| 摘要 |
<p>A method and apparatus for enlarging an inverted arcuate underground path between two surface locations (O,E) is disclosed, where the cuttings from the enlarging are removed. After the drilling of a pilot borehole (B), and possibly after some reaming operations, a reamer (8) and hole cleaner (20) are pulled through the path, with the reamer (8) rotating as the drill string (9) in the path rotates. The rotation of the drill string (9) also powers a positive displacement pump (14) inside of the hole cleaner (20), which pumps fluid and entrained cuttings to the surface behind the hole cleaner (20). Fluid may also be pumped into the reamer (8) from behind the hole cleaner (20), preferably by way of an inlet pipe (12) which surrounds the outlet (11) from the pump. The hole cleaner includes an agitator (6), also powered by the rotation of the drill string (9), which agitates the fluid and cuttings while the drill string (9) is rotated but is not being pulled to the surface. Pressure control may be maintained either by monitoring the fluid in and out of the path together with the volume of the cuttings, or by direct monitoring of the pressure at the reamer (8). <IMAGE></p> |
