Apparatus and method for determining the position of a tool in a borehole
A method is described for determining the path length between a borehole entrance opening and a probe that is suspended to move through the borehole by an elastic cable, the method comprising: generating a cable feed rate signal representative of the current rate at which the cable is moving past the entrance opening of the borehole; generating a cable feed rate correction signal representative of current changes in the length of the cable; combining the cable feed rate signal and the cable feed rate correction signal to provide a compensated cable feed rate signal; generating a probe velocity signal representing the current rate at which the probe is moving along the borehole; detecting whether the magnitude of the difference between the probe velocity signal and the compensated feed rate signal exceeds a predetermined value; selecting the compensated feed rate signal when the magnitude of the difference between the probe velocity signal and the compensated cable feed rate does not exceed the predetermined value; and selecting the probe velocity signal when the magnitude of the difference between the probe velocity signal and the compensated feed rate signal exceeds the predetermined value.
- Assignee:
- Sundstrand Data Control, Inc., Redmond, WA
- Patent Number(s):
- US 4797822
- OSTI ID:
- 6059941
- Resource Relation:
- Patent File Date: Filed date 31 Dec 1986
- Country of Publication:
- United States
- Language:
- English
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