Sea trials plot course for autonomous subsea survey vessels

The UK’s Blue Ocean Seismic Services has developed the ‘nodes’ to acquire high-quality imaging (OBS) data from the ocean floor for the development of carbon capture and storage (CCS) projects, offshore wind farms and oil & gas fields.

The company, which has received backing from bp Ventures, Woodside Energy and Blue Ocean Monitoring, said their underwater vehicles will make offshore seismic surveys more affordable, faster, safer, more environmentally friendly and less carbon intensive.

The autonomous ocean bottom seismic robotic vehicle (OBSrV) nodes ‘fly to their set location, land on the seabed, upon command relocate to another position and land, and then finally resurface for recovery,’ explained Simon Illingworth, managing director & CEO, Blue Ocean Seismic Services.

“It is essential that the node couples well to the seabed and doesn’t move in currents,” he added. “Typically, this is done by making them heavy, but we need them as light as possible to be able to ‘fly’”.

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A snapshot of acquired data can be sent to customers via satellite, but most of it is saved to a hard drive with a capacity to acquire 620TB of data during a 60-day survey.

The nodes are powered with lithium-ion batteries and will initially be taken to sea in crewed vessel, but future plans involve deployment via autonomous vessels, Illingworth said.

Marine seismic data acquisition currently requires streamer cables to be laid from the aft of a diesel-powered vessel and towed on a designated track line traveling at two-to-five knots, which is not suitable for many locations and environments.  The main alternative is ROV positioned Ocean Bottom Nodes which is costly and both solutions are carbon intensive.

In the latest set of tests in Plymouth, the North Sea and Australia the company said it has moved towards confirming the effectiveness of command-and-control systems, underwater flight performance, seismic coupling and active seismic data acquisition. In the North Sea, Blue Ocean Seismic Services said it acquired additional cycles of active seismic data with its AP-OBSrV alongside conventional ocean-bottom nodes, and confirmed the ability of the AP-OBSrV to maintain a close seismic coupling with the seabed, particularly where cross currents exist. The company was also able to test engineering solutions for optimisations identified in trials carried out in August 2021.

Blue Ocean Seismic Services will now continue its progression towards commercial operations in 2024, starting with the assembly of up to 250 OBSrV version 1 nodes in batches, with pre-commercial trials in H2 2023.