The company said two appraisal wells in Norwegian waters of the North Sea have "reservoir properties that exceed expectations."
Bernd Schrimpf, managing director for regional subsidiary Wintershall Norge, said the assessment helps the company plan the next stages.
"We are now in a position to begin evaluating a possible development [of the site]," he said in a statement.
Wintershall said it estimated the reserve potential at 120 million to 230 million barrels of oil equivalent, with oil reserves contributing to the majority of the potential.
The company said the development likely concludes the appraisal phase of the Skarfjell campaign.
Wintershall's estimates were confirmed Wednesday by the Norwegian Petroleum Directorate, the country's energy regulator.