Internal tree cap and itc running tool

Abstract

Internal tree cap (ITC) adapted to be installed in the bore of a subsea well unit or to an internal tubular element of the same, comprising a locking element for releasably locking the internal tree cap to said subsea well unit or internal tubular element. The ITC further comprises a fluid channel extending through a fluid barrier between the lower and upper part of the internal tree cap, which fluid channel is blocked by a burst element adapted to break and open for fluid flow through the fluid channel when exposed to a predetermined pressure difference over the burst element. The invention also relates to an ITC running tool and a locking mechanism for supporting the ITC in the tool.

Description

[0001]The present invention relates to an internal tree cap and a tool for running the internal tree cap. In addition, the invention relates to methods of using the tree cap and the tool.BACKGROUND[0002]Due to the two-barrier philosophy for subsea hydrocarbon wells, an upper and a lower plug are conventionally installed in the bore of a subsea X-mas tree or its internal elements, such as the tubing hanger. It is known to replace the upper plug with an internal tree cap, the tree cap having features in addition to just blocking for fluid connection.[0003]Known internal tree caps are installed and retrieved through a marine riser from a surface installation. Thus, such installing or retrieving operations are cumbersome since they require the establishment of the riser from the surface and down to the well tree. Establishing the riser takes time and one needs to use a rig. Rigs are not always easily available and are also expensive to rent on a day-to-day basis.[0004]In addition, in so...

AI Technical Summary

Benefits of technology

The patent describes a tool for use in a subsea well that can be latched and unlatched from a support platform. The tool has a fluid connection to the wellhead and can include a bend or filter to prevent debris from blocking the fluid channel. The tool also has a mechanism to apply pressure to move a hydraulic piston, which forces a split ring into engagement with the wellhead or tubular member. The tool is cost-efficient and easy to use.

Problems solved by technology

Thus, such installing or retrieving operations are cumbersome since they require the establishment of the riser from the surface and down to the well tree.

Establishing the riser takes time and one needs to use a rig.

Rigs are not always easily available and are also expensive to rent on a day-to-day basis.

In addition, in some instances the PTV-line (plug testing valve) can be blocked, making it impossible to test the space between the lower plug and the internal tree cap.

With a conventional internal tree cap run inside a riser, one faces difficulties solving such problems accompanying such situations.

For instance, retrieval of the internal tree cap can possibly not be done due to the hydrostatic lock formed by the sealed-off space below the internal tree cap.

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