STAVANGER, Norway – Siemens and Statoil have developed and qualified a subsea hydraulic power unit (SHPU) designed to provide hydraulic power at the offshore well site.
The SHPU supplies low-pressure and high-pressure control fluid to the subsea control module that operates the hydraulic valves, downhole safety, valve and downhole chock/sliding sleeve.
It can be used if the umbilical fails and also as an alternative to the hydraulic lines in the umbilical.
Siemens adds that the power unit has passed function tests under hyperbaric pressure equal to a water depth of 500 m (1,640 ft).
Originally, the SHPU was developed for contingency use in the event of an umbilical failure on a field in the North Sea. Now Siemens foresees further applications, including extend the life-time of brownfield facilities, and a more cost-efficient alternative to complex umbilicals on greenfield developments, especially those in deepwater or involving long step-outs.
The technology’s main advantage, the company claims, will be to replace hydraulic power transmission lines with local subsea hydraulic power generation and storage.
In addition, it removes issues associated with hydraulic friction losses in umbilical lines and can lead to reduced topsides requirements in terms of space and weight capacity.
The SHPU has standardized interfaces, and is designed to be subordinate to the local subsea control module, connected via an SIIS level 2 or SIIS Level 3 interface.
It takes auxiliary electrical power from existing infrastructure at the well site, then supplies hydraulic power required for operation of the well valves. This way, Siemens says the hydraulic system can achieve faster response and less energy consumption.
During operation, the unit does not require any changes to the well’s emergency shutdown strategy, and it can be adapted to all conventional hydraulic interfaces. It is designed for single lift installation with ROV assistance.