Overview

Extreme offshore hydrocarbon operations require strong, durable, and corrosion resistant materials. Metallic components are used in risers, umbilicals, drill pipe, pipelines, blow out preventers, and numerous other components associated with offshore drilling in both the water column and subsurface systems. Ensuring the lasting performance and the appropriate use of these materials is a vital step in addressing the economic, environmental, and safety concerns related to efficient offshore production and risk prevention. Unfortunately, materials used in offshore oil and natural gas operations have reached their limit of effectiveness in terms of operating environment. New materials must be designed.

This project evaluated the most commonly used alloys in these applications to characterize their limitations and appropriate uses. The project also identified environmental and mechanical factors that affect metal performance in extreme offshore environments.

The development of material information databases to catalog and analyze baseline physical and mechanical behavior, as well as environment specific property performance of basic materials, was an important element of this project. This work reduced the relative risks for critical components in offshore environments by using data analytics and other large data strategies to determine expected materials lifespan under different operating scenarios. A Technical Report Series publication presents findings on Fatigue Crack Growth Rate of UD-165 in Sour Environments.

Approach

This project seeks to identify the failure mechanisms and rates of material degradation for critical components in offshore drilling by basing determinations on observed/reported behavior in the field. However, as there is limited publicly available data on the performance of these materials under extreme offshore conditions, the study will be augmented with experimental research on materials performance under simulated extreme conditions. To date, this study has successfully evaluated the strength/corrosion potential of the most common alloys used in extreme offshore drilling under in situ conditions (pressure, temperature, hydrogen sulfide, etc.). Work is ongoing in the development of a pit/fatigue model for the assessment of catastrophic failure potential of these metallic components. NETL is also evaluating new alloys (e.g., nickel-based alloys as a structural material or as a cladding onto steel) and surface treatments (e.g., hammer peening) for ultra-deep well environments. A recent Technical Report Series publication presents findings on Fatigue Crack Growth Rate of UD-165 in Sour Environments.

Outcomes

This project identified the failure mechanisms and rates of material degradation for critical components in offshore drilling by using observed/reported behavior. The research successfully evaluated the strength/corrosion potential of the most common alloys used in extreme offshore drilling under in-situ conditions. The researchers also evaluated new alloys and surface treatments for ultra-deep well environments.

The primary outcome of this project was the knowledge gained of the environmental and mechanical factors that affect metal performance. Other key outcomes included:

• An understanding of the fatigue behavior of high-strength steels for the next generation of ultra-deepwater risers.
• Knowledge about how modifying the surface high-strength steel and nickel superalloys improves the corrosion and fatigue performance components, especially for application in failure-prone component locations.
• Data on the effect of environmental factors and the impact of localized corrosion on fatigue crack initiation and propagation in drill string alloys.
• Understanding of the corrosion behavior of alloys in simulated sour service environments as functions of pH, temperature, and hydrogen sulfide concentration, and determining the role of hydrogen sulfide as a catalyst on the corrosion degradation process.
• Reference electrodes for use in high pressure/high temperature systems for corrosion sensors for down-hole application.

The fatigue crack growth rate and fracture toughness of ultra-high strength steel (UD-165) and several nickel superalloys (IN 718, IN 625, IN 725) were determined under offshore, deep-well environmental conditions. The effect of surface modification (e.g., hammer peening) were investigated for IN 718 for aggressive environmental conditions.

Research Products

Explore research products that are related to this project.

Contacts