Preparation and Performance Evaluation of 180 ℃ Viscous Acid System
In the process of oil and gas exploitation and production,thickened acid is a commonly used working fluid in acid fracturing.The main performance supporters of thickening acid are thickening agent and corrosion inhibitor.The role of thickening agent is to increase viscosity and reduce acid rock reaction rate,and the role of corrosion inhibitor is to protect equipment.The common problem in the thickening acid is that the thickener's own temperature resistance and acid resistance are poor,resulting in the failure to achieve the purpose of deep acidification at high temperature.In addition,the current high temperature corrosion inhibitor for acidification has poor compatibility with the acid system and insufficient anti-corrosion ability.Therefore,the acidification of carbonate reservoirs in high temperature deep wells is more difficult.A series of polyacrylamide cationic thickeners with temperature and acid resistance were designed and prepared,and their basic properties were studied.At the same time,the corrosion inhibitor suitable for high temperature acid solution was screened out,and the high temperature resistant thickening acid was formed in combination with other additives to further study the performance of thickening acid.The results show that the self-made SH4 thickener has excellent acid resistance and viscosity increasing performance.In 20％hydrochloric acid,the viscosity of 0.6％thickener can reach 59.88 mPa·s.The corrosion rate of N80 steel sheet is only 41.614 g/(m2·h)after high temperature and high pressure dynamic corrosion test at 180 ℃.The viscosity of the thickened acid system remained at 33.258 mPa·s at 180℃and 170 s-1,which prove that it had strong temperature and shear resistance and could be used for high temperature acidification.
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