Ship & Boat International eNews: December 2021
While seismic streamers remain a proven solution for marine and offshore surveys, they are not the most efficient means of data capture. A seismic ship towing up to 20 streamers can generate significant drag, which takes a toll on overall fuel consumption per survey – hardly ideal for diesel-fuelled vessels travelling at slow speed.
One alternative has been to deploy ocean bottom nodes (OBNs), which are powerful data recorders that can be positioned at various water depths, descending as far as thousands of metres below the surface. However, moving OBNs from one location to another isn't straightforward: sending dive squads to extreme depths can be dangerous, while using ROVs or support ships to position the OBNs is costly and carbon-intensive. What if these OBNs could autonomously switch their positions and move from A to B without assistance, though? That’s the challenge that inspired Blue Ocean Seismic Services (BOSS) to develop its ocean robotic seismic robotic vehicle (OBSrV) – in simple terms, an autonomous, movement-capable OBN.
While OBN technology is commonly associated with offshore projects, Simon Illingworth, CEO and MD of BOSS, tells Ship & Boat International: “Three to four years ago, 70% of our business was planned to be in offshore oil and gas exploration, but we’re now seeing more demand for carbon capture and storage applications in offshore reservoirs, and increased interest from the offshore wind sector.” In autumn 2021, a prototype of the OBSrV undetook a week of seismic trials in the North Sea. The vehicle was tested at various weights for up to 14-16 hours each day, and, despite the harsh environment, managed to successfully couple to the seabed and gather high-quality ocean bottom seismic data.
The OBSrV is just over 1m-long and can be launched and recovered autonomously. Once launched into the water, the unit automatically makes its way to its pre-designated subsea spot. It can then reposition to another location autonomously. The motorless vehicle relies on up- and down-currents to manoeuvre, and its seismic sensors are powered by Li-ion batteries – sufficient to provide eight weeks’ endurance before a recharge is required. Depending on sea conditions, the unit can move at a speed of 1-2knots.
In this way, operators could reduce their reliance on support vessels and personnel, while also benefiting from shorter survey turnaround times. BOSS estimates that the technology could even reduce seismic survey costs by more than 50% in the long term. The company is now planning further seismic trials in the Gulf of Mexico, North West Australia and the North Sea in the first half of 2022, before progressing to the commercialisation phase.