Subsea heading further, deeper, colder

At a recent Bergen conference showcasing the strength in depth of Norway's subsea industry, Statoil EVP Øystein Michelsen challenged delegates to work with his company in developing the technology to go further, deeper and colder and seize the great opportunities ahead for operators and suppliers alike. David Morgan listened in.

Addressing the Underwater Technology Conference (UTC) dubbed the world's oldest subsea conference in June, Øystein Michelsen, Statoil EVP development & production Norway, expressed his amazement at how much the Norwegian subsea industry had achieved in a relatively short space of time since the early days of Troll Oil and Asgard and subsequently in handling Kristin's record reservoir temperatures and pressures. Today about 50% of Statoil's production comes from subsea wells.

The subsea journey is something we are really proud of in Statoil. It's no more than 25 years since the subsea adventure started, he said, and this work is of great interest to stakeholders all around us because technology creates value. Michelsen emphasized that subsea technology remains one of the main focus areas in an updated Statoil corporate strategy that is seeking to achieve a production target of 2.5 million barrels a day by 2020.

Contractors panel members (left to right) Knut Boe (Technip), Herve Valla (Aker Solutions), Ottar Vikingstad (Emerson/Roxar) and Charles Davison (Oceaneering) fielding questions. Also on the panel were Werner Menz (Cameron), Ove Boe (Siemens) and Ole Torvanger (NLI)

Statoil is currently in the thick of maturing three groundbreaking projects focusing on subsea gas compression, described by Michelsen as the next big step for our industry. As well as collaborating with Norske Shell in ongoing Ormen Lange compression pilot studies, Statoil has taken the lead at its Ãsgard gas and condensate field in what is tipped to become the world's first subsea gas compression reality (OE April). With Aker Solutions serving as the project's lead contractor and MAN Turbo & Diesel supplying the compressors, this NKr15 billion investment is expected to improve recovery rates at Ãsgard's two subsea satellites, Midgard and Mikkel, from 60% to 86% and 60% to 69%, respectively. World class, Michelsen declared.

OE contributing editor Terry Knott served as UTC conference moderator.

Subsea gas compression is an important technology leap when it comes to increasing the recovery rate and the lifetime of a gas field, he explained. The third such project Statoil has on the go, in partnership with Petoro, is the subsea wet gas compression plant destined for Gullfaks South, a satellite linked to the Gullfaks C platform. Here Framo Engineering – expected to be rebranded Schlumberger Subsea before long is handling design and construction.

Karl Johnny Hersvik, Statoil SVP research & development and deputy chair of OG21, with Bergen's mayor Trude Drevland.

This is one of our most exciting projects, noted Michelsen. The introduction of subsea wet gas compression will increase recovery from the Gullfaks South Brent reservoir by 22 million boe, corresponding to a 4% increase in the expected recovery rate. And the recovery rate can be increased from 62% to 74% on Gullfaks C with this solution combined with conventional low pressure production in a later phase, which is very good for a subsea field.

Intecsea's Ian Ball in reflective mood during the UTC icebreaker.

This is pioneering work, he added. It is a springboard to the future and seabed wet gas compression for Gullfaks South is a typical solution for small and mid-sized fields and there are many of them due to the size of the compressor. This is the first step in a long journey. The concept is flexible and can be used in both new and existing fields. Statoil has already identified several candidates for wet gas compression.

Subsea wet gas pre-compression can contribute to maintaining high gas production on Gullfaks C when the reservoir pressure drops below critical level. At the same time the process can boost gas recovery from the Gullfaks South Brent reservoir by providing additional compression power. The gas will be compressed on the seabed, raising the pressure in the pipelines, speeding up gas flow to the Gullfaks C platform.

Subsea gas compression is an important technology leap. Ãystein Michelsen, Statoil

Norway's first spar

Deepwater production from the Norwegian Sea came another step closer to realisation in January with Statoil's decision that its Ãsta Hansteen (previously Luva) field would be developed with subsea wells connected to a spar platform Norway's first and the world's biggest to date. A Technip/Hyundai consortium beat Aker Solutions to the spar contract last month. Statoil has a 75% interest in the field and anticipates startup in 2016.

Describing the project as a real challenge, Michelsen observed: This will be the northern-most field development in the Norwegian Sea and it's located away from existing infrastructure in water depths of approximately 1300m. It would, he added, be the engine for production from the area's deeper waters, enabling the tie-in of other discoveries, but profitability would be one of the project's challenges given the need for costly new infrastructure.

Turning his attention to last year's much-trumpeted major discoveries on the Norwegian continental shelf, he said the huge Johan Sverdrup find only 140km west of Stavanger and with a production horizon of 50 years will be one of the main undertakings on the NCS in the years ahead and create a new processing and transportation hub on a level with Norway's other offshore giants. The owners of the two licences involved will cooperate in its planning with Statoil, which has a 40% interest in both, serving as operator in the first phase and responsible for submitting the PDO for the standalone development.

We have worked on many solutions for the development of Johan Sverdrup and the field most likely may consist of both platform wells and subsea installations, said Michelsen.

Another recent discovery, Skrugard and Havis, opens the door to another new core area Statoil is banking on to reach its ambitious 2020 targets. Located in a little explored area of the Barents Sea, the combined field has estimated recoverable volumes in the 300-600 million boe range and with a potential upside. This is a substantial discovery that makes a new cluster possible, noted Michelsen. With a water depth of about 350m, it is an obvious candidate for a floater and subsea installation.

Due for completion around 2015, the NKr3 billion Gullfaks South plant will have two 5MW Framo wet gas compressors installed on a subsea template in 135m of water and tied in to existing Gullfaks C templates and pipelines 15km away.

All these stages on our subsea journey have opened up new possibilities, Michelsen concluded. As a result we see possibilities to develop resources located in challenging areas that no-one would have dreamt about developing 20 years ago.

The future of the NCS is bright, with a lot of opportunities and high activity levels but it is of key importance that we succeed in the collaboration between the supply industry and the operators, he told UTC delegates. But we have high expectations, he said, adding that for the full potential of the NCS to be exploited suppliers needed to deliver on time, on cost and not least to the agreed quality.

We experience increased downtime to which subsea is a great contributor, said Michelsen. We need to work together to get rid of bottlenecks and quality costs; also lead times are an issue that needs to be addressed. There is a need to bring costs down, to find more cost-effective subsea solutions. We must work together to enhance efficiency and standardisation to make your processes more streamlined and to make the machinery run smoothly. This is a challenge that we have to address together. OE