Russian gas giant Gazprom Neft says it has made a new discovery containing 255 million tonne of oil equivalent (ca.1.8 bn boe) in place on the Ayashsky license block, in the Okhotsk Sea.
The Ayashsky block in the Okhotsk Sea forms part of the Sakhalin-3 project. The block is in the northeastern part of Sakhalin Island’s continental shelf, 55km away from the coast.
The firm says that "cutting-edge technological solutions" applied to the construction of the well enabled Gazpromneft-Sakhalin to build the prospecting and appraisal well during a narrow window of ice-free period at the Okhotsk Sea, on time and without incident.
Specifically, riser-free sludge-removal technology made it possible to control the stability of strata surrounding the borehole, as well as eliminating any possibility of geological material entering the marine environment.
Drilling, in 62m water depth, was carried out using a rotary steerable system, which allowed the maintenance of vertical control with automatic corrections. This enabled the use of the most “aggressive” penetration mode, shortening the construction time and minimizing the number of run-in-hole/run-out-of-hole (RIH/ROOH or “tripping”) operations.
Core samples running to 162m were taken from anticipated productive strata (horizons) for the construction of the 2,700m-deep well, with extensive open- and closed- geophysical and hydrodynamic borehole exploration works undertaken. A detailed assessment of these reserves will be prepared by mid-2018.
Gazprom Neft is the operator of the Dolginskoye oil field, at which geological prospecting works are currently ongoing, as well as the North-West block of the Pechora Sea, the Kheisovsky block in the Barents Sea, the Severo-Vrangelevsky block, covering the East-Siberian and Chukhchi Seas, and the Ayashsky block in the Okhotsk Sea.
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