On 4 October 2017, Gazpromneft announced a giant oil discovery on the Ayashski block offshore Sakhalin island in Russia's Far East. Initial in-place resources are estimated at 1.86 billion barrels of oil equivalent, making the Neptune field the biggest discovery in Russia and one of the largest globally in 2017. This opens a new growth area for Gazpromneft with big production potential post-2025. Neptune could produce up to 120,000 b/d at peak. This would allow Gazpromneft to offset decline from its mature asset base in West Siberia and boost company cash flow in the late 2020s.