| 摘要 |
A method of milling a window 35 through a casing 30 in a primary well bore 20 and drilling an enlarged sidetracked well bore 25 comprises running a drilling assembly 100 into the primary well bore 20. The drilling assembly 100 has at least one cutting apparatus (Fig.3, 330,340) adapted to drill an enlarged borehole. A window 35 is milled through the casing 30, the enlarged sidetracked well bore 25 is then drilled. The milling and drilling steps are performed in one trip into the primary well bore (20). |
