STRAIT AREA: One of the world’s largest semi-submersible crane vessels will be in and out of the Strait of Canso all summer.
On June 15, a specialized, semi-submersible crane vessel called Thialf entered the Strait of Canso. This vessel is the second largest of its kind in the world.
Strait of Canso Superport Corporation CEO Tim Gilfoy said the vessel is on contract to Exxon Mobil to conduct decommissioning work on the Sable Offshore Energy Project.
Merle MacIsaac, public and government affairs with ExxonMobil Canada Ltd., explained the Thialf is supporting the final phase of decommissioning, which ceased production in December 2018. Thialf has capacity for a crew of approximately 500, but for the work at Sable, it is expected to be supported by a crew of approximately 300, made up of international and local crew.
He said the schedule for removals work has been affected by public health restrictions and related travel restrictions.
“We expect the vessel to make about four to six trips to [Chedabucto] Bay between now and the fall staying there each time for about a week to 10 days,” MacIsaac told The Reporter.
In 2017, Exxon Mobil, as operator of the project, started the decommissioning process by plugging wells and preparing offshore platforms for removal. This year, ExxonMobil Canada began the final phases which include the removal of offshore and onshore facilities, along with pipeline abandonment activities, according to MacIsaac.
Two weeks ago, Thialf, operated by Heerema Marine Contractors, moved to the Sable field to begin removals, MacIsaac explained, noting the vessel will execute a sequence of separate lifts of platform components (e.g. topsides and jackets) using a reverse-installation method.
After taking platform components onboard at the Sable field, MacIsaac said Thialf sailed to Chedabucto Bay and was met by a tug-and-barge combination.
Gilfoy said the Thialf is transferring structures that were once part of the Sable Project from the heavy lift vessel to barges belonging to the Strait of Canso Superport Corporation.
“We’re handling a lot of the barges associated with that,” Gilfoy explained. “We have barges tied up here in the Strait of Canso that are serving that vessel out there. The barges go out to meet the vessel out in Chedabucto Bay and there’s some transfers of heavy structures taking place out there.”
The components will be loaded onto the barge, and then sea-fastened for the transatlantic voyage to a yard in the United Kingdom that specializes in dismantling, recycling and disposing of offshore facilities. MacIsaac said this sequence will be repeated several times. In one case, the components will be loaded and sail overseas directly from the Sable field.
During the campaign, MacIsaac said Thialf will support the mitigation of potential commercial hazards, such as the removal of unburied portions of pipeline near the offshore platforms. Several support vessels, as well as helicopter transportation, are also being used to support the removal campaign.
In parallel with the offshore work, MacIsaac said ExxonMobil continues to execute its plans for the demolition of its onshore plants, including a fractionation plant at Point Tupper and the Goldboro Gas Plant. Also in scope for the onshore portion is the abandonment of an eight-inch-diameter pipeline that connects the two plants.
In March, the onshore crew was mobilized by key contractor, Golder, and in April processing facilities at Point Tupper were removed.
MacIsaac said onshore and offshore work is being carried out in compliance with all relevant health orders in place to protect the public, and to prevent the spread of the novel coronavirus (COVID-19). Heerema has a comprehensive plan to closely monitor, screen for, and prevent exposure to the coronavirus. In light of various travel restrictions and other guidance from relevant authorities, Heerema and ExxonMobil have reviewed, revised and implemented this plan and procedures to ensure the work is carried out safely.
“These activities are consistent with commitments made in the Sable Project’s original approved development plan,” MacIsaac noted. “Completing the work demonstrates that Nova Scotia’s offshore oil and gas can be developed safely and responsibly.
“ExxonMobil is monitoring the situation closely. Our focus is the safety and health of the workforce, and to do our part to limit the spread of the novel coronavirus in the community.”
Gilfoy added that this type of project isn’t just great for the Superport Corporation, but for local businesses and the entire region.
“It’s quite meaningful for us, but it’s very meaningful for the greater Strait area,” he added. “There’s a lot of spin-off work associated with looking after all the needs of a project like this. There’s ourselves, Mulgrave Machine, and Superport Marine.
“It does highlight the importance of having a common user facility here that other companies can utilize to generate economic activity here.”