Apparatus for determining depth of a well tool in a borehole by measurement of tension
Abstract
Abstract IN ACCORDANCE WITH AN ILLUSTRATIVE EMBODIMENT OF THE PRESENT INVENTION, APPARATUS FOR ACCURATELY AND CONTINUOUSLY DETERMINING CHANGES IN DEPTH OF A TOOL IN A BOREHOLE ARE DISCLOSED. MORE PARTICULARLY, THE TENSILE FORCE BETWEEN THE TOOL AND ITS SUPPORTING CABLE IS MEASURED, AS IS THE MOVEMENT OF THE CABLE AT THE SURFACE OF THE EARTH. THE TENSION AND CABLE MOVEMENT MEASUREMENTS ARE THEN COMBINED IN A COMPUTER ALONG WITH A PLURALITY OF CONSTANTS REPRESENTATIVE OF VARIOUS CHARACTERISTICS OF THE CABLE AND ITS SURROUNDING MEDIUM TO PRODUCE AN OUTPUT SIGNAL REPRESENTATIVE OF THE MOVEMENT OF THE TOOL DUE TO THE CHANGE IN TENSION. THE COMPUTER SOLVES A SECOND ORDER DIFFERENTIAL EQUATION WHICH INCLUDES INVERSE AND INVERSE SQUARED FUNCTIONS OF THE TOOL DEPTH. POTENTIOMETES WHICH VARY DIRECTLY LINEAR WITH DEPTH ARE PROVIDED IN APPROPRIATE FEEDBACK PATHS OF THE COMPUTER TO PRODUCE THESE INVERSE AND INVERSE SQUARED FUNCTIONS, THE COMPUTER OUTPUT SIGNAL IS THEN COMBINED WITH THE ORIGNAL CABLE MOVEMENT MEASUREMENT TO PRODUCE A SIGNAL REPRESENTATIVE OF THE INSTANTANEOUS CHANGES IN DEPTH OF THE TOOL.
Inventors
- 👤 William A Whitfill
Bibliographic Details
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-01-04 | 1974-07-06 | 1975-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |