| 摘要 |
The present invention concerns an apparatus for modifying sidewalls of a borehole. The apparatus includes a longitudinal housing adapted to fit inside the borehole. The housing includes a first end portion, a second end portion, and a side portion between said end portions, adapted to face the sidewalls of the borehole. Means are provides on the side of the housing for removing material from said borehole sidewall. The housing is adapted to be rotated with a controlled rotational speed in relation to said borehole sidewalls and to be fed in a controlled rate of longitudinal motion in relation to said borehole. Furthermore, the invention relates to a method for making a borehole with internal, helical grooves. |
