used in the exploitation of light and low permeability oil reservoir. However, in the flooding process, with a massive injection of air foam, dissolved oxygen corrosion of the injection well is quite serious. And then with the combust reaction and low temperature oxidation (LTO) affect occured, oxygen gradually consumed and a large number of carbon dioxide generated near the production wells, which caused very serious corrosion.Zhongyuan HuWuKuai oil field is a high temperature and high TDS reservoir, the average temperature is over80degree, salinity is as high as20x104mg/L, calcium and magnesium content is also very high. Before the air foam flooding, first we choose the0.2%of NB95as the foaming agent based on the reservoir condition. The paper usd this foaming system as corrosive medium, under high temperature and high TDS condition, mainly discussed the dissolved oxygen corrosion of injection wells and carbon dioxide corrosion of production wells, carried out the following studies:(1) According to the process of dissolved oxygen corrosion, by comparing the performance of various corrosion inhibitors, we selected three kinds of corrosion inhibitors which can fit the reservoir conditions by weight-loss experiment:CT2-17、WY4-17+ZnSO4. LX8-27+ZnSO4and also decided their best concentration. Then we evaluated their performances under different temperatures、pressures、TDS and calcium ion concentrations.(2) According to the process of carbon dioxide corrosion, we also evaluated some kinds of acid corrosion inhibitors by weight-loss experiment, and find out that the three kinds of corrosion inhibitors we chosed earlier had good performance under carbon dioxide corrosion. Then we also evaluated their performances under different temperatures. pressure、TDS and calcium ion concentrations.(3) In order to study how the corrosion inhibitors effected on the foaming system, we compared the foam volume and half value period before and after the add of corrosion inhibitors by Waring Blender method.The experimental results showed that the affect of corrosion inhibitor systems on foam performance is small. After one-month aging under90degree, the foam volume and half value period nearly didn’t change. The Interfacial tension experiment testing results shows:for the Zhongyuan oil field, with or wihout the corrosion inhibitors, the interfacial tension didn’t changed much.Based on the corrosion problems during air foam flooding of Zhongyuan HuWuKuai oil field, this paper has selected three kinds of temperature and salt resisting corrosion inhibitor systems which can be effective under both dissolved oxygen corrosion and carbon dioxide corrosion, and we evaluates their performances under different temperatures、pressures、TDS and calcium ion concentrations, then we study their effect on the foaming system. This research has important theoretical significance and practical application value in solving the corrosion problem in air foam flooding.