The company plans to increase output from the Prinos, Prinos North and Epsilon fields to 10,000 barrels per day by 2016.
Under the programme, Energean will drill 15 wells and install two new unmanned platforms for the Prinos North and Epsilon fields.
They will be tied back to the existing infrastructure the company currently operates.
The wells will be drilled using a Glen Esk drilling rig, which Energean has purchased from KCA Deutag.
Drilling is expected to start in early December and the new rig will be re-named Energean Force.
Energean Oil & Gas chairman and CEO Mathios Rigas said: "Energean has invested more than $250m since 2007 and managed to keep Greece on the global map of hydrocarbon producing countries.
"Prinos, the only proven and producing oil field in Greece, has already produced 115 million oil barrels, even though reserves were initially estimated at 60 million oil barrels."
"Now Prinos is entering a new era, as Energean investments and scientific surveys have proven that there is significant scope for extracting additional production through the drilling of new wells and through the extended use of enhanced oil recovery techniques, at a time during which the Greek hydrocarbon sector is set to play a significant role in the attempt to lead Greece’s economy back to growth again, after a seven-year period of recession."
ERC Equipose’s Competent Persons Report estimates that the recoverable oil reserves (2P) of Energean’s assets in the Gulf of Kavala will cross 30 million barrels and 2C resources will be 27 million barrels.