heave compensated riser & vessel floor for rigless well intervention

The Stability of Rig while Running a Riser for Coiled Tubing, Wireline and Other Equipment for a Vessel of Opportunity

Enhanced Riser Management by Running Tools Through the Cylinder’s Center Wright’s Well Control Services (WWCS) is developing a self-contained stabilization system “that heaves itself” via two cylinders working in unison against surge and waves. The WWCS Heave Comp System breaks with convention by offering a central longitudinal conduit extending through the center of its cylinders. Where other rig-based kits externally stabilize a riser, the WWCS device is machined from its midpoint with a 6in ID pathway to allow tools to run through the center of the mechanism. This new assembly offers a higher degree of riser management from a vessel and is comparable to that of rig, allowing for continued abandonments, workovers, completions and production operations. Stability from a Nitrogen-Filled Cylinder Assembly The system’s two cylinders are aligned internally, share a common central head or base plate, and are housed in the same exoskeleton. These nitrogen-filled cylinders are in fluid communication working in tandem to exert force against each other. While the lower cylinder absorbs the force of the surge subsea on the riser, the upper cylinder compensates for the wave motion experienced by the deployed vessel. The opposite ends of these cylinders – the top of the upper cylinder and bottom of the lower cylinder – travel through a central cavity and move up and down against a common base plate. The WWCS Heave Comp System is Designed to Minimize Motion The heave comp is designed for 150,000 lbs of tension load and has 20’ feet of total stroke. Once the bowls and slips are installed on to a false rotary floor, the tension is set, the system is rigged, and the riser is attached to a BOP; additional coiled tubing or wireline can run through a moonpool or off the stern of a vessel via a secondary cantilever. In this configuration the coiled tubing is only moving 3” to 4” inches via the heave compensated floor, allowing the WWCS system to offer all the benefits of both a riser and a rig, and enhance a vessel’s utilization for P&As and other subsea interventions. The system has a 10K pressure rating and can work in up to 10,000’ WD depending on riser weight.

Heave Compensation for the Rig Floor

This new WWCS stabilization design can also be applied directly to the vessel itself. Nitrogen-filled cylinders, similar to those used for the riser, are applied to a heave compensated floor attached to a vessel deck. When the riser and vessel floor heave comp systems are coupled, an increased level of stability is provided for rigless operations.

Engineered for Safety

The WWCS system is engineered with a 4:1 safety ratio where the tolerances for the riser and floor are adjustable to a predetermined pressure by manipulating the amount of nitrogen in the cylinders. Depending on multiple factors: expected load, motion, type of ship, the weight of the riser, water depth, season and changing weather conditions, the cylinders are pressured for optimal performance. The cylinders extend or retract to provide the desired length for the field conditions encountered. The heave comp riser can also serve as a redundant system for a rig providing an additional layer of safety.

Nitrogen enhances the safety of the heave comp system as it is environmentally friendly, is less likely to leak, and through a series of relief valves can provide a fluid response to force within milliseconds. Forty to eighty gallon bottles of nitrogen can be pre-charged and do not need to be placed directly next to the cylinders for effective pressurization. Safety is further reinforced with hybrid emergency quick disconnects (HEQD) which allow for the system to eject the riser from the BOP for contingent or unplanned operations.

For offshore oil well control services and pumping services, complex well intervention operations or related engineering services, call the business office of WWCS at 281-446-0273 or send an email.

Technology Breakthroughs &
One-of-a-Kind Equipment

Wright’s Well Control Services (WWCS) engineers and executes numerous first-to-market services for clients. Ask the expert team at Wright’s about customized solutions for the most challenging offshore environments in the Gulf of Mexico (GOM) and beyond.

	The First Rigless Wireline Intervention in the GOM
	State-of-the-Art Class I, Div 2 Explosion-Proof Electric Line Units
	Largest Mechanical Cutter on the Gulf Coast
	First Subsea Acid Job Off of a Dive Boat
	Ultra-Deepwater Hydrate Skid & Pump Solution
	One-of-a-Kind Gas Separator