Building floating wind installation and O&M strategies on oil and gas experience

November 14, 2023, posted by Admir Cavalic

Floating assets have long been installed, operated and maintained to support oil and gas (O&G) production. The emerging floating wind sector has specific challenges to overcome, but also opportunities to build strategies informed by O&G experience.

Opportunities and challenges
The global offshore floating wind market is expected to soar from 60 MW to more than 25 GW by the mid-2030s, with some forecasts anticipating 260 GW by 2050. However, operators face installation, and operations and maintenance (O&M) challenges relating to complexity, equipment size and distance from shore. While some of these challenges are unique to the sector, there is an opportunity for floating wind developers to build installation and O&M strategies that are informed by O&G experience.

Increased and larger mooring equipment
As floating wind units transition from 2-MW prototypes to arrays of 1 GW or more, the mooring industry must scale up supply chain capability to meet demand. The industry has a long history of mooring mobile offshore drilling units (MODU) and floating production, storage and offloading (FPSO) vessels, experience which can be exploited for floating wind. However, there are additional challenges for floating wind. For example, a typical MODU has eight mooring lines and anchors compared with three for a floating wind turbine, but a complete floating wind farm may require 200 or more. That is a huge increase in the volume of chain that will be needed, on top of existing demand.

In addition to a step change in chain volume, there is also the logistical challenge of handling larger diameter chains. For instance, some floating wind turbine designs specify 220mm diameters. While the O&G sector has experience handling large chains for the permanent mooring of some FPSO vessels, working with such large chains is rare. More typical diameters are 76 or 84 mm for MODUs and 120 mm for FPSO vessels.

The combination of a jump in volume and size presents manufacturing production line efficiency challenges and will require bulkier cargo consignments.

It is a similar story for drag anchors. Again, the O&G sector has valuable experience on which to build new installation strategies, but with the challenge of increasing volume and scale. For instance, common O&G drag anchors weigh 12–18 tonnes, whereas floating wind anchors are likely to be 35–40 tonnes. That means they can no longer be moved by road, necessitating fabrication or assembly close to port facilities.

The O&G industry is, of course, familiar with fabricating and lifting large assets such as production topsides – an experience that may be valuable for the floating wind sector. Additionally, with multiple floating assets required, a careful manufacturing mindset is needed to avoid costly design or fabrication errors that are replicated across multiple units.

Greater storage and handling capacity
An installation vessel with project personnel and equipment can be expensive, as much as £80,000 or more per day, so ensuring mooring equipment is in the right place, at the right time and ready for efficient mobilisation has a major impact on overall installation costs.

Effective delivery scheduling and good portside handling capacity can help to minimise storage requirements, but large temporary storage areas will be needed to accommodate the volume and size of equipment required to facilitate efficient installation campaigns. To meet this challenge and to build the capacity needed to support the floating wind industry, mooring companies need to invest in facilities designed for O&G operators.

Engage early for streamlined planning and budgeting
Engaging with mooring specialists early to create a concept model helps to inform vessel needs and procurement strategies. Even in the initial project stages, site data such as water depth, and metocean and seabed conditions can be leveraged to develop mooring scenarios. Specialists can generate multiple configurations of hull types and mooring arrangements to aid in concept development.

Such a mooring and anchoring feasibility study, informed by multi-sector experience, helps in developing the concept model and establishing installation timelines, vessel requirements and procurement plans. This information streamlines planning and budgeting and provides technical details for consenting and project viability assessment.

Holistic, risk-based O&M
A holistic, risk-based O&M approach can help to reduce ownership costs and extend asset life, particularly for wind farms with many floating structures using long dynamic power transmission cables. This approach, commonly used in the O&G sector, proactively tailors inspection schedules to reduce repairs by integrating risk assessment, monitoring, inspection and response digital twins.

The risk assessment process guides data collection frequency and type based on critical design aspects. It is used to establish inspection and maintenance schedules to prevent failures, with periodic updates to align with asset performance and degradation. Continuous monitoring, using low-power sensors and advanced communications systems, can assess a floating wind platform’s state of fatigue and corrosion, stability, motion, and condition of its ballasting systems and moorings.

Digital response twin technology further enhances understanding of floating asset behaviour by predicting the structural performance and options for life extension of an entire wind farm using a minimal set of monitoring sensors.

The digital twin is a near-real-time dynamic virtual model that uses the inputs from the sensors to build a long-term picture of normal and abnormal asset behaviour. This can be used to inform changes in inspection requirements, with opportunities to decrease inspection frequency if the response is better than expected.

A comprehensive risk mitigation strategy should include proactive and reactive methods, with a Mooring Emergency Response Plan outlining the options and steps to take in the event of a mooring system emergency.

Building on O&G experience
The O&G industry has a wealth of experience installing, operating and maintaining floating assets. While companies supporting floating wind operators face specific challenges, notably gearing up to meet the new demands of scale and equipment size, they also have opportunities to build strategies informed by O&G experience.

Acteon has supported the energy transition since the late 1990s and actively employs its cross-sector experience to benefit offshore renewable and energy transition projects, which now make up 40% of the company’s business. It has extensive experience in moving, mooring and anchoring large floating assets, and providing O&M and integrity services, for instance, response digital twins for floating assets and comprehensive monitoring systems, across sectors.

In the UK, Acteon is investing in readying its dedicated 25,000 m² of quayside storage in Montrose and 12,000 m² in Aberdeen to meet ScotWind developer needs. The company also has subsea O&M experts to help operators adopt strategic and proactive approaches that aim to simplify processes, streamline operations and improve the profitability of floating wind farms. These approaches include the use of low-logistics technologies designed to reduce vessel mobilisations, operational costs and carbon footprints.