Depth control methods and apparatus for boreholes
Abstract
Abstract IN ACCORDANCE WITH AN ILLUSTRATIVE EMBODIMENT OF THE INVENTION, METHODS AND APPARATUS FOR ACCURATELY DETERMINING THE TRUE DEPTH OF A TOOL SUPPORTED IN A BOREHOLE BY AN ELASTIC CABLE ARE DESCRIBED. TO ACCOMPLISH THIS, A SHEAVE WHEEL AT THE SURFACE OF THE EARTH MEASURES CABLE MOVEMENT AND GENERATES PULSES REPRESENTATIVE OF INCREMENTAL CABLE MOVEMENT. THE TENSION ON THE CABLE AT THE SURFACE OF THE EARTH IS MEASURED AND USED IN COMBINATION WITH CERTAIN CALIBRATIOIN CORRECTIONS TO GENERATE CORRECTION PULSES WHICH ARE EITHER ADDED TO OR SUBTRACTED FROM THE INCREMENTAL CABLE MOVEMENT PULSES TO PRODUCE CORRECTED CABLE MOVEMENT PULSES. THESE CORRECTED PULSES CAN THEN BE USED TO DRIVE A SUITABLE RECORDING DEVICE AS A FUNCTION OF TRUE CABLE MOVEMENT OR TO CAUSE REFERENCE MARKS TO BE PLACED ON THE CABLE SO THAT THE CABLE CAN BE LATTER USED FOR DEPTH CONTROL PURPOSES APART FROM THE PULSE CORRECTION COMPUTING SYSTEM.
Inventors
- 👤 F David Hurlston
Bibliographic Details
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |