Paper: Colied Tubing Acid Corrosion Laboratory VS. Field

Use of Coiled Tubing in underbalanced acid washing is becoming more prevalent in carbonate wells with H2S production. Corrosion testing under pressures and temperatures representing downhole conditions is used to qualify a corrosion inhibitor loading. Sour conditions warrant testing with differing amounts of H2S in the gas phase. Safety factors, weight loss and pitting guidelines are employed in the inhibitor design to ensure continued integrity of Coiled Tubing. The thin wall of these tubulars makes corrosion control of the utmost importance. Evaluations of Coiled Tubing after acid treatments examines the surfaces for defects and uses the perlite layer at the concentric center of the tubing wall to determine material losses. Comparisons of laboratory tests to effects on Coiled Tubing, used to treat wells producing from 0 to 60% H2S at temperatures of 75_ to 110_C (167_ to 230_F) are presented. Specifically material deterioration and surface evaluations are compared.