NAUTILUS is a subsea 1.3 MW electrical multiphase pumping unit which operates an helicoaxial multiphase pump with a high speed, directly coupled induction motor fed from an offshore platform mounted voltage inverter through a submarine three phase cable.

The system operability and reliability demonstration up to 50 km was carried out under submerged conditions on an hydrocarbon multiphase loop.

This new technology available to-day can play a key role in offshore production due to the economical impact on deep water and satellite field developments; it can also substantially increase the potential of exploitable reserves.

This paper will present the technical results of the development and the advantages of this technology in subsea fields development.


A subsea boosting system can grant access to marginal or satellite offshore fields. This is especially the a satellite well located within 50 km from its case when a deep water production support on site is not cost effective when compared to direct export to ‘mother’ production platform. a shallow water platform or directly to shore.

Typical reservoir parameters for the application of a NAUTILUS multiphase booster station are indicated below: OBJECTIVE AND CHALLENGE NAUTILUS has been designed for installation on - Gas oil ratio (GOR) at standard conditions, 300 to - Gas liquid ratio (GLR) at pump suction, 2 to - Pump suction pressure, 150 to 725 psi - Pump discharge pressure, 725 to 1450 psi - Total flow at suction, 50 O00 to 200 O00 bbl/d Multiphase production represents an economically attractive solution when the wells are eruptive at the sea bottom: subsea multiphase pumping can significantly boost well productivity and substantially increase the potential of exploitable reserves.

This is generally the case when the following reservoir and process conditions are met: - Lack of energy due to low GOR, - High water depth, - Long distance to final production facilities (high back pressure at the well-head), - Increasing or high water-cut.

Used as an early production system, NAUTILUS can delay and/or facilitate the decision to implement a full development and reduce the time lag between the reservoir discovery and the first oil production. 1400 scft/bbl 12 vol/vol The objective of the NAUTILUS Project is to design, build and evaluate a subsea multiphase electric booster system to demonstrate its operability and reliability.

The challenges were the development of a subsea multiphase boosting system for variable speed over long distances (50 km) and the development of key components required for the electrical power transmission with its associated control and communication system.

THE NAUTILUS CONCEPT Boosted by a subsea helico-

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