Catenary Intervention

Floating vessel intervention system

Catanery CT service.

A more efficient CT intervention technique

Interventions on small platforms with limited deck space and loading capacity often require the use of jackup barges, lift boats, or workover rigs. The high cost and limited availability of these offshore vessels has delayed or prevented many required interventions, leaving a number of wells nonproductive or producing below their optimal capacity.

The catenary CT intervention technique uses smaller floating vessels and proprietary safety and well-control systems that eliminate the need to lift the CT reel and the pumping equipment to the platform. The resulting lower total intervention cost combined with an ability to work on extremely small platforms enable interventions that increase profitability and extend production life.

Catanery CT system.
ReelCONNECT multiple CT string connection system assembly skid.

The floating vessel approach

Schlumberger has years of experience using small floating vessels to perform offshore CT interventions. These vessels, which include anchored barges, dynamically positioned vessels, and standard supply boats, enable CT intervention on almost any offshore installation.

Full-scale CT operations have been performed from supply boats with deck space as small as 16 m × 9 m, and drafts under 5 m. The floating CT system is an ideal solution for performing well intervention work, particularly for wells located on small-front platforms or platforms that prohibit placing CT and pumping equipment onboard. And with at least four vessel anchoring points in place, operations can be performed with wave heights up to 5 m.

The catenary system reduces total intervention time by approximately 25%, with less time needed for transferring equipment to platform, rigging up, and pressure testing. Additionally, a shorter advance notice period is required for job preparation and mobilization.