When ENI embarked on Congo’s LNG project, they entrusted Ocean Installer with a challenge, find a safe, efficient and successful method for the world’s first two vessel combined offshore FLNG system installation!

Our mission was to find a safe and operationally robust solution to execute something that had never been done offshore before – the solution, an innovative combined tow of the FSU and FLNG. The engineering feats that were achieved during this project have set new standards for the industry, truly demonstrating Ocean Installer’s ability to innovate, collaborate, and deliver complex, high-risk solutions within tight timelines.

The ENI Congo LNG project presented a variety of engineering hurdles from the outset. Most notably, how to safely moor Floating Storage Unit (FSU) and Floating Liquefied Natural Gas (FLNG) unit offshore in a split mooring spread.

This resulted it the world’s first offshore combined tow of a Floating Storage Unit (FSU) and Floating Liquefied Natural Gas (FLNG) unit. The goal was to moor these two massive vessels at a nearshore site, using a split mooring system that had never been applied offshore before.

As the Project Manager, Matteo Mosca recalls, “The immediate challenge was adapting a harbor-based FLNG terminal to a nearshore environment. This required extensive analysis to simulate the behavior of the two floaters, ensuring they would remain safely moored without collision during station-keeping operations.”

The project’s timeline also added pressure. Starting as a FEED (Front-End Engineering Design) study, the project progressed to execution in under a year.

“A lot of the challenge came from the timeline,” explains Iarla Lewis, Global Technology Director at Ocean Installer. “It didn’t allow the normal flow of a project yet, the team’s ability to adapt to these extreme conditions was truly remarkable.”

Moreover, the environmental conditions of the Congo coastline, along with the complexity of the operation, made it clear that the success of the project would depend on both the execution of innovative engineering and the ability to coordinate and manage a multitude of external contractors and partners.

According to Syed Uddin, Project Technical Manager, “The combined tow was a highly innovative technique. We used simulations to model the two vessels as a 3-body arrangement, which helped us understand how the vessels would interact and where the potential risks were.”

With our project and operational team in charge of the planning of all operational simulations and scenarios for the project, Kongsberg Maritime’s facilitation played a pivotal role in the project’s success.

Thus the operational team got to train on the exact parameters of the tow using advanced simulation models. That enabled them to practice and anticipate challenges, such as the risk of heading restrictions and the complex interactions between the vessels. All those things that they would see in real life operation whilst off the project critical path.

This level of preparation meant that by the time the vessels were in open water, every team member was well-versed in the potential challenges and knew how to handle them.

“The training was invaluable,” Syed recalls. “We had to ensure that all parties, from Ocean Installer to the subcontractors and even the pilots, were familiar with the operational restrictions and how they would affect the tow. The collaboration between Ocean Installer and Kongsberg was crucial to this.”

Despite the meticulous planning and simulations, unexpected challenges arose as the project unfolded. The initial plan called for the offshore connection of the hawsers between the two units. However, during the course of the project, it became clear that this approach was not feasible due to equipment limitations on board and the risk to our personnel.

This necessitated a change in strategy: in-shore hawser connection followed by a combined tow.

The in-shore connection method, in which the hawsers were connected while still in port, eliminated the direct risk to personnel in open water. This was particularly important, as it reduced the potential for accidents during the critical phase of mooring the two vessels together. In total, the team had to install 20 nylon hawsers to ensure that the vessels were securely moored.

According to Matteo Mosca, the decision to move the connection inshore was a pivotal moment: “Safety was always our primary concern. The risks associated with offshore hawser connection in a nearshore environment were far too great. The decision to change the approach was the right one, and it worked perfectly.”

A major factor in the success of the ENI Congo LNG project was the strong sense of collaboration among all parties involved. From Ocean Installer’s internal teams to subcontractors and external partners, communication and coordination were paramount. Iarla Lewis emphasizes the importance of this collaboration, saying, “The key to this project was coordination and communication. Syed and Matteo did an excellent job of ensuring that OI, subcontractors, the client, and third parties were all aligned with the plan.”

The project’s success also owes much to the exceptional performance of the subcontractors, who brought their specialized knowledge and skills to the table. Partners like BV, Sealand Projects, Houlder, and Global Maritime played critical roles in performing simulations, analyzing towing dynamics, and conducting hydrodynamic studies of the spacer frames.

“Sealand ran the base case offshore execution analysis, while Global Maritime performed the combined tow analysis,” Iarla adds. “At the same time, Houlder ran hydrodynamic analysis of the spacer frame and its interaction with the vessels, ensuring every part of the operation was fully tested.”

As Syed Uddin puts it, “One of the most rewarding aspects of this project was how the team came together. We had subcontractors who seamlessly integrated with Ocean Installer, to the point where it didn’t feel like they were external. The sense of unity was extraordinary.”

The ENI Congo LNG project is a testament to Ocean Installer’s expertise in offshore engineering, its commitment to safety, and its ability to turn ambitious ideas into reality.

With a team of dedicated professionals, cutting-edge technology, and a collaborative spirit, Ocean Installer not only met the challenges of this project but set a new standard for the industry in the process.