Intervention and Completion Landing String Qualification for HPHT Application

To optimize offshore intervention and completions operations, drill pipe-based riser (DPBR) designs with proprietary gas-tight, rotary-shouldered connections are being evaluated as alternatives to traditionally used casing products. This paper describes the design and development process of a DPBR including material qualification and connector qualification, which was pieced together from various applicable industry codes, such as National Association of Corrosion Engineers (NACE) MR0175, NACE TM0177, American Petroleum Institute (API) 17G, API Spec 5DP, API TR 17TR8, and ASME Boiler and Pressure Vessel Code Section IX. Wherever applicable, the more challenging and stringent requirements were chosen. Material selection and qualification were performed to meet the NACE MR0175 requirements for Region 2. Sulfide stress cracking tests were performed on all base materials and friction welds in accordance with ANSI/NACE MR0175andNACE TM0177. Sub-scale fatigue testing was performed to determine the environmental knockdown factor and used to determine the fatigue capacity of the DPBR in the expected fluid/environmental conditions. Finite-element analysis was used to determine the worst-case design configurations. These results were then used in full-scale physical testing with nine samples. Validation of the connector capacities was performed by make-and-break (endurance) testing, sealability testing, and cyclic (fatigue) testing with internal pressure. Limit-load testing was performed to validate the static load capacity of the connector. A qualification bridging was performed comparing the results from FEA and physical testing. An independent third party witnessed and reviewed all relevant design and qualification activities per the Bureau of Safety and Environmental Enforcement requirements for high-pressure high-temperature equipment.