Part 1 of 4 on Qualifying Casing Connections for Underground Hydrogen Storage
In part one of a four-part series on qualifying well casing connections for underground hydrogen storage, we will look at the well design challenges that need to be addressed through testing.
Well casing and connections are currently qualified for service in many oilfield applications. The well casing design is evaluated through an engineering assessment using advanced structural-mechanical models that are validated through both material and full-scale testing in a controlled laboratory setting.
The models and testing procedures used for oil and gas applications, and even those used for underground storage of natural gas, need to be modified to account for the unique aspects of underground storage of hydrogen in salt caverns, depleted hydrocarbon reservoirs and deep saline aquifers.
Challenges with Underground Hydrogen Storage
The challenges of underground hydrogen storage include:
- Utilizing wells drilled kilometers below
- Numerous pressure and temperature cycles of either pure or blended hydrogen at high partial pressure
- Hydrogen’s ability to permeate through steel, causing hydrogen-induced embrittlement and crack formation, especially at high-tensile stress locations such as thread roots in the well casing connection.
With these challenges in mind, representative test programs can be used to evaluate material suitability and casing threaded connection designs for underground storage. These evaluations should include continuous, pressurized exposure to both hydrogen and blended gas environments. The materials should also be subjected to service loads caused by pressure and temperature cycles that occur in underground hydrogen storage operations. In some cases, testing might require consideration of geotechnical loading due to salt creep in cavern wells or formation compaction in reservoir and aquifer storage wells.
C-FER Technologies has extensive experience in developing and conducting both fit-for-purpose and industry standard evaluation programs for casing connections, and full-scale sour service equipment testing. We have developed a complete and representative evaluation methodology including structural-mechanical modeling and full-scale testing for casing and connections intended for use in hydrogen storage wells.
In parts two to four of this series, we will look at:
- Why Small-scale Material Characterization Tests in Hydrogen are Needed for Underground Hydrogen Storage
- The Importance of Specimen Selection and Preparation for Underground Hydrogen Storage
- Special Considerations in Conducting Full-scale Structural and Sealability Testing for Underground Hydrogen Storage
