"Oil will come from… geologically complex areas," Birol stated on Monday. "The costs of oil and gas production, extraction will go up and… oil prices may gradually increase."
On Monday, Birol spoke at the Center For Strategic and International Studies where he delivered the IEA's annual World Energy Outlook.
Birol added that he is seeing a substantial rise in natural gas markets in Asia driven by growth in China, India and Southeast Asia.
Major international energy companies, including Royal Dutch Shell — which ceased an offshore project in Alaska — have recently faced high production costs from complex drilling environments.