| 摘要 |
A multi-function apparatus designated as a "Liner Stub Assembly", run in and set in an existing cased well at the end of a work pipe string is used to add a liner-equipped branch well to an existing cased well in a way which provides full access to both wells. Pre-fabricated mobile straight tubular connectors (Liner Stubs) are installed and sealed by on-board explosive means which accurately cut a window of pre-determined shape and dimensions in the existing well casing and weld to it the Liner Stub's stop collar to make downhole a leak-proof tubular junction of the two wells, by means of such short connectors. In the first two embodiments, the Liner Stub is thrust from the housing of the Assembly and cemented into a side-pocket hole drilled through the casing window. In a third embodiment, a stationary "Pre-curved Liner Assembly" and its associated by-pass tubing are installed and sealed by similar on-board explosive means, but remain affixed inside the existing casing. This provides full access to the branch well, but only a restricted access to the cased well. Both wells are still independently operable. In all cases, the Assembly housing allows the quick recovery, through the work string, of casing remains and other debris from the well. In a fourth embodiment, the housing of said Assembly and the explosively-bonded tubular connectors of the first three embodiments, are included, as tool guides, in an Apparatus for jet-drilling of a branch borehole and for installing in said borehole a liner made from a coupling-free segment of a coiled tubing, hung and sealed in each type of bonded connector. The preferred jet-driling process makes use of a steerable nozzle at the end of a spoolable tubular ombilical, inserted in said liner segment, and made more buoyant at its lower end, so as to guide and lift the liner's bottom end off the low side of the deviated borehole. Conventional drilling tools, if required, are also inserted in the cemented and sealed Liner Stub, or in the installed Pre-curved Liner. They are guided, in part, by the Apparatus while drilling the branch borehole, for additional savings, The Apparatus and its surface-controlled, on-board, tools provide the means of reaching the objective of a sealed connection between branch liner and casing with a minimum number of trips of the work pipe string, thus reducing installation labor costs. Some parts of the Apparatus are re-usable, thus reducing the capital cost of the downhole equipment.
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