System and method for monitoring drill bit depth
US4976143A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 4, 1989 |
| Grant date | Dec 11, 1990 |
| Priority date | — |
| Expiry date | Oct 4, 2009 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B45/00
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Methods and apparatus for accurately determining drill bit depth are provided. A hook load is sampled at a rate of at least 4 Hz and is compared to a low threshold to establish a slips-in condition. A determination is made retroactively that the drill string stopped moving when the hook load passed through a high dynamic threshold. On the slips-out procedure, the identical high threshold is used, with movement established when the hook load exceeds the high threshold. The high dynamic threshold corresponds to the points at which the drill string actually stops and starts moving in the slips-in and slips-out procedures. The apparatus provided is a drawworks encoder mounting assembly which retrofits an auxiliary brake section of the drawworks or the rotary seal air coupler of a drawworks clutch. A split ring gear fits around and is secured to the rotating cylinder of the rotary seal air coupler. The split ring gear is part of a pulley having another gear and a drive belt, such that rotation of the drum and rotorseal air coupler cylinder is translated to a shaft of an encoder coupled to the second gear. The encoder thereby tracks the rotational movement of the drawworks drum. At desir…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.