"The partners in the project are convinced that it will be functioning by autumn 2011," EON Ruhrgaz chief executive Bernhard Reutersberg said in an Interfax news agency report.
Reutersberg acknowledged, according to Interfax, that there had been unexpected problems with the pipeline regarding clearance from transit countries, several of which have opposed the project.
The Baltic states and Poland have objected to Nord Stream, concerned at being bypassed by a major Russian gas supply route to Europe, which dependsheavily on Russia for energy.
The Nord Stream consortium is led by Russia's Gazprom, with 51 percent, while EON Ruhrgas and Wintershall Holding have 20 percent each and Holland's Gasunie owns nine percent.
Earlier this month, German Chancellor Angela Merkel championed the project, which besides angering eastern European states has worried environmental groups.
"I will promote this project, which is in the interest of many countries," Merkel said after talks with Russian President Dmitry Medvedev in Berlin.
"I will strive to overcome all objections," she added.