Trelleborg and McDermott Successful Partnership
Completing a two and a half-year project, Trelleborg and McDermott Australia Pty Ltd team up to ensure safe and efficient installation of a newly constructed Floating Production Unit’s hull in Woodside’s Scarborough gas field, based in the Carnarvon Basin off the coast of Western Australia.
1. What were the main technical challenges in designing the Leg Mating Unit (LMU) with the sandcan system and implementing this solution for a 30,000MT topside?
The LMU and sandcan system must control the settlement of the topside as it transfers its full weight onto the semisub structure. Abrupt or uneven settlement can overload certain parts of the semisub or lead to local failures. Installing a massive structure like a 30,000MT topside involves dealing with weather windows, offshore installation vessel limitations, and variable sea states. High precision is needed under less-than-ideal conditions. The sandcan system, often filled with materials like sand, helps to control the final settling process by acting as a buffer during the weight transfer. The challenge is ensuring that the material within the sandcan behaves predictably under load, which requires careful design and testing.
2. How did you approach the sand selection process for the sandcan system, and why was this aspect so critical to the project's success?
The sand selection process for the sandcan system is a crucial step in ensuring the success of the Leg Mating Unit (LMU) and the overall stability of the topside during installation. This process directly impacts the load transfer, settlement behavior, and long-term performance of the system.
The grain size distribution (gradation) is one of the most important factors in selecting sand for the sandcan system. Sands with a well-graded particle size distribution (a good mix of different-sized grains) offer better compaction and load-bearing capacity compared to uniformly graded sands. Well-graded sand reduces the risk of excessive settlement or movement during load transfer. It helps distribute forces evenly across the sandcan, ensuring smooth and controlled settlement.
Sand with high strength and excellent compaction properties is selected to handle the significant loads imposed by a 30,000MT topside. Laboratory tests, such as Proctor compaction tests, are often conducted to understand how the sand behaves under load and how much it can compress before it becomes dense enough to resist further settlement. Properly compacted sand resists excessive settlement, providing a stable and predictable base for the topside. Inadequate compaction could lead to uneven settling, which can cause differential movement between the topside and semisub, risking structural integrity.
3. How significant is it to conduct a full-scale testing of the LMU? Could you describe a bit about the testing capabilities at Trelleborg’s Singapore facility?
Conducting full-scale testing of the Leg Mating Unit (LMU) is of critical significance for ensuring the system's reliability and performance, especially for large offshore installations like a 30,000MT topside.
Full-scale testing helps validate design assumptions, verify the LMU’s behavior under real-world conditions and identify potential issues before deployment.
Trelleborg’s Singapore facility is one of the key centers for testing and developing LMU and similar offshore engineering systems. The facility offers comprehensive testing capabilities, including full-scale static load testing, creep, stress relaxation and fatigue testing.
4. In what ways do you think the success of this project will influence future floatover installations in the offshore energy sector?
The success of this project—particularly in the development and implementation of the Leg Mating Unit (LMU) with the sandcan system for a 30,000MT topside—could have a significant influence on future floatover installations in the offshore energy sector. The proven success of advanced LMU designs with sandcan systems will set a new standard for offshore floatover installations. If these technologies demonstrate superior load absorption, smoother mating processes, and enhanced structural integrity, they will likely become the preferred option for future projects. More offshore developers may choose to incorporate LMUs with enhanced damping systems, leading to better load management during topside installation. The sandcan technology, if it proves effective, may also become a critical part of future floatover designs, improving the precision and control of the settlement process.
Oil and gas platforms and offshore wind substations are getting larger due to increased demand and technological advancements. The success of this project could position the floatover method as a viable, cost-effective alternative to traditional heavy-lift crane operations, encouraging more widespread adoption for larger topsides.
5. Can you walk us through the process of using Finite Element Analysis and adhering to API RP WSD guidelines in your design approach?
Using FEA in conjunction with API RP WSD guidelines ensures that the design of the LMU and sandcan system is both structurally robust and compliant with industry standards. The FEA provides detailed insight into how the structure will perform under various loads, while the API guidelines ensure safety through built-in factors and specific design checks. Together, they form a comprehensive approach to ensuring the LMU and the overall offshore structure can withstand the harsh environmental and operational conditions offshore.
6. How did you balance the need for a system capable of withstanding 7,500 metric tons of load with considerations for weight, cost-effectiveness, and manufacturability?
Balancing the need for a system capable of withstanding a massive 7,500 metric tons of load with considerations for weight, cost-effectiveness, and manufacturability is a complex engineering challenge. This balance is crucial to ensure the structural integrity of the Leg Mating Unit (LMU) while keeping the project feasible from both economic and production standpoints. Balancing load capacity with weight, cost-effectiveness, and manufacturability involves optimizing materials, refining the design through FEA, and focusing on simplified manufacturing techniques. By leveraging advanced materials, modular designs, and collaboration between engineers, the system is designed to handle 7,500 metric tons safely while keeping production and installation practical and cost-efficient.
7. Recent reports suggest a growing trend towards floating production units in offshore oil and gas. How does Trelleborg's LMU technology align with this industry direction?
Trelleborg’s Leg Mating Unit (LMU) technology aligns well with the growing trend toward floating production units (FPUs) in the offshore oil and gas sector, as the industry increasingly shifts towards deeper waters and harsher environments where floating solutions are essential.
The LMU’s capabilities in energy absorption, load management and reliability in harsh environments make it a strong fit for the dynamic conditions faced by FPUs. As the industry moves toward deeper waters, larger structures, and more complex installation environments, Trelleborg’s LMU systems can provide critical support in ensuring safe and efficient operations for floating platforms.
Trelleborg’s LMUs have a solid history of successful implementations in large-scale offshore projects, providing confidence to operators considering new floating platforms. This established success in challenging environments positions Trelleborg’s technology as a reliable solution for future FPUs, where risk mitigation is essential.
8. Based on your experience with the Scarborough project, what future innovations or improvements do you foresee in float over installation technology?
Based on the experience with the Scarborough project, several future innovations, and improvements in floatover installation technology can be anticipated, driven by the increasing complexity of offshore installations and evolving industry needs. These innovations aim to enhance safety, efficiency, cost-effectiveness, and environmental performance. The experience with the Scarborough project points to a future of floatover installation technology that is more automated, precise, and resilient. Improvements in load management, motion compensation, sustainability, and digital twin technology will enhance the efficiency and safety of installations. The growing emphasis on real-time monitoring will further streamline operations and reduce risks, allowing for faster, safer installations in deeper waters and more challenging environments. These innovations will position floatover technology as a key enabler for the next generation of offshore oil and gas projects.