The Sakhalin 2 Pipeline Project involved the construction of offshore and onshore pipelines as part of the overall development of the Piltun-Astokhskoye and Lunskoye oil and gas fields, offshore Sakhalin Island in the Sea of Okhotsk, north of Japan. Construction of the pipelines began in early 2004, and was completed in 2008, with commissioning taking place in 2009.
At the peak of construction, around 8,000 people were employed on the project, approximately 30 per cent of whom were Sakhaliners, with most of the others being from mainland Russia. Around 500 expatriate employees, from Europe, the Americas, and Australia, also worked on the project.
Project scope
The pipe used for the project ranged between 14 and 48 inches in diameter, with wall thicknesses varying from 7.1 to 30.2 mm, and made from X52, X60, X65, and X70 steel. The onshore pipelines totalled 1,600 km in length, and 300 km of offshore pipelines were constructed.
The Sakhalin pipelines are located in three main groups between the offshore platforms, situated to the northeast of Sakhalin Island in water depths of up to 50m, and an onshore processing plant situated near the coast in the northeast of the island and an LNG plant in the south of the island. The northern offshore area has an ice season of six to seven months, whereas the southern part of the island is subject to a shorter ice season and less severe conditions, which allow the year-round export of LNG and crude oil from the island. The two northern groups of the pipelines transport oil, gas, and condensate in single and multi-phase states from three offshore production platforms to the onshore processing plant, where the well streams are separated and treated.
There is also a pipeline from the onshore processing plant to Lunskoye-A, the most southerly offshore platform of the fields, transporting regenerated mono-ethylene glycol (MEG) back to the platform for re-use in the multi-phase pipeline.
The third group of pipelines transports gas and oil from the onshore processing plant to the LNG plant and the oil export terminal in the south of the island. Another crude oil loading pipeline runs from the oil terminal to a single-buoy mooring of the tanker-loading unit.
The pipeline facilities include approximately 150 block-valve stations and 19 pig trap stations, as well as a fibre optic cable – for communication and control purposes – running the length of the lines. The offshore pipelines also involved the installation of seven platforms risers and three shore approaches.
Special sections for the onshore pipelines were needed for approximately 700 road crossings, 1,100 water crossings, 18 rail crossings, 19 active seismic fault crossings, 80 electrical transmission line crossings, and more than 100 underground services crossings, as well as more than 70 unstable ground areas (landslides, mudslides, and avalanches).
Constructing pipelines on Sakhalin Island
The Sakhalin project was Russia’s first offshore development, which meant that during construction, the existing regulatory framework for the energy sector was still geared to onshore development activities.
In addition, the construction of the pipelines was characterised by various seasonal limitations. These included the end of the winter thaw period, which is approximately one month long, and makes it impossible to work in many areas.
Robert Boulstridge was construction manager on the Sakhalin Energy project between 2004-07. Mr Boulstridge said “In the case of many peat/bog areas, it was only possible to excavate and lay pipe in the middle of winter when the ground was frozen. Similarly, work on crossings of salmon rivers was limited by various designated spawning season constraints and these were different for different salmon species and in different locations on the island.”
The ground on Sakhalin is frozen for approximately four to five months of the year. “The weather on Sakhalin can be very harsh with normal mid-winter daytime temperatures of -20 to -40°C. These temperatures posed obvious personal safety hazards, and ordinary manual activities became very difficult.” In order to mitigate the hazard to workers, ‘warm shelters’ were provided on the work site so that workers could have a break from the cold every two hours.
While snow isn’t too frequent on Sakhalin, when it occurs it is often as one to three day blizzards, resulting in large quantities of snow being deposited in a very short period. “This made all roads impassable until cleared and access to off-road sites was blocked for considerable periods,” says Mr Boulstridge.
Horizontal directional drilling (HDD) was used to cross six watercourses with 12 individual HDDs between 500–1,000 m in length, for the 20 inch, 24 inch, and 48 inch pipelines.
Securing seismicity
A large part of the onshore pipeline route passes through areas of landslides, mudflows, and avalanches. “The general engineering approach in these areas was to estimate the unstable slip-plane locations and install the pipelines below this level. This necessitated the removal of large volumes of material on some occasions,” says Mr Boulstridge.
Seismic fault crossings constituted the most difficult technical aspect of the pipeline engineering design, taking several years to complete due to the complexities of the fault systems, as well as developing the designs for each individual crossing. There are two main fault systems on Sakhalin: the Goromay Fault and the Kliuchevskoi Fault. The design objective was to minimise the number of fault crossings, despite the fact that the pipeline route runs parallel to the Kliuchevskoi Fault over much of its length. The final design incorporated one crossing of the Goromay Fault and 18 crossings of the Kliuchevskoi Fault. “Fault movement does not normally occur at surface level when the seismic event has a magnitude of less than 6.5, but Sakhalin has experienced events with magnitudes greater than this,” Mr Boulstridge says.
Because the crossings were designed for a 1,000 year return period, which involves potential ground movement and pipe displacements of up to 4.6 m, the pipelines have been designed to withstand large movements by deforming without rupture or loss of containment. Crossings are configured in a dog-leg shape, over a length of approximately 1 km, and cross the faults at specific angles, typically 45°C, to minimise compression stress on the pipe. “The crossings are characterised by very shallow trench sides, with an infill of a mixture of special round-particle-shaped sand, and lightweight expanded clay aggregate to allow the pipeline to move out of the trench with minimal resistance,” says Mr Boulstridge.
In addition, the detailed design aspects were complicated by the need to avoid water build-up in the trenches to avoid freezing, and increased resistance to movement. This was fulfilled by using ‘self-draining’ or ‘waterproof’ designs, which included the use of impermeable layers, compartmentalised sections, and complex drainage systems, as well as surface insulation material to minimise the pipe and backfill temperature fall during the winter periods.
Safety on Sakhalin
The pipeline construction involved location-specific hazards, which needed to be managed, including:
- Crossing and working on ice, ice bridges, etc.;
- Very unstable landslide areas;
- Swamp areas;
- Pipe string instability on poor ground conditions, and particularly on slopes;
- Encounters with bears, particularly during non-noisy, survey-type activities; and,
- Encroachment into no-go areas where unexploded ordnance had not been cleared.
A ‘focused action plan’ was developed to focus attention and efforts on the four main topic areas of safety concern, which were identified as drivers, vehicles, site supervision, and subcontractor management. Each topic had a senior management sponsor and a designated leader. This approach, coupled with strict consequence management, had a positive effect on incident frequencies and severities.
The existing road traffic culture was not conducive to safe road travel. The project-specific controls comprised compulsory defensive driving tests, vehicle inspection/testing, seat-belt fixing, seat-belt wearing compliance, speed-limit compliance, and daily alcohol testing for professional drivers. A fleet of road transport monitors was used to control speeding, alcohol misuse, and other offences.
Low temperatures and deep snow were managed via thermal clothing, warm shelters, journey management rules in relation to travelling alone, and emergency survival kits in vehicles.
An additional safety hazard on Sakhalin Island was the significant occurrence of unexploded ordnance remaining from World War II. This affected most of the onshore pipeline route, particularly in the southern half of the island. A specialised contractor, in combination with the Russian military, cleared huge areas of pipeline right-of-way, station areas, and camp/storage sites.
Preserving the environment
There were several important environmental challenges in relation to both flora and fauna. Offshore, the main environmental consideration was the western grey whale. Some major re-scheduling and re-routeing of the pipeline was necessary to avoid any potential impact on the whales, as monitored by international experts on the Western Grey Whale Advisory Panel. Re-routeing around the main whale feeding areas was required, as was maintaining low noise levels from all vessels and work activities in the vicinity of the feeding areas.
Onshore, the route passes along the outer part of two nature-reserve areas and these required special pipeline construction techniques and treatment of the flora. In addition, a rare species of orchid along some parts of the route was protected from damage.
The onshore environmental challenges to fauna concerned the following:
- The Stellar’s sea eagle – protection of nesting sites and the control of noise levels during the breeding season;
- Migrating reindeer – migration routes were kept open to avoid affecting the migration patterns;
- Salmon spawning – hundreds of sensitive salmon rivers were crossed in restricted time periods to minimise impact on the spawning grounds; and,
- Sakhalin dunlin, Aleutian tern and Spotted greenshank – protective measures were necessary to avoid disruption to nesting habitats during certain periods of the year.
More than 100 cultural heritage sites were identified along the pipeline route, and these were either bypassed by a re-route or protected from the main construction activities until archaeological excavations and studies had been completed. This resulted in more than 30,000 archaeological finds, many of them crucial for understanding the prehistoric age.
