Offshore divers perform a variety of tasks for the offshore industry. While much of their seabed work involves the inspection, maintenance, and repairs, they also assist with pipeline operations and the installation and upkeep of mooring systems. Divers sometimes operate at depths of up to 600 feet. Beyond this, specially engineered vehicles are required to manage the extreme conditions.
Remotely operated vehicles (ROVs) have reduced the reliance on divers. With advancements in technology and capabilities, the offshore industry increasingly depends on ROVs for drilling support and subsea construction to enable deepwater exploration. Some ROVs can operate at extreme depths of up to 10,000 feet, and their umbilical cables provide unlimited power supply. This allows for continuous operation as needed. Another key advantage is that they eliminate the need for personnel underwater, enhancing safety and reducing operational risks.
Offshore divers and ROVs could be highly effective at performing IMR operations at significant depths. However, operations in the splash zone—the area immediately above and below the mean water level—presents challenges for both divers and ROVs. Additionally, certain projects can only realistically be carried out using robotic solutions specifically designed for the splash zone.
Safety, cost-efficiency and CO2 emissions
The splash zone is one of the most challenging IMR areas offshore. Strong winds, currents, and large waves affect diving safety. In the North Sea, wave heights can reach 10-15 metres or higher. But even 2-metre waves, or currents alone, can cause crush injuries. The splash zone environment can also make it challenging to operate ROVs. The umbilical, while providing unlimited power supply, can also be a disadvantage in this environment due to drag and motions. In extreme situations, operations may have to be called off to minimise risk of damage to the equipment.
Delays and cancelled operations can result in significant additional costs. Although rates vary across continents, offshore divers require a large team topside, with support vessels frequently carrying more than 50 personnel on board. As the scope of an operation expands, so too does the size of the team and the operational costs. In the North Sea, the total cost of an offshore diving operation can easily surpass 100,000 euros per day. ROVs can cost anywhere from a few thousand to millions of euros. These costs are reflected in high contract charges. In addition, there are costs related to personnel, support vessels, and equipment.
OceanTech’s splash zone operations do not require offshore divers or ROVs. Our inspection capabilities provide a complete view of the underwater environment from a topside control unit. We also use temporary lifting equipment. Neither ROVs, divers, or crane vessels are required to guide our equipment into position.
All of our robots and tools are operated remotely from the topside, enabling unmanned operations near structures in confined spaces. Our solutions also reduce waiting times for favourable weather conditions, minimise downtime, and offer significantly lower daily rates compared to ROV operations. As our access robots use existing infrastructure, we can execute operations without the support vessels typically needed for divers and ROVs. This approach cuts emissions and lowers the risk of oil spills.
Tasks requiring specialised splash zone solutions
While not entirely unfeasible, certain operations in the splash zone are exceedingly difficult to perform using divers or ROVs. These include pipe and bend interior cleaning, FPSO riser receptacle cleaning, caisson modifications, riser guide frame modifications, fairlead repairs and replacements, sleeve repairs, and concrete repairs.
Pipe and bend interior cleaning: Cleaning the interior of confined spaces like pipes and bends requires specialised nozzle technologies capable of navigating tight areas and delivering effective cleaning force. This task is typically beyond the capabilities of divers or ROVs due to their limited access and inability to provide the required precision.
FPSO riser receptacle cleaning: The combination of access constraints, efficiency requirements, and the need for precision makes riser receptacle cleaning virtually impossible without specialised robotic systems designed to operate effectively in the splash zone.
Caisson and riser guide frame modifications: In the splash zone, caisson modifications, riser guide frame modifications, and clamp installations are either highly challenging or impossible for divers and ROVs to perform effectively.
Fairlead repairs and replacements: These projects require heavy lifting, precise positioning, and secure fastening, which are beyond the capabilities of ROVs due to their limited dexterity and force control.
Sleeve repairs: Sleeve repairs in the splash zone are impractical and unsafe for both divers and ROVs. Specialised robotic systems, which can maintain stability and perform high-precision tasks in turbulent environments, are essential for completing these repairs effectively.
Concrete repairs: Divers face safety risks and limited control, while ROVs lack the dexterity and stability required for accurate material application and bonding in dynamic environments.