Schlumberger - new subsea landing string electrohydraulic operating system
Feature Articles, Nov  27  2009 (Digital Energy Journal)

- Schlumberger has launched a new subsea landing string electrohydraulic operating system called SenTURIAN*, which is used during completion installation and well testing operations.

SenTURIAN is a key component of the subsea landing string and is deployed during operations performed from a dynamically positioned vessel. The system provides verification of installed equipment functionality and enables fast acting well control in the event of an emergency situation.

Schlumberger engineers preparing the SenTURIAN electrohydraulic operating system for a deepwater completion operation

The compact design of SenTURIAN makes it easy to handle and operate, and the small diameter umbilical allows for safer and faster deployment. The overall configuration enables efficient operations and results in valuable rig time savings.

The innovative design incorporates pressure balanced accumulators which are more efficient and shorter than conventional designs. This reduced length allows for the accumulators and solenoid valve manifolds to be incorporated in one single unit.

Electrical signals are sent from the surface to operate the solenoid valves and allow the stored hydraulic pressure to be transferred from the accumulators to the desired subsea or downhole function.

It is compatible with all Schlumberger SenTREE* subsea test trees, third party tubing hanger running tools, and downhole equipment.

SenTURIAN can send and receive data from the surface, so it can provide instructions and send back telemetry feedback from subsea and downhole equipment.

The standard configuration is capable of operating in water depths up to 15,000 feet (4,572m) and pressures up to 15,000psi. The systems modularity allows for upgrade to meet project specific requirements.

Schlumberger claims that it is the first and only in-riser electrohydraulic operating system that is designed and certified in accordance with the International Electrotechnical Commission's IEC 61508 SIL 2 reliability specifications for safety-related systems, certified by TüV Rheinland. Its design enables compliance with ISO 13628-7 standards by providing electronic redundancy and telemetry feedback.

SenTURIAN was used in the first deepwater well completed offshore India, then subsequently on a total of 29 completions in India and the Gulf of Mexico. This includes four jobs in a high pressure environment.

If there is ever a need to disconnect the landing string (eg because of a storm), it can close all the subsea test tree valves and disconnect the landing string in under 15 seconds safely, following a pre-determined sequence of operations.

*Mark of Schlumberger

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