World's fastest ROV? - Project ROST

The team in Sperre ROV Technology did not hesitate for a second when they were asked if they wanted join a project to develop a super-fast ROV for the seismic company, Petroleum Geo-Services
The seismic company, Petroleum Geo-Services ASA (PGS), wanted a safer and more effective way to remove unwanted fouling from the outside of the GeoStreamers. As unwanted growth degrades the signals picked by the sensitive sensors inside the Geostreamer, effective cleaning is critical to ensure operational performance. They contacted Sperre, asking if they were interested in developing a super-fast ROV that could streamline the cleaning operation: Project ROST ("Remotely Operated Streamer Tool") was launched.

Today's cleaning method uses a so-called Streamer Cleaning Unit (SCU) that is manually attached and released at the start of the GeoStreamer. The waterflow drives the SCU backwards along the streamer in lengths up to 8km.

Traditionally, all cleaning has been carried out from a workboat, including the assembly of the SCU onto the streamer. For HSE purposes, PGS wanted to minimize the use of workboats. The solution fell on an operation consisting of an ROV and a LARS system.
- What was special about this project was that this operation required the ROV to be put into the sea at speeds up to 5 knots. This is very unusual, says Thor Olav Sperre. He then explains that it required innovating thinking in terms of design on both the ROV and the LARS system to deliver on the request, where the latter is developed by Lidan Marine AB in Sweden in cooperation with Sperre.

- During the spring 2013 we completed a prototype and tested the concept. After the tests, we found many answers as to how the final design had to be in order to achieve the desired speed, he says.

At the end of 2014, the final design began to take shape and new tests were carried out in Heddalsvannet, Notodden. All development in design (mechanical / electronics / programming) and assembly has taken place at Sperre's premises in Notodden. By 2017, PGS has conducted several tests at high speed to test the system to its fullest. The highest recorded speed was over nine knots! CFD analyzes have been used on hull and buoyancy components on the ROV.

- We have done CFD analyzes on the hull and buoyancy components in the ROV, and we have focused a lot on hydrodynamics to achieve this speed, concludes Thor Olav Sperre.