The vessel recently passed the ‘KP660’ point close to the border of the Bulgarian Exclusive Economic Zone.
It is currently proceeding along the section of the TurkStream route toward the Kiyikoy settlement, in accordance with permits granted by Turkey.
By mid-February, 884 km (549 mi) of pipes had been laid for both strings of the pipeline system, accounting for roughly 48% of the offshore section.
TurkStream, due to come onstream by the end of 2019, will comprise two parallel gas pipelines stretching 930 km (578 mi) from Russia across the Black Sea, each with a diameter of 81 cm (32 in.) and annual throughput capacity of 15.75 bcm.
This will be the first pipeline of its size to be installed at a water depth of up to 2,200 m (7,218 ft), Gazprom added.
One of the pipelines will be dedicated to the Turkish market, while the other will provide gas to countries in southern and southeast Europe.
Gazprom subsidiary South Stream Transport is responsible for the offshore construction.