Complexity reduced in floating production storage and offloading vessels

Floating production storage and offloading (FPSO) vessels deliver the same functionality as stationary oil & gas platforms while being able to relocate as economic headwinds or drilling opportunities change. As such, they have emerged as an efficient, economical way to take advantage of oil fields across the globe.

The industry anticipates FPSO deployments rising significantly over the next five years. Some forecasts expect growth in excess of 14% by 2027. For these vessels to be successful, a few key considerations impact the construction process, particularly regarding critical fluid system applications and packages. In this article, we examine some of the complexities of commissioning these systems throughout the construction process.

Challenges, considerations

When commissioning an FPSO, owner/operators practice the same due diligence as for conventional offshore platforms, but the nature of FPSOs brings unique challenges to light. For example, it is essential to maintain tight and efficient construction schedules to ensure that constructing an FPSO remains a more economically advantageous solution than if the operator had simply constructed a fixed platform instead.

FPSOs are expected to deliver more than 20 years of uninterrupted service, as maintenance-related dry dockings can sink any potential cost efficiencies. On-board fluid systems must deliver reliable and safe performance throughout this time period. Finally, strict adherence to industry compliance standards is mandatory. As the oil & gas industry seeks to minimize its environmental impact, FPSOs will operate with the goal of achieving net-zero in the future.

Owner/operators coordinate with several global entities. Whether an operator is retrofitting an existing hull or starting from scratch, most hulls are supplied or built within the Asia-Pacific region (See figure 1) for coordination, shipment, and delivery of the hull to the location where the necessary fluid systems will be integrated and commissioned.

Today’s topside applications and packages are increasingly specialized. Major capital projects, FPSOs included, commonly involve numerous engineering, procurement, and construction (EPC) firms from different global regions. EPCs are responsible for equipment for several critical packages, and successful coordination with each of them is essential throughout the pre-front-end engineering and design (pre-FEED) project stage. Depending on the owner/operator’s available resources, this can be a challenge.

Figure 1: FPSOs contain numerous critical fluid system applications and packages, each of which must deliver long-term reliability across the vessel’s life. Courtesy: Swagelok

No one-size-fits-all solution for applications and packages found on an FPSO exists. Designers must think critically about priorities, including reservoir characteristics; FPSO motion while at sea; hull size and storage capacity; type of export system; single or twin production trains; and potential redeployment and decommissioning.

A supplier who has an established, local presence in the many different regions where resources reside can be a boon for the project. People who understand local cultures, languages, and regulations can be a significant benefit.

Taking stock of critical systems

Owner/operators must ensure all onboard systems operate reliably once an FPSO has been deployed. Safety of the crew depends upon it.

Applications on an FPSO essential to safe, efficient and productive vessel operation include:

Process and analytical instrumentation. It is not always a guarantee that the right expertise will be readily available at a project’s outset to make the right product, material, and design choices for efficient and effective analytical systems. As such, overall system design can pose an early challenge. Poor installation practices during hookup and commissioning can additionally lead to longer project lead times or may result in leakage, emissions, and safety concerns. For these reasons, it can be beneficial to consult with your fluid systems providers to overcome these challenges.

Rotating equipment (Figure 2). Pumps, compressors, and turbines are essential to an FPSO’s overall reliability. If any of these systems malfunction, the resulting downtime can lead to costly shutdowns. Dependable mechanical seal support systems—which keep seal fluid clean and deliver fluids at the right pressure and temperature—can contribute to higher reliability, helping to keep these critical units running effectively.

Figure 2: Rotating equipment, including pumps, compressors, and turbines, are critical to overall operational reliability. Downtime can lead to production shutdowns and profit losses. Courtesy: Swagelok

Turret swivel systems (Figure 3). These systems connect an FPSO’s topside and subsea systems, commonly using long hose lengths to make such connections. However, hoses require frequent maintenance inspections and may only provide a few years of service depending on environmental and operational conditions. Hose-related production losses can lead to millions in costs. Instead, turret swivel systems can be designed with permanently installed tube and only short jumper hoses for flexibility. These kinds of systems have been shown to decrease maintenance requirements and improve overall reliability.

Figure 3: A turret swivel system provides crucial connection points between topside and subsea systems. A well-designed installation using permanently installed tube can offer a more reliable and lower maintenance solution. Courtesy: Swagelok

Sampling systems (Figure 4). Many different sampling processes are required on a typical FPSO. However, it is not uncommon for these sampling points to be inconsistent, system-to-system. This kind of inconsistency, both in system design and operability, can lead to compromised sampling accuracy. Instead, owners/operators can specify properly-designed and intuitive-to-use sampling systems across the entire vessel, helping operators maintain chain of custody, compliance, and proper process control.

Figure 4: Sampling systems must be properly designed to deliver representative samples and allow operators to safely use the system, maintain chain of custody compliance, and make proper process control decisions. Courtesy: Swagelok

Chemical Injection (CI) units (Figure 5). CI units must deliver highly accurate and repeated chemical doses into production—any lapses in this process can compromise reliable production. A typical CI system may require hundreds of individual connections. As such, leak-tight performance is a necessity to maintain safety and protect the environment. Downtime can result in significant losses.

Figure 5: CI units must maintain highly accurate and repeatable chemical dosage into the production process to provide reliable production. Leak-tight performance is essential. Courtesy: Swagelok

For these applications, in which leak-tight connections are so critical, it can be beneficial to specify fluid system components from a single, reliable supplier. Tubes, fittings, and valves that are explicitly designed to deliver leak-tightness can make a significant impact on the vessel’s long-term performance. Alloy choice is also a consideration here—higher-quality materials that can provide outstanding corrosion resistance can be beneficial in the harsh conditions where FPSOs operate.

Supplier selection

In single-sourcing critical fluid system parts, it is worth ascertaining what other forms of support a supplier offers. For example, a supplier with a full breadth of individual components, prefabricated assemblies, project management assistance and global reach can further support FPSO construction. Your supplier may also be able to assist with specifications, recommend efficiencies, and help identify cost-saving opportunities. As the project proceeds, a supplier should also help manage timelines and logistical complexities. And if a supplier can help maintain job site inventory and product availability throughout construction, it increases the chances of realizing on-time, on-budget project completions.

Original content can be found at Oil and Gas Engineering.

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