The challenging nature of high pressure high temperature (HPHT) oil and gas production wells has necessitated the development of new technologies and the use of high performance materials and fluids. Inevitably, this has resulted in some unexpected phenomena and field failures have been responsible for stimulating research into several aspects of corrosion and environmental cracking associated with HPHT production.

This paper details the investigation of production tubing coupling failures, which occurred during the retrieval of cold worked 25Cr duplex stainless steel production tubing. The tubing had been present in a suspended well for two years and was being retrieved as part of a workover operation. The investigation was conducted to determine the nature of the failures and identify contributory factors and has resulted in recommendations for long term use of formate brines at high temperature.

Keywords:
HPHT, high pressure high temperature, oilfield chemistry, complex reservoir, Brine, correlation, investigation, Qualification Testing, Completion Installation and Operations, Discolouration
Subjects:
Production Chemistry, Metallurgy and Biology, Unconventional and Complex Reservoirs, HP/HT reservoirs, Completion Installation and Operations, Corrosion inhibition and management (including H2S and CO2)
Copyright 2009, Society of Petroleum Engineers
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