Introduction to New Technology Applications, Data Acquisition Capabilities, and Features of the All-Electric Boosting Control System
Authors: Bergtun Kjetil , Mahler Carsten , Melheim Trond 
Published: April 2022

Section 1: Abstract

This paper will explain what an All-Electric System (AES) is, how it fits within a subsea application and how it compares to the traditional Electro-Hydraulic System. It explains how implementing this system will simplify operating processes, reduce both topside and subsea weight, reduce cost, and lower the risk of hazardous fluids escaping into the ocean. The Vigdis Booster Station (VBS) project started back in 2017. Technical requirements demanded an AES.

The concept of using an AES in subsea applications is not new. Development and operation have been underway since the early 2000's, primarily for subsea production system which pioneered this technological development.

The VBS is the first AES for a Subsea Processing System. A multi-phase pump boosts production from the Vigdis field to the Snorre A platform. The pump is controlled from the Snorre B platform through an 18 km combined power and control umbilical. The VBS started production early 2021.

The main difference between an AES and a traditional electro-hydraulic system is that it replaces hydraulic fluid with electric power as the energy source for the Subsea Control System. This leads to reduced complexity and carbon footprint: Eliminates a costly and heavy Control Fluid (CF) hydraulic power unit (HPU)Saves topside tubing down to umbilical hang-offEliminates the need for control fluid tubes in umbilical or CF jumpers subseaEliminates the need for a large and heavy subsea hydraulic actuatorEliminates the need for subsea accumulators for control fluid.Eliminates the need for any sea-chestsMakes it possible to have all actuators individually retrievable and interchangeable.

It also avoids pressurized control fluids and the associated hazards connected with them; and prevents sea pollution from the exhaust control fluid.

Besides eliminating these downsides of a traditional electro-hydraulic system, implementing an electric control system comes with various inherent technological features such as: Simplified system testingMore precise, system-conserving valve operationsImproved diagnostic capabilities and system health monitoringEnhanced data evaluation, e.g. predictive maintenance

The VBS includes eight off actuated process valves and small-bore valves, of which six valves range from 10" to 12" with a retrievable torque intensifier on the valve's class 7 interface. The electric actuators (eActuators) provide valve operation through standard class 4 interfaces.

The electric subsea control module (eSCM) is mounted on a retrievable pump module with a dedicated installation funnel. This leads to a flexible system where eSCM, actuators and jumpers are all individually retrievable.

This paper focuses on the All-Electric Boosting Station design. Special focus is put on the electrical actuators that were introduced in this project as well as the challenges to master during project execution.

It will highlight new data acquisition capabilities and give an outlook on features that provide additional value to the boosting station operator.