| 摘要 |
The present invention generally provides an apparatus and method for forming a pilot hole in a formation. In one aspect of the present invention, the apparatus may comprise a starter mill connected to a bearing mill by a body joint. The apparatus may further comprise a lead bearing connected to a starter mill by a lead joint. Preferably, an outer diameter of the bearing mill is about the same as an inner diameter of a wellbore. As the lead bearing travels along the concave, the apparatus will bend between the bearing mill and the lead bearing. The bend urges the starter mill into contact with the wellbore wall. In another aspect of the present invention, a method for forming a pilot hole in a wellbore includes running a tool into the wellbore, the tool comprising a starter mill disposed between a first bearing and a second bearing. While running the tool along a concave of a whipstock, the tool bends between the first and second bearing and urges the starter mill to form the pilot hole.
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