The Subsea Intervention System has been designed by CIE Well Control Limited to meet the intervention requirements of, and is compatible with a large number of existing wellhead systems, as well as meeting the intervention needs of the operator community. The system, acting as a conduit between vessel and well, is arranged to allow safe operation of various types of tooling for well maintenance including plugging and abandonment operations. The intervention system is deployed and installed on a subsea christmas tree or already capped wellhead. In general, the system can be divided into three sub-systems or packages.

Upper riser package (URP)

Contains a series of safety barriers allowing for safe travel of Slickline and E-Line tooling. The principle objective of this section of the system is provision for fluid and gas sealing around the string when full well bore pressures and temperatures are experienced as in a live well operation. This aspect of the system also affords the ability to shear the tool string wire and disconnect at this level in the event of an emergency surface situation with the deployment vessel in a drift off, drive off or power black out scenario.

Mid Riser Package (MRP)

Lubricator riser sections of pre-determined length that accommodates the E-Line / Slick line tool string length. The connections are of bolted flange or hubbed type with a Stress Joint providing additional strength terminated by a hydraulic connector to enable quick release.

Lower Riser Package (LRP)

This package provides the ability to close the well against fluid and gas pressures, so that the upper package can be removed in the event of  a system malfunction or emergency situation. It provides pressure containment barriers and can be used on any design of subsea christmas tree. This package, which includes a fully compliant Emergency Shutdown System(ESD), has a gas sealing gate valve, a BOP with shear and seal capability and an H4 connector. This package also has ancillary entry points to allow chemical injection, flushing, choke and kill and cementing operations. Subsea well intervention systems can be deployed in a wide range of water depths (300 to 3,000 ft) from a low-cost, widely available monohull vessel. This technology (and its deployment system) can deliver significant cost savings to well intervention projects compared to current designs.

Benefits

The technology will, through the increased well intervention frequency, deliver:

•  Increased subsea well productivity in middle-to-late well life
•  Higher economic recovery per well

It should be noted that similar lubricator/intervention systems have been built and have been successfully deployed over the last 2-3 years.