Statoil takes the upstream plunge in Norway
Norway has a rich history of technological innovation, especially in the upstream sector. And now the country’s flagship producer Statoil is leading the offshore industry’s shift to the sea floor
The lift doors close with a heavy, echoing thunk. The lift mechanism jerks sharply as it begins a juddering journey downwards. It takes almost nine minutes to travel 303 metres from Troll A’s topside to the seabed. The platforms slip-formed concrete shaft – one of four – houses the risers which carry Troll’s gas to surface. In the yellow light, the only sound is the soft whoosh of fluids travelling upwards from the reservoir through the risers. It is warm; the reservoir fluids still hold heat from deep within the earth. A thin shell of concrete – just 1.5 metres thick – keeps the North Sea at bay.
In 1996, the platform made history. When it was towed from shore to the Troll field, 100 km offshore Bergen, the 472-metre high concrete gravity-based platform became the largest structure ever moved across the surface of the earth. The field came on stream in 1997, and the technology developed to tap the 1.309 trillion cubic metres of gas in Troll’s reservoir was cutting edge.
The concrete gravity-based platform was one of the Norwegian offshore industry’s first major innovations; Troll A is the design’s apogee. Developed in the 1970s to meet the demands of the North Sea, the platform design was tougher, heavier and larger than a steel frame jacket, then the virtual default solution for offshore developments.
Today, however, offshore discoveries – even one of Troll’s magnitude (it holds roughly 60% of Norway’s total gas reserves) – are rarely brought into production via a topsides solution alone. In the almost 15 years since first gas at Troll, much of the technology that enabled the reservoir to be tapped has been refined, modified, expanded – and shifted to the sea floor.
Norway has been an innovator in the industry’s move to the seabed. Statoil, Troll’s operator, has been at the forefront of this push. For Karl Johnny Hersvik, the company’s head of research, development and innovation (RDI), furthering Statoil’s technological capabilities is vital, not least because more than 50% of the company’s total production comes from subsea developments. "The business environment is changing, and changing rapidly," he said in a post on the company’s Innovate blog. "The technological challenges are becoming more complex."
But, he told Petroleum Economist in an interview, while the Norwegian Continental Shelf (NCS) can throw up unique problems, the solutions often have a wider application. "We are really lucky," he said. "A lot of what we do on the NCS is fit for purpose in other areas. There are an enormous number of examples where the NCS has presented challenges, and the solutions are now being used elsewhere.
"One example is at Troll. That is where we discovered multilateral drilling. It was technically very difficult, but now it has been adopted internationally." The technique, which involves drilling a main bore, then multiple lateral wells branching off from that at precise intervals, was developed to tap Troll’s two thin oil zones, once thought impossible to produce. In 2011, Troll’s total production was 568,450 barrels of oil equivalent a day, about 15% of Norway’s total output of 2.3m barrels a day.
Hersvik adds: "Subsea separation is another example. We first used it at Troll, then at Tordis and Vigdis. Now the technology is being taken even further by Petrobras at the Marlim field (offshore Brazil)."
Hersvik’s unit does not focus solely on subsea technology. At present, the 767-strong core R&D team is working on more than 290 projects, at various stages of development. Their work covers drilling technologies, improved and enhanced oil recovery research, as well as work on a number of seismic and geophysical applications.
But for now, many in the industry are eagerly watching Statoil’s work pioneering subsea gas compression at Åsgard, in the Haltenbanken area, offshore Trondheim. The project aims to compensate for an expected drop in pressure from the Midgard and Mikkel fields – two subsea field developments tied back about 50kms to the Åsgard B platform. By 2014, Statoil believes the fields’ reservoir pressures will be too low to carry output to Åsgard B. Rather than build a new platform with conventional surface compression units, and carry the costs this would incur, Statoil opted to move gas compression to the seafloor.
Higher efficiency, lower cost
A subsea solution, Statoil says, will be both cheaper and more efficient. As well as extending the field’s life, the project should add around 28bn cm of gas and 14m barrels of condensate to Åsgard’s reserves. The module is set to start operations in 2015, and, as Hersvik points out, will be the culmination of almost 20 years’ work. "There is no typical timeframe from idea to first commercial iteration," he said. "The average might be around four years, but the work on subsea compression first started in 1997."
The Åsgard subsea gas compression project is a vital step for the offshore industry, making the possibility of a full-field subsea development closer to reality. Hersvik is confident that such a development will happen – and soon.
"I am absolutely confident it will happen," he said. "With the right field, the right find, we should be able to do this by 2020. Look at what we are doing at Åsgard, with our current technological capabilities. We have tangible projects ongoing that will help us close the technological gaps. We know how to separate fluids from gas; oil from fluids; we are running three compression projects; we are working hard on long-distance, multiphase transport, and on how to get power to offshore installations."
When Troll came on stream, the concept of shifting topsides operations to the seabed was, for the most part, simply that. An idea. Now, however, that idea is close to reality. "That’s the whole point of R&D," Hersvik said. "It’s evolutionary. You modify expectations and approaches for a specific field. You need to approach technology as if it were an organism. It’s always growing, always changing.
"That’s definitely part of the fun. But it is also a major part of the challenge."