A New, Low Corrosive Fluid to Stimulate Wells with Carbon Steel Tubular and Internals

Abstract

Abstract For many reasons acidizing treatments represent a real challenge to the oil and gas industry. On one side acidizing can significantly improve the productivity of the well, but on the other side the intrinsic corrosive character of the acids form a severe threat to the well's integrity. Therefore traditional acidizing treatments with fluids involve significant loadings of corrosion inhibitors and corrosion inhibitor intensifiers to help mitigate the corrosion. However, the additives can cause their own damage to the formation, reduce overall effectiveness of the acidizing fluid, and come with significant additional costs to the overall acidizing program. Recently studies with a new environmentally friendly stimulation fluid, glutamic acid diacetic acid (GLDA), were presented for both carbonate and sandstone reservoirs. The studies have shown that GLDA can dissolve calcite & dolomite, does not destabilize clays particles, and can significantly improve permeability in both carbonate and sandstone formations across wide field conditions. In the present paper the corrosion rate of GLDA is compared with other chelates and simple organic acids that are used for carbonate dissolution, such as hydroxyethylethylenediaminetriacetic acid (HEDTA), acetic, citric and formic acid. All corrosion tests were conducted at high temperature and pressure and extended for up to 6 hour at temperature and pressure. The results show that GLDA at 20 wt% has the least impact on low carbon steel, in comparison to the other stimulation fluids examined in this study. A very minimal amount of corrosion inhibitor loading was needed to keep the corrosion rate below the acceptable rate for GLDA, even at elevated temperatures or in the presence of corrosive gases like H2S and CO2. On more corrosion resistant Cr-based metals, like Cr-13 and duplex, the corrosion rate of GLDA is far below the acceptable limit with no corrosion inhibition even at 300°F. Based on the results, GLDA solutions can be used to stimulate carbonate and sandstone wells completed with various types of metallurgies with no or very minimal amount of corrosion inhibitors and effectively maintain the integrity of the tubular & internals.