Introduction to fixed offshore platforms – an Aquaterra Energy guide

Estimated read time: 9mins

Blog summary:

Fixed offshore platforms are moving with the tides of the evolving offshore energy industry. Historically, these structures have been primarily used to support the extraction of oil and gas from the seabed, but they now also play a pivotal role in enabling the production of essential offshore renewable resources. This guide delves into the history of offshore platforms, their uses and innovative designs – including our very own Sea Swift platform.

A history of offshore platforms

An offshore platform is a tremendous feat of engineering developed from over 100 years of industry expertise. As early as 1869, 10 years after America’s first commercial oil discovery in Titusville, Pennsylvania, one of the first patents for an offshore drilling rig was granted to T.F. Rowland. Although the Rowland offshore rig was designed to operate in water no deeper than 50 ft, its anchored, four-legged tower resembled early modern platforms. In 1937, a revolution was made – showcasing that offshore exploration and production could be highly lucrative. Built from wood, the  operated in only 14ft of water and was erected less than a mile from dry land but its mere existence set a record for both platform size and water depth for the Gulf at the time. The operation was named the Creole field and it continued to produce for more than 30 years, yielding nearly 4 MMbbl of oil.

Fixed offshore platforms today

A fixed offshore platform as the name suggests is a structure used to extract oil and/or gas , they are “fixed” to the seabed by various means, depending on water depth and other environmental factors. Today, this pioneering engineering has moved far beyond the wooden structures mentioned above. Over the decades, the technology has advanced significantly. This has allowed for the  development of much larger and more complex structures, capable of operating in water depths of 500 ft. They play a crucial role in the global energy industry and now, through merging new technologies, platforms can serve as offshore wind substations to transmit power to onshore grids. Moreover, they can also incorporate electrolysis technology for green hydrogen production.

Types of platforms and design

Offshore platforms come in a variety of shapes and sizes, each tailored to specific purposes and environmental conditions. At Aquaterra Energy we support a range of projects across the offshore energy sector through delivering innovative platform solutions that can be matched with different subsea structures and topsides like the designs mentioned below.

Monopiles:

Mainly used in shallow water, the design is composed of a large, single, tubular steel structure with its diameter varying depending on the requirements of the project. Their simplicity, coupled with the ability to sustain heavy loads, makes them a preferred choice for many energy projects, particularly in offshore wind, where they offer a reliable and relatively straightforward solution for anchoring turbines to the seabed. The simpler design also provides extensive cost and efficiency benefits to project owners.

Conductor Supported Platforms (CSP):

Are primarily used in shallow water environments, often in fields where the reservoirs are relatively small or in marginal fields where larger platforms are not economically viable due to fabrication or installation costs. These structures are generally less expensive to construct and install than larger offshore platforms and can be deployed relatively quickly, making them suitable for fast-track projects. Due to their size and efficient installation they can also provide a reduced environmental footprint in comparison to their larger counterparts. There’s also great potential for adapting CSP concepts for use in the renewable energy sector, particularly for smaller offshore wind or tidal energy installations.

Jackets:

Going into deeper waters or for heavier topsides, alternative foundation types like jackets or floating foundations are more suitable than monopiles or CPS structures. Jackets are typically made of a lattice framework of steel pipes or concrete and are named for their resemblance to a jacket-like construction around the legs and bracing. Primarily used for extracting oil and gas from beneath the seabed, they house drilling rigs, crew quarters, production facilities, and other necessary equipment. Through engineering innovation, jackets are now being deployed for both oil and gas and renewable offshore projects.

Sea Swift platform:

Embodying our commitment to intelligent design, this next-generation platform is modular and flexible which means it can be adapted to meet any number of field development needs. It has a wide range of benefits, making it the perfect solution for oil and gas, offshore carbon capture and storage, offshore wind, and offshore green hydrogen developments.

Not only that but it’s versatile:

• Subsea structures and topsides (such as those mentioned above) can be mixed and matched to specific field development requirements.
• The end-to-end simplified design, reduced steel requirement and focus on using in-country logistics and fabrication facilities keeps expenditure low and helps control project costs.

Sea Swift platform by Aquaterra Energy

Evolving engineering – meeting the needs of a transitioning sector

The energy sector is changing and that’s why our engineering at Aquaterra Energy has always been forward-looking. This means supporting operators who are committed to lowering their carbon footprint by rethinking designs such as replacing diesel gensets on topsides with solar panels or a wind turbine.

For example, we engineered a 100% renewably self-powered platform in Trinidad & Tobago, eliminating the need for traditional diesel generators or cables connecting to the grid. Its streamlined design used approximately 30% less steel than conventional jacketed foundations, eliminating the need for larger installation vessels and reducing reliance on steel. The project’s modular design meant it could be transported in prefabricated parts and assembled on-site, like industrial-scale Lego, without the need to bring in bigger vessels outside the country. The localisation and decarbonisation of the project meant the operator reaped both cost and carbon efficiency benefits.

Zandolie project – Sea Swift platform by Aquaterra Energy

Similarly, we applied this approach for a project offshore of Angola, where we designed a 100% autonomously powered platform for a major operator. Our engineers selected a power system using PV panels with battery storage for back-up power and calculated the optimal number of panels that would be needed for 100% autonomous power. This was combined with power-saving measures, such as the use of LED lighting, and resulted in a platform that was not only more efficient and environmentally friendly but also tailored to the specific needs of the client.

But it’s not just design that requires innovative engineering. Accurate monitoring of these structures is pivotal for success in harsh offshore environments. We provide the industry with essential digital monitoring – delivering real-time wave, motion, and current data for increased operational windows, reduced fatigue and improved overall project efficiency.

As we see the energy mix widening offshore, innovative engineering is, and will remain, a crucial aspect of enabling project viability and supporting the sector in reaching transition goals. This forward thinking is in our DNA at Aquaterra Energy and our expert engineers and analysts will continue to deliver the solutions needed for today and in the future.

Want to know how we can support your project? Get in touch.

Key takeaways:

In this piece we have answered:

What is an offshore platform?

An offshore platform is a tremendous feat of engineering developed from over 80 years of industry expertise. Historically these structures have been primarily used to support the extraction of oil and gas from the seabed, but they now also play a pivotal role in enabling the production of essential offshore renewable resources.

What is a fixed offshore platform?

A fixed offshore platform is a large structure used to extract oil and gas from beneath the seabed. These platforms are “fixed” to the seabed by various means, depending on water depth and other environmental factors.

What types of offshore platforms are used in the energy industry today?

Offshore platforms come in a variety of shapes and sizes, each tailored to specific purposes and environmental conditions. Some common structures include CPS, Jacket and Monopile platforms.

How have offshore platforms evolved with time?

Offshore platform technology has advanced significantly, allowing for the development of much larger and more complex structures capable of operating in a wide range of water depths from shallow to ultra-deep waters of over 10,000 ft. They play a crucial role in the global energy industry and now through merging new technologies, platforms can serve as offshore wind substation substations to transmit power to onshore grids and can also incorporate electrolysis technology for green hydrogen production.

External resources:

Chandrasekaran, S., Nagavinothini, R. (2020). Offshore Compliant Platforms: Analysis, Design, and Experimental Studies. United Kingdom: Wiley. Recovered from: Link

J K Paik, R E Melchers. (2008). Condition Assessment of Aged Structures. Woodhead Publishing Limited. Recovered from: Link

PDH Online. (n.d.). Course M550 content preview [PDF document].