P.2 ~ New venture offers step change in reservoir recovery

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Offshore: What are the key challenges and issues facing the subsea industry and how are subsea processing solutions addressing these challenges?

Garding: Since its beginning, the subsea industry has continuously been moving into more challenging areas, stretching the boundaries of available technology. Not only does water depth continue to increase, but the produced fluids are becoming more challenging, as are the reservoir conditions with combinations of high pressure and high temperature, and possibly even lower productivities. As a consequence of these factors, the development solutions and base investments tend to become ever more complex and costly. Over the last decade, the cost of subsea developments has exhibited an upward trend, and the lifting cost per barrel is revealing a potentially non-sustainable trend.

The subsea industry as a whole, operators and contractors, is currently engaged in a large number of initiatives to address these issues. Standardization, reuse of existing designs, rationalization of project execution, and more efficient engineering and manufacturing processes are just some of what everybody in the industry is looking into. OneSubsea is no exception, and we are convinced that there is a large potential for improvement in all of these areas. We are also 100% convinced that the only way to overcome these current challenges is through the active use of technology. The industry has a need to reduce costs, but much more importantly we need to increase the recovery rates of old and new oil and gas fields around the world, i.e., get much more return on the invested capital. Increasing the oil recovery rate by about 10% from a field without any significant additional investment in the infrastructure will significantly reduce the average lift cost per barrel over the life of the field.

Many technologies and sciences have a role to play in this, but experience has shown that one of the most effective and easily adaptable methods could be subsea multi-phase boosting. This technology reduces the backpressure on the reservoir and adds energy to the well stream, thereby allowing more of the hydrocarbon to be produced to the surface. With increasing water depth, reservoir depth and tieback distance combined with heavier fluids, this becomes even more effective, resulting in an even higher relative impact on the production and ultimate recovery.

Offshore: What are the key issues with regard to wet gas and multi-phase fluid compression?

Garding: The wet gas multi-phase compressor serves the same function for a gas field as the multi-phase pump does for an oilfield; it is primarily a tool to improve or increase the production and recovery rates. Due to the market mechanisms for gas and the nature of the produced fluid, the potential for long and ultra-long tiebacks directly to shore becomes feasible.

Wet gas compression offers a very compact and robust solution for unprocessed gas compression subsea. The OneSubsea Multiphase Wet Gas Compressor, or multi-phase compressor as we call it, is capable of operating in an envelope of 100% liquid and 100% gas even though optimization is for 0–5% liquid by volume. This capability is what enables a very compact and cost-effective subsea infrastructure. The multi-phase compressor has a lot of common components with our range of very successful multi-phase pumps, and is designed from scratch for subsea applications without marinization of topsides technology. This allows OneSubsea to design for easy installation and intervention using light vessels, the latter being of extreme importance for system uptime. The delivery of gas is often executed on fixed contracts, either as feed for a liquefied natural gas (LNG) plant or trunk line sales, making the aspect of uptime even more important for gas compression than for our highly reliable multi-phase pumps.

Offshore: How do you see the evolution of subsea processing progressing, including separation?

Garding: Subsea separation, to date, has only been applied in a handful of experimental applications and one commercial application, the Total Pazflor project in Angola. OneSubsea, incidentally, has been involved in all of these systems, having supplied the rotating machinery for all of these—subsea multi-phase pumps and high-pressure pumps for reinjection of the separated produced water.

Subsea separation may have a role to play in the debottlenecking of brownfields. It enables tie back of high water cut satellites to mature field centers, which may already be maxed out on water production. It also allows the ability to cope with flow assurance issues, like hydrate prevention and high back pressure on deepwater tiebacks due to high water cut. Certain combinations of extreme oil qualities and gas production could also benefit from subsea processing or separation.

In the interest of minimizing installation and equipment costs, especially when applied in deepwater, we are confident that modular and compact systems will be required; in subsea separation, there is no one size that fits all. Therefore, our strategy is to qualify compact technologies from our parent companies, both of which have considerable experience in this area either as a user or as a leading supplier of topsides separation systems, or from third parties offering a special technical solution.

OneSubsea is equipped with a strong portfolio of proven separation components and modules, including advanced rotating machinery and high-reliability control systems from our expert environment in Celle and Bergen. We are confident that we will be able to offer a unique solution for any challenge presented before us.

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