Apparatus for drilling lateral drainholes from a wellbore
US6220372A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 4, 1997 |
| Grant date | Apr 24, 2001 |
| Priority date | — |
| Expiry date | Dec 4, 2017 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B17/20
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Apparatus for drilling lateral drainholes from a well casing comprises a flexible shaft having a bit at the lower end; the shaft extending through a shaft guide conduit anchored within the casing adjacent an oil-bearing formation. The "L" shaped guide conduit re-directs the shaft from an path parallel to the casing, through an elbow, to a path substantially perpendicular to the casing. The flexible shaft is formed of a helically wound outer coil spring and one or more helically wound and smaller inner coil springs residing concentrically therein. Each coil spring is closely fitted within the other. Each coil spring is wound opposite in direction to that of the next adjacent coil spring so as to interfere when under torsion. Bushings are located within the elbow for causing the shaft to flex and turn while permitting rotation and axial movement therethrough. A motor imparts torque into the top of the shaft, preferably through an intermediate driveshaft. The shaft is movable up and down within the casing. Accordingly, when the motor is rotating the bit, and the shaft is lowered, the shaft guide conduit supports the shaft, guides it through the elbow and directs the bit against the ca…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.