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What is a slick joint in the completion string?

asked Jun 4, 2016 in Engineering by antonjoh (2,870 points)

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answered Jun 4, 2016 by antonjoh (2,870 points)
The primary purpose of the slick joint is to enable an annulus seal to be established by the closure of the Blow-Out Preventer (BOP) pipe rams/Variable Bore Rams around the external profile of the slick joint.  The slick joint also allows control fluid to be conveyed to and from the functions of the tool(s) below via the ports, which have been gun-drilled longitudinally through the wall of the slick joint.

The secondary purpose of the slick joint is to space out the shear joint and packoff sub to the correct elevations within the BOP stack to allow BOP closure.

The slick joint is interfaced with the Tubing Hanger Running Tool (THRT) or Tree Cap Running Tool (TCRT) at its lower end and the Subsea Test Tree (SSTT) at its upper end.  The length of the joint should be such that the SSTT emergency disconnect latch interface is below the BOP blind rams, and the shear joint above the SSTT is across shear rams.  The slick joint itself should be positioned across pipe/ Variable Bore Rams (VBR) rams.
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answered Jun 4, 2016 by antonjoh (2,870 points)

Externally, the slick joint will have a surface finish no greater than 125 rms in the area of the ram seal surface.

Internally, the slick joint should have a bore suitable to enable the passage of wireline or coiled tubing equipment, especially the drift diameter of the tree cap plug.  All internal bore transitions are to be tapered so as not to interfere with or snag the wireline tools and equipment.

The wall of the slick joint should accommodate the conduits necessary for the conveyance of control fluid required to effect discrete functions of tool(s) below the slick joint.

The wall thickness of the slick joint should be adequate to withstand the combinations of internal and external loading possible (combined pressure, tension, and bending) under all conditions expected during handling, including both normal and contingency operations.

The material from which the slick joint is made should be suitable for the duty required, and for the fluids with which it may come into contact.  It may not be necessary to accommodate H2S and acid stimulation jobs, due to the limited exposure time to produced and injected fluids.

The slick joint should be designed to be suitable for the subsea BOP and ram arrangement details specific to the installation vessel.

Note: A study of the stack-up tolerance should be studied of the BOP, horizontal tree, tubing hanger, tree cap, and SSTT systems.  The study should ensure that the space-out of the slick joint, shear joint, and packoff sub will permit closure of the BOPs with which they interface in both the tubing hanger and tree cap modes.  It is preferred that this be accomplished without changing components from one mode to the other.  However, if this is not possible, it is recommended to provide sufficient alternative components to provide proper space-out for both modes via changing-out one or more components.

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