The control system for the Central Cormorant Underwater Manifold Centre (UMC) is an important step forward in developing the technology of subsea production. It provides reliable, fast operation of over 250 UMC valves and sensors at a distance of 7 kilometres.

Included in the paper is an overview of the complete control system with selected components described in more detail. Principal guidelines which shaped the final design configuration are also discussed and problems encountered during design and manufactures are highlighted.

The paper stresses the thorough testing that was an essential requirement prior to installation. Finally, general conclusions are drawn about the approach taken which would be of benefit to similar projects in the future.


The Central Cormorant UMC is operated from Cormorant 'A' platform by means of an electro-hydraulic control system. Primary operations provided by this system are:

  • Valve operations for the UMC manifold, Xmas trees, chemical injection system, and downhole safety valves.

  • Data monitoring of the UMC manifold and wellhead pressures, and hydrocarbon sensors.

  • Shut-down actions, automatic or 'on command'.

Fulfilling the scope of these control functions for the complex UMC - there are more than 250 valves and sensors for example - has resulted in the most extensive application to date of subsea control techniques. Recognition of this made the project team especially aware that it would be essential to generate and maintain the highest level of confidence in the system's performance. Plans were therefore made to achieve this through detailed development and testing of the system and its individual components.

The control system had to satisfy the constraints of safety, reliability, flexibility, and ease of maintenance which are common to all aspects of the UMC project. Initially, the controls' design group drew on experience gained from Exxon's SPS project. However, it was soon apparent that extensions and modifications would be necessary to meet demands of the UMC's particular requirements.

The objectives of this paper are:

  1. to give an overall description of the control system, highlighting the considerations that shaped its design,

  2. to describe selected components in more detail, and the problems encountered in their development, and

  3. to explain aspects of the landtest programme for the control system which verified it would provide safe and effective operation of the UMC.


The UMC control system contains a closed-loop hydraulic network for operation of subsea valves and other equipment, and an electrical power and communication system that activates and controls the hydraulic network. The communications system is multiplexed and also provides facilities for feedback to the control panel on the platform of operational data from the UMC.

The choice of an electro-hydraulic system was based principally on speed of response required for safe, reliable operation. Valve functions must be fast enough to ensure the UMC can be shutdown rapidly and permit normal operating tasks (Through Flowline (TFL) Tools servicing for example), to be carried out efficiently.

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