Drillling platform in icy sea

Drilling for oil and gas in the Arctic Sea

Huge platforms in the Arctic waters off Russia's east coast are defying the elements to produce vast amounts of valuable oil and gas as E&T reports.

Sakhalin is a large, inhospitable elongated island, sitting just off the eastern coast of Russia in the north Pacific. Until recently it was best known as the location of the infamous shooting down of Korean Air flight 007 on 1 September 1983 by the Soviet Union, who claimed it was a US spy plane.

More recently it has gained prominence as the home to one of the most ambitious offshore oil and gas projects to date. Three huge fields just north of the island are producing vast amounts of raw materials in some of the most challenging conditions imaginable.

The exploration and production offshore of Sakhalin is managed by Sakhalin Energy, a consortium of Gazprom, Shell, Mitsui and Mitsubishi. The company was set up 15 years ago to manage the field. The first resources came from Sakhalin I, which started producing in 1999. The oil and gas was stored at the drilling platform and collected by tankers. However, because of the frozen conditions it was only able to operate for six months each year, and therefore the decision was made to construct an 800km pipeline to the nearest year-round accessible port at Aniva Bay, on the south side of the island.

The island itself is about one-third the size of the UK, with a population of just over half a million, the majority living on the relatively temperate south of the island. The southern port of Aniva Bay is the only accessible part of the island to remain ice free throughout the year, even though in winter months temperatures plummet to -35C.

Travelling to the island is no mean feat; from western Europe it is an eight-hour flight across the sprawling country. When you disembark the Aeroflot Boeing 767 at Yuzhno-Sakhalinsk airport you are immediately struck by the barren, inhospitable nature of the island; rugged landscape of hills and streams all masked by a generous sprinkling of snow and ice. A somewhat perilous drive south, through snow-cleared streets brings you to the heart of the island, Aniva Bay.

The first thing that grabs your attention when you reach the port is the huge LNG terminal and the oil export terminal part of the Sakhalin II project, but the real story begins much further north, about 800km north, where the oil and gas reservoirs lie.

Sakhalin II is a monumental feat of engineering. It operates amid some of the world's harshest conditions in Russia's far east, an area prone to earthquakes. The project on Sakhalin Island exports LNG and oil to the fast-growing energy markets in the Asia-Pacific region and the west coast of North America. It will meet nearly 8 per cent of Japan's gas needs and 5 per cent of South Korea's.

'This is one of the biggest, most exciting and therefore most challenging projects in the world,' Rob Ryan, technical director Sakhalin Energy, says. 'It is unique in so many ways. We are in an Arctic environment, and a pristine Arctic offshore environment at that. Never before has anyone tried to do something so big in such a challenging offshore environment.

'Before coming here I worked in Alaska and even there we have never put platforms offshore and operated them in the same way with production and drilling that we are now doing here.'

The platforms that produce Russia's first offshore oil and gas, 15km from the Island, stand in water up to 50m deep in the stormy Sea of Okhotsk. They are the Piltun-Astokhskoye A platform, Piltun-Astokhskoye B and Lunskoye A platforms.

In this region, temperatures can drop to -45C in winter. Arctic winds combine with high humidity for a wind-chill factor of -70C. At such temperatures, people can work outside only in short shifts despite steel cladding on the outer sides of the platforms that breaks the wind, offering some protection.

'These reservoirs are not particularly unusual, apart from their size,' Ian Craig, chief executive Sakhalin Energy explains. 'They have about four billion barrels of oil equivalent. But they are off the north east of the island, and in that area we have sea ice - moving sea ice - for about six months of the year and that poses a real challenge for development.

'We have three oil and gas platforms in that vicinity and each of these has to resist the loads from the moving ice and from seismic events that also occur in that area, and they form the base for drilling the wells, which include the largest gas wells in Russia. But that sea ice movement prevents us from having normal oil and gas activities using tankers, it's just not possible, so we decided to have the export point here on the south of the island.'

Ryan takes up the tale. 'On Lunskoye we are drilling gas wells - the biggest gas wells in the world,' he continues. 'We are producing from two of the gas wells at well over 300 million cubic feet of gas a day and expect to be able to go up to at least 350 million.'

Huge scale

In terms of volume that is enough gas to fire a 2GW power plant. 'Those wells therefore are absolutely huge; we complete them with nine and five-eighths tubing, that's why we need such massive equipment to drill them.

'Over on Piltun we have an oil development - extremely challenging there for different reasons. One is because of the extremely technical challenges of the directional drilling requirements for that field.' The directional drilling challenges come from the fact that the platform is moved seasonally to avoid the feeding grounds for the western grey whale.

One thing that is hard to convey is the sheer size of the structures involved. 'When you first come in and you're flying from Nogliki and the helicopter's approaching the platform, the first impression is just how enormous they are,' Ryan says. 'You can look at them in a picture, and you have no idea until you see a massive vessel tied up alongside that looks like a small skip or row boat and you realise just how enormous these are.

'They are producing platforms as well as full-time drilling platforms. We have many months of ice and when you first land and step on to the platform, you're just getting over the shaking of the helicopter then you start to feel the vibration of the ice which is moving around you and when you look down off the side of the platform you can see that flow of ice, that constant movement, usually several knots of current dragging that ice along. You can see it parting as it moves past the gravity-based structure, the legs of the platform.'

Ice poses serious technical challenges too. From December to May, a thick layer of ice surrounds the platforms, preventing tankers from reaching them to load oil and gas. Instead, a 300km network of underwater pipelines takes the hydrocarbons ashore year-round.

Ridges of compressed ice can carve deep gashes in the seabed and could damage pipelines. A thick concrete coating protects them, however, and they are buried five metres beneath the seabed wherever the sea is less than 30m deep. As an extra safeguard, electronic leak-detection systems including valves halt the flow of oil and gas if the pressure drops.

Once the hydrocarbons are pumped ashore, a processing plant treats gas and condensate, a natural gas liquid, from the Lunskoye-A platform, along with oil and some gas produced by the Molikpaq and Piltun Astokhskoye-B platforms. From there, the gas is sent through two parallel 800km pipelines to the Prigorodnoye complex at Aniva Bay, which includes an LNG plant, an oil export terminal and a port which is virtually ice-free during winter.

Environmental concerns

The pipelines cross seismic faultlines at 19 places and more than 1,000 of Sakhalin Island's 60,000 rivers and streams. The 8,000 construction workers who built them could only start work after unexploded munitions from the Second World War had been cleared.

Engineers planned the onshore pipeline route to avoid most of the active faults where even low levels of seismic activity could cause ruptures. If no alternative route existed, they used pipeline segments made of steel that can bend up to four metres without breaking.

The route was planned to create the least disturbance to vulnerable species, such as the Steller's sea-eagle and Siberian spruce grouse, and to the island's rich vegetation. Laying the pipelines beneath streams where salmon spawn - a highly sensitive operation - took place in winter when the water was frozen.

'The pipelines themselves have many characteristics that are different from any other part of the project,' Jaap Guyt, pipeline project manager, Sakhalin Energy adds. 'They extend over an enormous amount of countryside and they involve 500,000t of steel that has been installed below ground. We have had to cross 1,100 water courses. Some of these have taken us some time to finish but most are done during the winter because then the water in the rivers is at its lowest level and so it is easier to construct a river crossing.'

The gas arrives at Prigorodnoye port after a day-long journey from the platforms. There Sakhalin Energy has built Russia's first LNG plant, designed to produce 9.6 million tonnes a year of LNG. That is enough to generate electricity for around 24 million European homes. Almost all the production capacity is committed in long-term contracts to supply customers in Japan, Korea and North America.

'The oil and gas goes from the platform through subsea flow lines below the depth of ice scour onshore where it goes through a processing facility,' Craig explains. 'The condensate is stripped out from the gas and the condensate is mixed with the oil. The oil goes down a 24in oil pipeline; the gas goes down a 48in gas line. To give you an idea of the scale of the pipeline system, if we were in the UK, this is the equivalent of having the platforms just off the shore of Aberdeen, the onshore pipeline starting in Dundee and the LNG terminal in London.

'The oil goes into storage tanks, two large 100 cubic metre storage tanks and then it goes to the tanker loading point out in the bay. There we load the oil tankers and they set sail for the various markets in the world. At peak production we will be producing about 150,000 barrels of oil a day and that will give us roughly 100 oil tanker movements each year.

'The gas has to be treated before we can refrigerate it. We remove any last traces of water, we also remove any CO2 and H2S because this can damage the system downstream. We then refrigerate the gas in two steps, first of all down to -50C and then -160C. This requires a lot of power, the second refrigeration alone requires about 80MW. And here we get an advantage because the colder the climate the less power you need to generate the same volume of LNG. And we can actually make more LNG in the winter than we can in the summer, and that matches the market demand, fortuitously.

'So the LNG is chilled to -160C and it shrinks in volume to 1/600th of its volume at room temperature. It is also stored in two 100-cubic metre storage tanks and then shipped in LNG carriers. Our capacity is about 9.6 million tonnes each year, which is the equivalent of about 150 ships each year. Most of these ships will be supplied by our customers. So 150 ships a year LNG, 100 oil tankers from the oil terminal itself.

'This is going to be a very busy port, one of Russia's newest ports. When you see what has been achieved here over the years it fills me with immense pride. It is a huge effort from 25,000 people here at the peak from 45 different nationalities. And on a frontier project like this you can never anticipate all the problems upfront; you have to be able to adapt and learn as you go along and that's what we've had to do here to overcome the challenges.'

Although the platform itself is fairly simple - all power comes from onshore, and there is no compression required as the reservoir pressure is sufficient to get the oil and gas to the beach - the construction and operations of the platforms and pipelines is a tremendous engineering feat. To overcome the challenges of sub-zero temperatures, ten-metre waves and a remote location is a credit to the ingenuity and commitment of all those involved.

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