Velocity Guidelines for Avoiding Erosion-Corrosion Damage in Sweet Production With Sand

CO₂ corrosion in carbon steel piping systems can be severe depending on a number of factors including CO₂ content, water chemistry, temperature, and percent water cut. For many oil and gas production conditions, corrosion products can form a protective scale on interior surfaces of the piping. In these situations, metal loss rates can reduce to below design allowances. But, if sand is entrained in the flow, sand particles impinging on pipe surfaces can remove the scale or prevent it from forming at localized areas of particle impingement. This process is referred to as “erosion-corrosion” and can lead to high metal loss rates. In some cases, penetration rates can be extremely high due to pitting. This paper combines laboratory test data on erosion-corrosion with an erosion prediction computational model to compute flow velocity limits (“threshold velocities”) for avoiding erosion-corrosion in carbon steel piping. Also discussed is how threshold velocities can be shifted upward by using a corrosion inhibitor.