| 摘要 |
The time required for establishing a multilateral well is reduced by enlarging a section of a wellbore and running a multilateral tool (7) which includes a preassembled combination of casing sections that form dual casing strings extending from the primary casing. The multilateral tool (7) incorporates a carrier section (2), a lateral section (8), and a main section (5). The tool is run with the lateral section (8) releasably held in coaxial alignment within the carrier section (2), and with the main section (5) fixed to the lower end of the carrier section (2). Once in place, the lateral section (8) is released and diverted out of a preformed window (4) in the lower end of the carrier section (2) and runs generally parallel to the main casing section (5). A lateral junction is thus formed at the carrier section window (4) in which dual casing strings are connected to the primary casing. A second window, preformed in the upper end of lateral section (8) is aligned with the bore of the primary casing when the lateral casing section is fully extended out of the carrier section window (4), thus permitting recovery of a diverting device incorporated in the carrier casing section (2) through the second window. The dual strings are then individually drilled and completed with pressure integrity between the dual strings maintained by using straddle equipment across the lateral junction.
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