| 摘要 |
An underreamer with pressurized water activated lateral cutters pivotally mounted thereon and being spring biased to urge them in longitudinal alignment with the underreamer. A removable constrictor socket is cooperatively mounted adjacent to the distal end of the piston rod so that a user can select one of several designs depending on the magnitude of drill fluid pressure to be applied on the bottom of the well. The lower end of the underreamer is provided with several contiguous cutting teeth arranged in a circle with a relatively small separation inbetween so that it may continue to work even if the well collapses. The cutting teeth enhance the turbulence of the drill fluid. The underreamer is lubricated with drilling fluid applied up to a predetermined pressure without opening the lateral cutters. After a given predetermined amount of pressure, the lateral cutters open perpendicularly. |
