Research And Application Of Composite Corrosion Inhibitor Foaming Agent For Foam Drainage In Sichuan-Chongqing Sour Gas Field

In order to solve the problem of serious bottom liquid loading and corrosion in Sichuan and Chongqing sour gas field,and the incompatibility between foaming agent and corrosion inhibitor,the interaction between foaming agent and corrosion inhibitor was studied,and the corrosion inhibitor and foaming compound agent was developed,and the performance of corrosion inhibitor and foaming compound agent was evaluated.The effects of temperature,pressure and well depth on foam drainage performance were discussed,and the application process of corrosion inhibitor and foaming compound agent and the rapid evaluation method of on-site corrosion were developed.The paper provided a new idea for the drainage operation of sour gas field.The interaction between foaming agent and corrosion inhibitor for foam drainage was clarified through the matching experiments of different types foaming components and corrosion components.The oil solvents of the corrosion inhibitors will affect the foam drainage performance,and will form emulsions after mixing with the foaming agent.The mixture of foaming and corrosion components with opposite ion types may produce precipitation,and greatly affect the foam drainage performance.Different types of functional groups also affect each other,resulting in poor foam drainage performance and corrosion resistance.Based on the interaction between the foaming components and the corrosion retardant components,this paper optimizes a wide range of suitable foaming components to be combined with the selected water-soluble corrosion components,and successfully develops a corrosion inhibitor and foaming compound agent CT5-20.The foaming capacity in the formation water is 108 to 230 mm,the foam stability is 22 to 50 mm,the liquid carrying capacity is 130 to 142 mL/15 min,and the corrosion rate is 0.0158 to 0.0535 mm/a.The agent has a multifunctional function and has a good anti-corrosion effect while satisfying foam drainage.At the same time,the foam drainage performance of eorrosion inhibitor and foaming compound agent CT5-20 under different temperature,pressure and depth conditions was investigated based on the different well bottom temperature,pressure and well depth of Sichuan and Chongqing sour gas field.The study found that the pressure has no significant effect on the foaming ability of CT5-20,but the foam stability is greatly affected by the pressure,and the high pressure is more conducive to the foam stability.The temperature has a certain effect on the foaming ability,but the overall effect is not significant..The foam stability below 135? changes slightly with temperature,while the foam stability above 135? gradually decreases with temperature increase.The depth of the well has no significant effect on the foaming ability,and has an effect on the foam stability,but the effect is small.According to the performance characteristics of corrosion inhibitor and foaming compound agent CT5-20,combined with the field situation of Sichuan and Chongqing sour gas field,the field application process of corrosion inhibitor and foaming compound agent CT5-20 is developed.corrosion inhibitor and foaming compound agent is injected from the casing annular,and the accompanying defoaming agent is injected in front of the separator.The foam drainage effect is evaluated by the pressure between tubing and casing,gas production,and water production before and after foam drainage.The anti-corrosion effect is comprehensive evaluated by the iron ion analysis method and the corrosion coupon method.In this paper,corrosion inhibitor and foaming compound agent CT5-20 has carried out field tests in seven wells including Q28,T18,T19,D002-1,T016-1,W36-1 and M50 to increase the gas production by 4.95 × 104m3/d and increase water produced by 4.53 m3/d.The iron ion content in the produced water decreased by 59%to 81%.and the corrosion rate can be controlled below 0.076 mm/a by the adjustment of the amount of the agent,which has achieved good anti-corrosion and drainage effects.To a certain extent,it solves the problem that the foam drainage and chemical anti-corrosion can not be combined.