The wind farm, which is being built 32km north of the Baltic island of Rügen, will feature 80 Siemens turbines, with 34 currently installed.
The latest deal requires JDR to deliver pre-commissioning, testing and termination services for the project.
Siem Offshore selected JDR to provide onshore planning and procedures, project management, mechanical installation, cable containment, termination, test, modification and reporting.
Siem Offshore chief operating officer Günther Bakker said: "We brought JDR into the Baltic 2 project due to their full support team capability and extensive experience in offshore power cable operations.
"In field, their work has been professional with on-time delivery. We are delighted to extend their role in the project."
Upon completion, the Baltic 2 wind farm will generate 1,200 gigawatt hours of electricity per year for about 340,000 homes and save 900,000 tons of CO2.
Earlier in 2015, EnBW Energie Baden-Württemberg agreed to sell its 49.89% stake in the Baltic 2 wind farm to Macquarie Capital for about €720m.
EnBW will retain the remaining interest in the wind farm, which is expected to be commissioned in spring 2015.
Image: The Baltic 2 offshore wind farm is being built 32km north of the Baltic island of Rügen. Photo: Courtesy of xedos4/FreeDigitalPhotos.net.
