The European economy gets about 20 percent of its natural gas from Russia, though most of that runs through Soviet-era pipelines in Ukraine. Russia cut gas supplies to Ukraine, most recently in 2009, because of contractual disputes.
Russia's state-run news agency RIA Novosti reported Wednesday the Ukrainian government believes "gas wars" with Russia are no longer possible because of European diversification and Ukrainian shale natural gas reserves.
British exploration company JKX Oil & Gas said last month most of its hydraulic fracturing operations in Ukraine were successful.
JKX started its multistage hydraulic fracturing operation at its Rudenkovskoye license area in eastern Ukraine in early July.
The Ukrainian government said there may be enough natural gas in shale reserve areas to meet the country's needs without imports.
Royal Dutch Shell in January signed a $10 billion contract to explore Ukrainian shale reserves.
European consumers, meanwhile, recently secured natural gas supplies from Azerbaijan, though deliveries are a few years away.