A subsidiary of Russian energy company Gazprom Neft said it started drilling its single-well program in the arctic waters of the Pechora Sea.

The subsidiary, Gazpromneft-Sakhalin, started exploratory work in the Dolginskoye field on the continental shelf in the Pechora Sea.

The company said it was working on the field during ice-free months of the summer.

Warming trends are leaving parts of the arctic ice-free for longer periods of time, giving energy companies more time to try to exploit the untapped reserves.

Gazprom Neft is the oil arm of the Russian energy company Gazprom, which was the target of Greenpeace demonstrations against arctic exploration this year and last.

Gazprom Neft said Monday its drilling operations in the region are certified by national and international authorities as safe and it was using advanced technology to minimize the environmental impact of its exploration activity.

The company estimates the Dolginskoye field holds more than 200 million tons of oil equivalent. It's working alongside energy services companies Schlumberger and Weatherford on the Pechora Sea field.