Gazprom said buffer gas would be sent through the second string of the dual pipeline system in a matter of days. Commercial natural gas should start making its way to European consumers by the end of the year now that the offshore and onshore sections are connected on the Russian coast in the Portovaya Bay near Vyborg.
The system is part of a network of pipelines planned to diversify Russian natural gas exports to European consumers. The first leg of the pipeline system went into service last year.
Both lines, once fully operational, will transport about 1.9 trillion cubic feet of Russian gas each year to European consumers for at least 50 years.
In early May, the consortium behind the project said it would spend the rest of the year examining the feasibility of adding up to two additional pipelines to the network.
The consortium this week asked for permission from the Estonian government to conduct a study in its economic zone through the end of 2014 for additional Nord Stream lines, though the government said it wasn't necessarily committed to the project.