ABSTRACT
Completion designs for deep water high pressure wells commonly require corrosion resistant alloy (CRA) tubing grades with minimum specified yield strengths of 125 ksi to resist against high tensile and collapse loads as well as corrosive reservoir fluids. The types of alloys considered for such well designs and corrosive environments are 17%Cr and super duplex stainless steels (UNS(1) S39274).
On completion of these wells the perforated pay zone may require acid stimulation to remove debris and therefore permit unrestricted hydrocarbon flow. Also later in the well life, carbonate scale may deposit in the completion which needs to be removed with a scale dissolver treatment.
A corrosion testing program aimed at evaluating stimulation acid/scale dissolver packages was designed and performed to determine which package(s) were least corrosive and acceptable for use with wells constructed with 17%Cr and super duplex stainless steels tubulars. Corrosion tests were carried out at temperatures between 70 to 130°C. The stimulation acid/scale dissolver packages consisted of 10%HCl, 15%HCl, and %HCl plus 1%HF including corrosion inhibitors and inhibitor intensifiers. The range of applicability and compatibility against the tested alloys was defined.
