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Publication Date: 2005-Mar-02

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The Prior Art Database


The objective is to develop a reeled completion system initially for use offshore in high costs areas, with further refinement the system may be used onshore as well.

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The objective is to develop a reeled completion system initially for use offshore in high costs areas, with further refinement the system may be used onshore as well. The "Donut" completion system is based on the principle of launching individual completion components through a lubricator. The coiled tubing string passes through the centre of several of the completion components allowing them to be stacked in the lubricator. When the appropriate length of coiled tubing has been run each component is launched into the well. The system makes provision for running all essential components including the packer, safety valve and tubing hanger. The system is designed for deepwater subsea use, to eliminate the need for large diameter risers to allow the passage of the completion equipment. The large drilling rig required to run and tension the large risers can be eliminated and the completion equipment can be run and retrieved from a suitable monohull vessel. However the system may eventually be adapted for surface applications. Coiled tubing completions are well suited where smaller subsea fields have a limited life in the 3-10 years instead of 10-20 years. Typical monobore completions can be divided into the following parts: the lower completion, the packer assembly to isolate the annulus, the safety valve, and the tubing hanger. It is proposed that separate trips run each part of the coiled tubing completion into the well. The lower completion may be restricted to tail pipe and TCP guns. Other completion components may be included depending on the required complexity of the completion. It is envisaged that these additional components will be capable of being adapted for running with this system. The innovation is based on having the required completion components secured and stacked one on top of another inside a subsea lubricator ready for running. The completion components are so designed to allow the coiled production tubing to pass through their centres. The lubricator with its stacked completion is deployed to the subsea tree on the end of a flexible coiled tubing riser where the coiled completion tubing is preinstalled inside. Once the lubricator is landed and latched onto the subsea tree, the completion components will be launched when the correct length of coiled tubing has been run into the well. While running one lubricator and its components, the next lubricator can be loaded and tested on surface. The new system is designed so that a monohull vessel equipped to run spoolable riser and production coiled tubing can be adapted to run and retrieve coiled tubing completions. The deepwater drilling rig will be used to drill log and run the production liner. A horizontal tree is then run landed and latched on the wellhead. The tree would be prepared to allow the installation to the spoolable tubing hanger. The rig can be released once the horizontal tree has been pressure tested. The well...