The Subsea Master Station: Its Evolution And Current Applications
Authors: Leith G.J. , Anson Bernie 
Published: October 2008

The Master Control station has always been an integral part of the multiplexed, electro-hydraulic subsea control system. The development and increasing sophistication of both subsea and surface elements has kept pace with the advances in technology of the 1970's, 1980's and 1990's.

Starting from primitive beginnings, a high degree of standardisation in the hardware and software platforms for the Master station has taken place. This paper examines a range of Master station solutions available, developments in response to advances in subsea instrumentation, and likely future developments.

In the North Sea at least, this technology has now reached a stage of maturity and acceptability that makes it a standard option in oilfield development. This is therefore an appropriate time to take stock of the current situation with regard to the Subsea Master Station.

INTRODUCTION

In the UK and Norwegian sectors of the North Sea, subsea production systems are increasingly becoming the norm for small satellite developments close to existing platform and pipeline infrastructure. In addition, some form of subsea development is generally included as part of the overall production strategy for the larger new fields.

Recent trends suggest that the multiplexed electro-hydraulic control system has emerged as the clear favourite over its rivals direct hydraulic and piloted hydraulic systems. This paper examines the development and current state of one of the key elements of the multiplexed electro-hydraulic control system The Master Control station.

By their very nature, multiplexed electro-hydraulic control systems require an intelligent topside unit to perform subsea telemetry and signal processing, and to provide interfaces between the subsea equipment and the humans and other control systems involved in the production process. The evolution and development of these topside units dates back to the late 1970 ' s, when the first such unit was built in Houston by TRW. This unit was essentially a prototype, with a unique hardware configuration, and a large volume of bespoke project software. It was also a single system, with no capability for dual redundancy. This unit was eventually deployed in Shell/Esso' s Cormorant field in the North Sea to control the Underwater Manifold Centre, the world's first multiwell subsea development. At the time it was produced, this topside unit, or Master Control station, was based upon what was state-of-the-art microprocessor technology. Sincethen, the Master station has evolved rapidly as a result of developments in computer technology throughout the 1980's and into the1990's. This trend looks set to continue for the foreseeable future.

The role of the Master Control Station has also expanded rapidly in response to significant advances in computer processing power and storage capacity. As a result of the expansion in the role of the Master Station, is has become essential that dual redundant systems are available to provide the high reliability required.

In order to quantify the advances that have been made in processing power and storage capacity over the last 12 years, a simple comparison can be made of typical systems produced during the period.