The offshore production of hydrocarbons is moving into deeper and more remote locations. FPSOs (Floating Production, Storage, and Offloading vessels) are proving essential for cost-effective oil production, storage, and offloading. They operate as floating factories outfitted with tools, thus supporting the processing of crude oil and gas from underwater wells while ensuring safety and compliance with standards. They are vital components of the offshore oil and gas sector.

In this piece, we’ll look at the function of FPSOs in oil and gas: how they work, why they’re useful, the design challenges they face, and how Rishabh Engineering can assist using real-world examples.

FPSOs are sea-based floating vessels for oil production, storage, and offloading. They permit the processing and storage of oil and gas. FPSOs are widely utilized in the offshore industry as a principal oil and gas production, processing, and storage technique. Oil and gas corporations typically lease them. The boats contain diverse processing equipment that aids in the separation, storage, and offloading of crude oil and gas collected from subsea oil wells or platforms. After processing the oil and gas, FPSOs store it safely before offloading it into a tanker or transporting it via pipeline.

FPSOs are meant to gather hydrocarbons produced by themselves or from nearby platforms or subsea templates, process them, and store oil until it can be offloaded onto a tanker or, less commonly, supplied via a pipeline. They are suited for a wide range of water depths and environmental conditions and can be constructed to operate for at least 20 years.

FPSOs are used in the following situations:

• Marginal fields: Fields with a reserve of 15 to 20 years
• Remote wells: Wells that are far from onshore facilities.
• High-cost onshore facilities: While constructing onshore facilities is expensive, FPSOs are cost-effective units since operators move into deeper waters.

The main parts of FPSO include:

• Hull: It is the top of the ship above sea level, and it is either newly built or made from the conversion of existing tankers. Often, hulls are designed to match project-specific conditions, which can vary greatly depending on the regions in which it will operate.
• Mooring System: This equipment ensures that the FPSO safely stays in place despite whatever natural forces, waves, winds, and currents it faces. It comprises of mooring lines, anchors, and connectors.
• Topside: It is the gas processing unit for the FPSO at the top of the vessel, and it is designed & constructed for specific offshore platforms while adhering to refinery standard specifications (API & ASME).
• Risers: This component allows the vessel to move vertically and laterally. The flexible steel reinforced risers are designed to absorb any motion that affects the vessel’s position by waves.
• FPSO Turret: It is an integrated part of the FPSO hull. It helps the hull weathervane around the mooring system and the mooring line, allowing the FPSO to rotate freely while mooring to different seafloor locations. This is especially true for adverse weather conditions on the vessel. Furthermore, detachable turret systems allow the turret to be detached from the vessel while remaining linked to the seabed’s mooring lines. This is especially effective in situations like hurricanes and storms, where the vessel must respond swiftly to external risks.
• Gas, water, and oil separator: Water, gas, and oil have different densities, which implies that they can be split in a special separator. And, with gas rising to the top, water on the bottom, and oil staying in the middle.

FPSOs are classified into four types based on their processing & storage capabilities, as listed below;

• Floating, Storage, and Offloading (FSO) unit
• Floating, Drilling, Production, Storage, and Offloading (FDPSO) unit
• Floating, Production, Storage, and Offloading (FPSO) unit
• Floating, Storage, and Regasification Unit (FSRU)

• Cost-effective: FPSOs are less expensive than typical offshore oil and gas installations and offer more flexible leasing arrangements.
• Flexible: FPSOs can connect to any pipeline and be relocated if an oilfield is depleted. This saves time and money by removing the need to construct costly permanent pipelines and infrastructure.
• Safe: FPSOs are safer than conventional methods. They can also be unplugged from the pipelines and oil wells attached to them.
• Timesaving: FPSOs can be extremely effective in deep ocean and remote regions where seabed pipelines are not viable.
• Environmental considerations: Regarding environmental concerns, FPSOs provide major advantages.

• Construction time: FPSOs take around 1-2 years to build or convert and require a costly and timely environmental study for a specific field once accepted.
• Maintenance: FPSOs require careful maintenance and inspection to ensure their optimal performance.

Floating production storage and offloading (FPSO) installations have several design challenges, including:

• Environmental impact: FPSOs are designed to achieve net-zero environmental impact. However, conventional methods, such as gas turbines to generate electricity, can create emissions, and venting can release harmful gases.
• Space availability: This being a floating platform, every space available needs to be utilized optimally, still managing operation and maintenance ease.
• Demolition of existing process modules: Demolition of existing modules as needed based on the type of field and technology enhancement becomes very challenging.
• Installation and integration of new modules: Installation of new modules on the FPSO while at sea is very challenging as it involves careful design and activity sequencing.
• Technical challenges: FPSOs operate in harsh offshore environments and must meet strict safety and environmental regulations. Poorly designed compressors can cause unstable operation, low efficiency, and recycle valve freezing.
• Lack of standardization: Different FPSO projects may not be standardized, leading to challenges.
• Stakeholder management: FPSO projects usually involve multiple stakeholders, including project owners, engineering firms, construction contractors, and regulatory bodies.
• Budget and schedule risks: The time spent in the shipyard is dictated by how well the FPSO aligns with the next field’s requirements. For example, if the new field has an anticipated life of 20 years, but the FPSO has a remaining structural fatigue lifespan of 10 years, that’ll be an issue.
• Refurbishment: Refurbishment is required to enhance the working life of FPSO by extensive repair and modernizing existing process equipment. Integrating new technology into the existing one requires As-Built data, which is often missing.

Our team assists with FPSO design while addressing the challenges through their experience in engineering and design services. It involves using various standards, codes of practice, specifications, and national and international laws. FPSOs are designed and built according to sea conditions, production period, production volume, and installation requirements.

Here are some ways how our team can help;

• Structural Engineering: Structural engineers play a crucial role in designing the topsides of the FPSO while ensuring that the structure survives various environmental loads such as waves, wind, and currents. To ensure FPSO’s longer operational lifespan, our engineers’ consider factors like fatigue, corrosion, and structural integrity.
• Skid Engineering: We have vast experience conceptualizing and designing process modules/ modular skids to help address space and integration challenges.
• As-Built data capture: Our team can help capture As-Built data using Laser scan.
• Mechanical Engineering: Mechanical engineers design the machinery and equipment onboard the FPSO, including pumps, compressors, turbines, and mooring systems, while ensuring reliability, efficiency, and safety in the operation of FPSOs.
• Process Engineering: Process engineers optimize equipment and piping systems layout while designing the production and processing facilities on the FPSO to separate oil, gas, and water efficiently. This is while meeting production targets and adhering to safety and environmental regulations.
• Electrical Engineering: The electrical engineers design the electrical systems onboard the FPSO, including power generation, distribution, and control systems, thus ensuring a reliable power supply for related equipment & systems, and adhering to safety measures such as grounding and lightning protection.
• Instrumentation and Control Engineering: Instrumentation and control engineers design the automation and control systems to monitor and regulate various processes onboard the FPSO while implementing safety shutdown systems, control valves, and instrumentation to ensure safe and efficient operations.
• Safety Engineering: Safety engineers work to identify and mitigate potential hazards onboard the FPSO while conducting risk assessments, implementing safety procedures, and designing safety features to protect personnel and the environment.

Case 1: Metering Skid of FPSO Slug Catcher

Project: Detailed Engineering & 3D Modeling for Oil & Gas Metering Skid of FPSO Catcher

Client: Metering Skids Supplier

Objective: Rishabh Engineering executed detailed engineering for an Oil & Gas Metering Skid of FPSO Catcher, integrating CADWorx for a comprehensive 3D model. Our scope encompassed GA drawings, pipe stress analysis, structural steel calculations, piping, and structural fabrication drawings, and MTOs for all elements, including weight, COG, lifting, and monorail calculations, delivering a fully optimized solution meeting client specifications and regulatory standards.

Case 2: Laser Scan to 3D Modeling of Topside FPSO Module

Project: FPSO Topside Module Laser Scan To 3D Modeling

Client: A multinational energy corporation

Objective: Rishabh Engineering undertook a crucial project for a leading US-based multinational energy corporation, aiming to revolutionize the FPSO gas plant project in West Africa. By leveraging advanced laser scanning techniques, our multidisciplinary team helped with Laser Scan to 3D Modeling of the Topside FPSO Module by meticulously executing site surveys, collecting data, and generating dynamic 3D models across various disciplines, including piping, mechanical, civil, structural, electrical, and instrumentation. This comprehensive approach facilitated precise layout design, equipment positioning, and detailed reports, ensuring optimal functionality and efficiency for the FPSO topside module.

FPSO is essential in offshore oil & gas extraction as it offers flexibility, cost-effectiveness, and safety. They are important in oil & gas production while contributing significantly to the industry’s sustainability. As a multidisciplinary engineering services company, we at Rishabh Engineering are witnessing a global resurgence in FPSO projects in regions including West Africa, the Middle East, and Latin America. We are working with leading O&G companies & operators to support their FPSO development while ensuring safe and efficient production.

We can help design your FPSO modules to optimize performance to enable you to drive offshore oil & gas efficiency and sustainability.