Research On Corrosion To The Injection System, Formation Damage Evaluation And Countermeasures Of Air Foam Flooding

The air foam flooding has achieved good exploitation results in YanChang oilfield, but its corrosion to the inject system and injure to the oil layer are the bottlenecks which restrict the application of this technology. The key problems what need to be resolved now are evaluate the system according to the corrosion Mechanism and the degree of hurt, select the proper inhibitor, discuss the compatibility between inject media(foam, air and surface water) and oil layer, evaluate the hurt degree to the layer of air foam flooding and take corresponding measures.According to the results of research on injection system corrosion, we found that the corrosion which exist in the Ganguyi oilfield injection system is mainly Fe2O3 and the quantity of the others including CaCO3,FeS、SiO2、Al2O3 is relatively small. The corrosion test showed that air pressure has great impact to corrosion and high pressure could accelerate the corrosion process, this phenomenon related to the increase of partial pressure of oxygen in corrosion media. The more times bubble liquid and air injected alternating injecte, the higher corrosion rate. Frequent injection make water and oxygen exist together. Higher temperature accelerate the speed of corrosion and diffusion rate of oxygen in air. Greater humidity of the injected air,higher corrosion rate. Inhibitor CT2-17 and sacrificial anode protection laws could be used to protect the injection system in Ganguyi Oilfield.In terms of layer damage, low-temperature oxidation reactionsair could react between air and formation oil and release a great amounts of CO2. Acidic carbon dioxide can dissolute the porous media to enhance reservoir permeability, and the solution more likely to scaling when the environment changes. The more important is that the layer prone to blockage formation of bacteria, so the antiseptic should be mixed in the solution when injecting air foam system. The antiseptic could greatly reduce the extent of corrosion. The extent of corrosion blowing agent is relatively light and the Shichuang foaming agent C has better performance. This article have important guiding significance to the corrosion mechanism of air foam flooding in Ganguyi oilfield and effective protective measures should be taken.