New regulations, among other things, require an environmental impact study and public consultations before exploration can start, the Environment Ministry in Vilnius said on its website.
Notably, along with conventional natural gas, the company plans to extract both shale gas, and tight gas.
Sources say PetroChina wants a share of eastern Siberian gas fields.
Rosneft and ExxonMobil are progressing with a proposed liquefied natural gas (LNG) project on Sakhalin Island in the Russian Far East with the start of the contractor selection process for design and engineering work.
A new study indicates that astroblemes in Ukraine may be a good place to start drilling.