| 摘要 |
A borehole may be drilled utilizing the bottom hole assembly! 0, 50 with a downhole motor 14, 110, which may offset at a selected bend angle. A bend for directional drilling may be provided by a PDM1 or by a RSD. A gauge section 36 secured to the pilot bit 18 has a uniform diameter bearing surface along an axial length of at least 60% of the pilot bit diameter The bit or reamer 16 has a bit face defining the cutting diameter of the drilled hole. The axial spacing between the bend and the bit face is controlled to less than fifteen times the bit diameter The downhole motor, pilot bit and bit may be retrieved from the well while leaving the casing string in the well. |
