Preventing Environmentally Induced Corrosion Cracking by Removal of Thiocyanates from Completion Brines

Horton, Robert; Arvie, Morris

doi:10.2118/110111-ms

“…• Even though the bulk of the field failures have occurred with CaCl 2 fluids, approximately 85 to 90% of these fluids have contained thiocyanate ion, a well-recognized strong contributor to AEAC based on stress corrosion testing (Robinson 2004;Kane et al 2005;Ke and Qu 2006;Horton and Arvie 2007).…”

Section: Resultsmentioning

confidence: 99%

Misconceptions Regarding the Chemical Role of Completion/Packer Fluids in Annular Environmentally Assisted Cracking of Martensitic Stainless Steel Tubing

McKennis

¹

,

Sook-Bae

²

,

Termine

³

et al. 2010

SPE Journal

0

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The increased use of corrosion resistant alloys (CRAs) in deep high-pressure/high-temperature (HP/HT) wells has led to production-tubing cracking failures throughout the industry. Many of these failures have occurred from the outside (annulus side) and have been attributed to environmentally assisted cracking (EAC) and, hence, are 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.In 2003, combining expertise in fluid chemistry and metallurgy, the authors formed a research alliance to address the AEAC problem by examining the compatibility of a wide spectrum of completion fluids with various martensitic stainless steel (MSS) metallurgies. This unique research collaboration, involving extensive stress-cracking testing performed with different metallurgies and different fluids under simulated well conditions, has resulted in an extensive database (more than 4,000 test entries for 27 fluids and six MSS metallurgies) and a new body of knowledge regarding the causes behind AEAC failures.Conventional wisdom holds that chloride ion and oxygen play major causative roles. The authors' findings, however, identify other contaminants in completion/packer fluids that play the dominant role in the chemical mechanism of the crack failures. Such contaminants include sulfur-containing species, oxidants other than oxygen, and select basic ionic species. This paper addresses the effect of the new information and identifies serious misconceptions regarding the role of completion /packer fluids in the tubular failures.The authors' 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. As a consequence, the need for quality assurance and bestpractice fluid management throughout the life cycle of the fluids is now recognized. Misconceptions with respect to the chemical mechanisms and causative factors of AEAC failures are discussed. Such information should expand the industry's AEAC knowledge base and minimize the risk of tubular failure.

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The Role of Packer Fluids in the Annular Environmentally Assisted Cracking of CRA Production Tubing

McKennis

¹

,

Termine

²

,

Bae

³

et al. 2008

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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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Chemistry and Mechanisms of Completion/Packer Fluids: Annular Environmentally Assisted Cracking (AEAC) of Martensitic Stainless Steel Tubing: Misconceptions Regarding the Chemical Role of Completion/Packer Fluids

McKennis

¹

,

Bae

²

,

Termine

³

et al. 2009

All Days

3

0

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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. In 2003, combining expertise in fluid chemistry and metallurgy, the authors formed a research alliance to address the AEAC problem by examining the compatibility of a wide spectrum of completion fluids with various martensitic stainless steel (MSS) metallurgies. This unique research collaboration involving extensive stress cracking testing performed with different metallurgies and different fluids under simulated well conditions has resulted in an extensive database (> 4000 test entries for 27 fluids and 6 MSS metallurgies) and new body of knowledge regarding the causes behind AEAC failures. Conventional wisdom holds that chloride ion and oxygen play major causative roles. The authors' findings, however, identify other contaminants in completion/packer fluids that play the dominant role in the chemical mechanism of the crack failures. Such contaminants include sulfur-containing species, oxidants other than oxygen, and select basic 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 authors' 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. As a consequence, the need for quality assurance and best-practice fluid management throughout the life cycle of the fluids is now recognized. Misconceptions with respect to the chemical mechanisms and causative factors of AEAC failures are discussed. Such information should expand the industry's AEAC knowledge base and minimize the risk of tubular failure. Introduction In the last 10 years a relatively large number of stress corrosion cracking or environmentally assisted cracking failures of martensitic and duplex stainless steel (MSS and DSS) production tubing has occurred during high pressure/ high temperature (HPHT) applications (e.g., Mowat 2001, Mack 2002, Ibrahim 2003). These failures have been predominantly attributed to the interaction of a sensitive metallurgy under stress with the corrosive environment on the annulus side of the production tubing. As a consequence, to distinguish this type of cracking from that occurring on the production side of the tubing, this cracking is referred to as annular environmentally assisted cracking (AEAC). The increased occurrence of this mode of cracking coincided with the increased use of corrosion resistant alloy (CRA) metallurgies such as MSS and DSS for production tubing. Although the application of CRA tubing mitigated the problems of general and localized corrosion with acidic production environments involving CO2 and H2S (Kimura 2006 b), it introduced a new and perplexing corrosion mode ? AEAC. The field failures were, and continue to be, often catastrophic due to the severity and rapidity of the cracking during the production phase, with failures sometimes occurring within days or weeks after the onset of production (Kane 2005).

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Preventing Environmentally Induced Corrosion Cracking by Removal of Thiocyanates from Completion Brines

Cited by 4 publications

References 12 publications

Misconceptions Regarding the Chemical Role of Completion/Packer Fluids in Annular Environmentally Assisted Cracking of Martensitic Stainless Steel Tubing

Misconceptions Regarding the Chemical Role of Completion/Packer Fluids in Annular Environmentally Assisted Cracking of Martensitic Stainless Steel Tubing

The Role of Packer Fluids in the Annular Environmentally Assisted Cracking of CRA Production Tubing

Chemistry and Mechanisms of Completion/Packer Fluids: Annular Environmentally Assisted Cracking (AEAC) of Martensitic Stainless Steel Tubing: Misconceptions Regarding the Chemical Role of Completion/Packer Fluids

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