Berkut was designed with 45 platform wells: 28 oil producers, 16 water injectors and one dedicated drill-cuttings reinjection well. The integrated topsides contain drilling, wellhead, production-processing, water-injection, utility, accommodation and helideck facilities. Long extended-reach trajectories, with horizontal displacement of at least seven kilometres in the development design, enable access to the Arkutun-Dagi reservoirs without satellite wellhead platforms or subsea production tie-backs. The approximately 42,000-tonne topsides were installed by float-over onto a concrete gravity-based structure placed on the seabed in 2012. Friction-pendulum bearings between the topsides and substructure provide seismic isolation. The platform was engineered for magnitude-nine earthquakes, temperatures down to approximately −44°C, waves up to 18 metres and sea ice about two metres thick. Its autonomous electrical system includes four 60-megawatt gas-turbine generators and a separate emergency source. Permanent systems also support drilling control, production monitoring, injection, metering, emergency shutdown and crew accommodation. Produced wellstream leaves Berkut through an approximately 25-kilometre subsea connection to the Chayvo Onshore Processing Facility, where full oil and gas treatment is performed. Stabilised oil then joins the Sakhalin-1 export system and travels through the 24-inch, approximately 226-kilometre pipeline across Sakhalin and the Tatar Strait to the De-Kastri terminal. Crude is stored onshore and loaded to ice-class tankers through the terminal’s single-point mooring; gas is routed to domestic supply.