In a year that saw subsea technologies attain their greatest successes to date, the double record-breaking installation of Norwegian oil and gas company Aker Solutions' (formerly Aker Kværner) MultiBooster pumps at BP's King field in the Gulf of Mexico stands as one of the most significant developments of 2007.
Described as 'a major breakthrough for Aker Solutions' subsea technology' by Svenn Ivar Fure, Aker Solutions' trees, processing and boosting senior vice president, it also marks a particular high point in the ongoing expansion of the whole sector.
Located in about 5,500ft of water, the King field installation lies nearly twice as far below the surface as the previous deepest application and at more than 15 miles from the Marlin tension leg platform (TLP) it easily beats the existing record of six miles from pump to host platform.
If all goes according to plan, the two pumps should boost production by an expected 20% and extend the field's life by another five years, providing a recovery factor increase of 7% on its yearly output of oil.
Subsea production has been teetering on the brink of realising its true commercial promise for nearly quarter of a century, and producing maintenance-free equipment designed to meet the challenges of the deep-water environment has historically formed a key technological barrier.
This, coupled with the cost of constructing and installing subsea systems, has limited uptake – though as the famous OTM / Douglas Westwood 'Game-Changer Report' made clear, the offshore landscape has gradually been changing.
The growing push to develop reserves in deeper and more remote water has given increased production and enhanced recovery added emphasis and ultimately formed one of the main factors in the recent development of subsea technologies – particularly multi-phase pumps.
Much of the successful progress of this technology derives from the uniquely Norwegian attitude to offshore research. As an oil nation of more than 30 years standing, Norway has a number of both maturing and marginal oilfields lying on its continental shelf.
Faced with a technological insufficiency, which precludes the expansion of the lifetime and productive future exploitation of these fields, the nation had to act. In 2001 the country's Petroleum and Energy Ministry set up the Oil and Gas in the 21st Century organisation (OG21) to foster technological advancement. The resulting collaboration and cooperation between research institutions, authorities and offshore companies has enabled many of the existing barriers to resource recovery to be removed.
Demo 2000 – an organisation that promotes the pilot qualification of fledgling technologies – is one of those that supports OG21's mission and played an important part in helping prove the Aker Solutions multi-phase boosting approach.
In essence, the idea behind the technology is very straight forward. As reservoir pressure drops, oil and gas production declines; by reducing the well back pressure, subsea boosting significantly improves reservoir recovery and increases the flow rate, with multi-phase pumping extending the well stream's possible transport distance.
However, though the underlying principle may be easy enough to grasp, making it into a practical reality has been less simple – Aker Solutions' MultiBoost technology having been under development since 1998. In addition, to enable the King field installation to go ahead, the special challenges posed by the project's depth and distance also called for a number of new associated techniques and approaches to be devised.
Aker Solutions first began developing subsea boosting technologies in the early 1990s. Starting with the Kværner Booster Station, with the support of the Norwegian Government 'Demo 2000 programme' and a number of major oil companies, the work ultimately gave rise to the MultiBoost system – German partner Bornemann providing the twin-screw internals for each unit.
Proving the current technology involved a four-month trial in the Lyell field in the North Sea, off the UK – the first subsea installation of a pump of its kind – the pilot being run by the field operator, CNR International. The complete MultiBooster pump solution, including topside equipment, controls, condition monitoring and a five-mile long power umbilical, was delivered in December 2005 and start-up followed in January 2006. Power was provided by subsea cable from the Ninian North platform while the well fluids were transported to Ninian South.
The design concept has several key benefits, which the trial was to showcase successfully under operational conditions, not least amongst these being the system's wide performance envelope and high-pressure boost at high gas content when handling multiphase flow. Each unit's Bornemann twin-screw pump has a 68,000bpd capacity and is rated to 5,000psi and in addition, the pump system is modular making subsea installation and retrieval easier.
As a non-profit contract for Aker Kvaerner, funded and supported by Demo 2000 and project partners CNR, ENI, Hydro, Shell, Statoil and Total, the Lyell project firmly established the efficacy of the system, which was to win OTC Spotlight on Technology and ONS innovation awards in 2006.
As John Allen, the project manager for CNR in Aberdeen, commented in May 2006, the subsea booster had 'exceeded expectations in terms of production capacity and performance'.
KING FIELD AND BEYOND
Located in Mississippi Canyon blocks 84, 85, 128 and 129, in over 5,000ft of water, the King field is one of three fields producing from the Marlin TLP and accounts for over 50% of its production.
The two subsea pumps and associated equipment installed – which began first production in December 2007 – represent a major milestone in the application of a technology which holds the potential to revolutionise resource recovery from deepwater offshore fields.
However, attempting to more than double the depth and distance records for this kind of application inevitably brought its own additional problems, calling for a number of new, ancillary technologies and techniques to be developed especially for the project.
To overcome weight and cost factors, the Nexans-supplied umbilicals required to link the control platform to the pumps – some 15 miles distant – were designed as self-contained delivery lines for lubrication oil, hydraulic fluids and chemical feeds. In addition, they also house novel fibre-optic communication cabling to guarantee fast response times to changes in lubricant pressure and pump speed.
The installation also needed a high-voltage distribution system with the capability to control multiple variable-speed drives at long distance – avoiding interference across the umbilicals and enhancing reliability by enabling simplified 12kV remotely operated vehicle (ROV) connectors to be used.
As the world's first subsea multi-phase pump application deeper than 3,000ft, it is not only BP who will be taking a careful interest in the outcome. Although the technology has obvious synergy with fields in the Gulf of Mexico and West Africa, the ability of subsea multiphase boosting to bring about increased oil recovery and extend production lifetime has clear resonance for the whole offshore industry.
With a backdrop of rising oil prices, the quest for enhanced recovery and increased commercial viability has changed the drivers on subsea processing from technological necessity and financial incentive to meeting the demands made by deeper and more remote reservoirs.
Amid widespread agreement that both the development of new fields and the continued exploitation of mature offshore resources will largely hinge on improved production systems, the way lies open for proven booster technologies to truly begin to change the game.
In the words of Raymond Carlsen, executive vice president Aker Solutions Subsea, the technology 'has the potential to enhance production from new developments and producing fields worldwide, in both shallow and deepwater applications'. Breaking two industry world records 5,000ft beneath the Gulf of Mexico seems a pretty good start.