Study on Corrosion Behavior of Carbon Steel Oil Casing Materials in Acidizing and Fracturing Environment of Oilfield

Abstract

For clarifying the influence of fresh acid and residual acid on the corrosion performance of tubing materials and the adaptability of materials in an acid fracturing environment in a certain oil field， the corrosion damage development trend， pitting sensitivity in the whole process of acidizing and corrosion morphology characteristics of P110 and C110 tubing materials under different conditions were analyzed by corrosion weight loss method and three-dimensional stereo optical microscope observation， and the acidizing corrosion inhibitor was optimized.Results showed that as the acidification temperature of fresh acid gradually increased， the degree of material corrosion tends to increased.When the temperature was ≥180 ℃， the average corrosion rate of C110 was vcorr ＝127.7 g/(m2·h)， while the average corrosion rate of P110 was vcorr ＝407.0 g/(m2·h)， which is much higher than the index requirement.When the simulated fresh acid temperature was 100 ℃，pitting nucleation occurred on the material surface.As the temperature increased， the pitting sensitivity gradually increased.In the residual acid environment at ultra-high temperature of 180 ℃， both C110 and P110 materials suffered extremely severe corrosion.Furthermore， the corrosion inhibitor in the acidizing fluid component was obviously ineffective under high temperature conditions， resulting in serious corrosion damage to the pipes in the residual acid flowback environment.The optimized modified manene alkali acidizing corrosion inhibitor significantly slowed down the corrosion rate of the material through the formation of a multilayer adsorption film， and the corrosion inhibition rate was 89.4%in a high temperature fresh acid environment at 180 ℃.

Keywords

• acid fracturing； p110， c110 tubing materials； corrosion damage； pitting corrosion； acidizing corrosion inhibitor； high temperature and high pressure