Bespoke buoyancy solutions

Midwater arch buoyancy systems can play a crucial role in supporting floating offshore wind turbines by providing essential buoyancy and stability to power cables.

This innovative system comprises a submerged arch-shaped structure with modular buoyancy, ensuring power cables remain at an optimal depth for both stability and efficient power generation. By using this technology, offshore wind farms can harness wind energy resources even in deeper waters.

Key benefits:

• Provides cable stability, reducing dynamic movement and friction allowing for enhanced fatigue life
• Half disk buoys are readily adjusted in size to accommodate uplift requirements allowing customisation to project-specific requirements
• Simplistic design incorporates a small number of components that facilitates cost effective manufacturing, assembly and maintenance processes
• Half disk buoys are rotationally moulded resulting in consistent high volume manufacturing, constant wall thickness and enhanced durability
• Components are recyclable at end of life decommissioning

Designing systems for hydrocarbon extraction in deep and ultra-deepwater fields involves considering water depths, seabed conditions, high pressures, and temperatures. Ultra-deepwater fields have led to various riser solutions, such as steel catenary risers, flexible flowlines, single leg top-tension risers, and hybrid riser towers (HRTs). HRTs, comprising multiple risers around a core pipe supported by a buoyancy assembly, are prominent in West Africa due to their stability and success in several projects.

HRTs typically include 4-12 risers anchored to the seabed and supported by a top air can, with buoyancy provided along the bundle and at upper and lower riser tower assemblies (URTA and LRTA). This buoyancy facilitates surface tow-out and contributes to vertical stability.

In scenarios with low wax-content oil or high wellhead temperatures, external ‘wet’ insulation coatings are used for production and gas lift risers. Here, HRT syntactic foam provides buoyancy, aiding surface tow-out and long-term stability while reducing tensile loadings within the central tendon pipe. The foam is designed to minimize exposure to elevated temperatures, as it loses mechanical properties when heated.

Balmoral's extensive development and project experience have led to unrivaled knowledge of syntactic foam design for depths up to 3000msw and temperatures up to 55°C. For temperatures up to 30°C, standard syntactic foam components are used, while for 30-55°C, Balmoral developed DURAFLOAT HT™, a high-Tg epoxy syntactic foam system. This system offers superior mechanical properties and reduced performance loss with increased temperature, as demonstrated in the CLOV project in Block 17, offshore Angola.