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Fugro’s seafloor drilling equipment has gained further confidence after the completion of a number of investigations in Australia’s North West Shelf.
The company reported early in January that its Seafloor Drill 2 (SFD2) unit had completed a multi-site investigation which encountered variable calcareous sediments, with the results supporting a jack-up drilling campaign.
SFD units are remote drilling platforms designed to source a range of high-quality material samples – from soft clays through to hard rock – at depths of up to 120 metres below the seafloor, and is rated to water depths of up to 4,000m.
Using wireline coring tools sized between N and P, they can collect geotechnical samples with a diameter of 73mm. These also use aluminium core barrels to reduce weight.
Building on the capabilities of the primary SFD1 unit, SFD2 is also fitted with coiled tubing piezocone penetrometer testing (PCPT) equipment, and can automatically handle drill rods and tools whilst subsea. Test procedures such as seismic PCPT, vane shear testing (VST), surface T-Bar testing, ball probe testing (BPT) and piezoprobe testing can also be carried out.
The SFDs are fitted with four separate jacking legs that allow them to work on seabed slopes of up to 25 degrees. They can also be deployed with different footing options, depending on conditions.
The units are controlled remotely from the surface using work-class ROV telemetry and control systems, via an umbilical.
The concept was originally developed by Gregg Marine and later operated by Seafloor Geotec, a joint venture of Gregg and Fugro. Fugro’s first project with the SFD1 was in January 2013.
In the recent North West Shelf operations, SFD2 worked in water depths of up to 112 metres, performing in-situ testing and sampling to a total length of 323 metres. According to Fugro’s update, it was effective in sampling some of the most difficult seabed sediments from ultra-soft carbonate muds to highly weathered limestone.
Fugro’s Integrated Geosciences’ lead, Ian Finnie, helped scope the investigations and interpret the seabed conditions for the client, and noted in a statement: “Seafloor Drill 2 has proved to be ideally suited to the calcareous sediments that we have around Australia and is a game-changer in Fugro’s ability to support the offshore industry in Western Australia and Southeast Asia.”
When contacted by InnovOil Fugro was unable to disclose the operator on the North West Shelf project.
The success in Australia builds on a water depth record for seafloor drilling set by SFD1 in the Gulf of Mexico in April 2015. The unit carried out combined sampling and a PCP testing borehole to 62m below the seafloor, in water depth of 2,923m, in the Gulf’s Walker Ridge area.
The company could not disclose the next SFD deployment destination, but confirmed that “SFD1 is currently in Houston, Texas, while SFD2 is in Perth, Australia.”
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