The increased use of corrosion resistant alloys (CRAs) in deep HPHT wells has led to production-tubing cracking failures throughout the industry. Many of these failures have occurred from the outside (annulus side) and been attributed to Environmentally Assisted Cracking (EAC) and hence, best described as Annular EAC (AEAC). Examination of these failures points to a serious incompatibility of the production tubing metallurgy with the packer fluid under stress.

To solve this problem, combined expertise in fluid chemistry and metallurgy is needed. Consequently, in 2003 a research alliance of the co-authors to examine the compatibility of a wide spectrum of completion fluids with various martensitic stainless steel metallurgies was established.

This unique research collaboration leading to extensive stress cracking testing performed with different metallurgies and different fluids under simulated well conditions has resulted in an extensive database and new body of knowledge regarding the causes behind AEAC failures. With respect to the mechanisms of failure, a variety of contaminants in completion/packer fluids have been found to play a dominant role. Such contaminants include sulfur-containing species, oxidants, and select ionic species. This paper addresses the impact of the new information and identifies serious misconceptions regarding the role of completion & packer fluids in the tubular failures.

The information accrued from this comprehensive study has advanced the industry's knowledge of the causes of AEAC by detailing the previously unrecognized importance of various contaminants present in the fluids. Importantly, it has led to the recognition of the need for quality assurance and best-practice fluid management throughout the life cycle of the fluids. The extensive database and a user friendly software program derived from it permit minimization of tubular failure risk by matching packer fluids with metallurgies under a wide variety of stipulated well conditions.

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