A semi-submersible heavy-lift vessel and a jackup drilling rig are in the Halifax Harbour to do the decommissioning work for the next and final stage of the Sable Offshore Energy Project.

"Its job will be to be involved in capping the wells that are out there, permanently sealing the wells that were used to produce natural gas," says Merle MacIsaac, spokesperson for Exxonmobil Canada.

The Sable Offshore Energy Project was the first natural gas offshore project in the country when production began in 1999.  The Noble Regina Allen jackup drilling rig will begin work on the wells later this month, weather permitting.

There are 22 wells in total, with some up to depths of five kilometres under the ocean floor.

"Any natural gas project has a beginning, a middle and an end. The field is mature," says MacIsaac.

The timeline for decommissioning is expected to take several years. Experts say the vessel, which is part of the first step, is going to be working at the site for two years.

MacIsaac says the project will officially be complete between 2020-21 if everything goes as planned. 

"After the sable project is complete and any other projects that are operating here are complete, we will still have access to natural gas in North America," he says. 

The rig has a drilling depth of 35,000 feet, with the legs stretching more than 500 feet. Until the  vessel can begin work at sable, onlookers will see it in Halifax Harbour.      

Lane Farguson of the Halifax Port Authority says it's business as usual, as the harbour is equipped to handle vessels of this size.

"We do have regulations and practices in place to ensure the safe navigation and we work with all of the different harbour groups to make sure that takes place as well," says Farguson.

Exxonmobil officials say eager onlookers will be able to see the large vessel and rig up close when she docks near Darmouth's Woodside neighbourhood in the coming days.  

With files from CTV Atlantic’s Suzette Belliveau.