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Pipelines cross harsh terrain
Two 800-kilometre onshore pipelines form the backbone of Sakhalin-2. They run the length of Sakhalin Island, over steep mountains, under rivers and through swamps and forests.
The pipelines carry oil and gas from three often ice-bound offshore platforms to an ice-free port in the warmer south of the island for shipping. The first oil arrived at Sakhalin-2’s Prigorodnoye port in December 2008, and the first gas in February 2009. This allowed Russia to export energy from its eastern coast to new markets for the first time.
Harnessing the cold
The pipelines were laid in mountain areas where melting snow and rainfall cause landslides in swampy areas in the lowlands that are difficult to access in winter. Rainfall is heavy in autumn. In summer, temperatures climb above 30 degrees Celsius (86° Fahrenheit), but in winter, they can drop to -45°C (-49° Fahrenheit) and snow typically falls several metres deep. Construction in swampy areas was mainly carried out in winter when the frozen earth could support the weight of tracked vehicles and other heavy equipment.
Near rivers and in some swampy areas, workers built roads made from ice, pouring water on wooden beams and waiting for it to freeze before adding more layers of water. In the same areas, pipelines are weighed down with concrete, to prevent them from floating to the surface when the ground thaws.
Some 500,000 tonnes of steel went into building the onshore pipelines, which run through forests, swamps and wetlands. They cross plains and mountains and more than 1,000 rivers and streams.
Sakhalin Island is home to Steller’s sea eagle. With a 2.5 metre wingspan it is one of the world’s largest birds. Sakhalin Energy sought to protect this rare and beautiful species by limiting activity inside a buffer zone around nests and suspending work during nesting periods.
Pipelines cross seismic faultline
The pipeline route crosses the seismic faultline in 19 places. Each day one pipeline can carry up to 1,800 million standard cubic feet of gas, the other up to 180,000 barrels of oil. Designing and constructing them to withstand earthquakes was crucial as Sakhalin Island lies just west of an earthquake-prone area known as the Pacific Ring of Fire. Some 2,000 people died in a major earthquake in Neftegorsk in the north of the island in 1995.
All pipeline welds were tested for defects with X-rays. In addition, pipeline welds on sections crossing faults were tested with ultrasound. Those pipeline segments are also made of a type of steel that is flexible enough to withstand a degree of seismic activity. They are laid in trenches so they have room to move. The trenches are designed to drain water to prevent ice from building up and immobilising the pipelines.
As an additional safeguard, the pipelines are fitted with more than 150 remotely-operated valves that can stop the flow of oil or gas. Pressure and temperature are monitored at each valve as part of pipeline leak detection systems. All the pipelines are buried at least one metre below the surface and Sakhalin Energy has largely completed work to restore vegetation on the land above them.