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US 4,265,110 AGranted
Downhole cable tension measuring apparatus
AssigneeSchlumberger Technology Corporation
InventorPierre A. Moulin
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AssigneeSchlumberger Technology Corporation
InventorPierre A. Moulin
Estimating the term…
Downhole cable tension measuring apparatus according to the invention is connected between a cable and well-logging apparatus suspended from the cable in a borehole. A rod is placed between the cable and the well-logging apparatus so as to elongate elastically under the effect of cable tension. A sleeve, fixed at one end of the rod, surrounds the rod. A transformer, the primary of which is wound on the rod, the secondary of which is wound on the sleeve, detects the relative longitudinal displacement of the other end of the rod with respect to the sleeve. Two primary windings displaced on the rod are alternately excited to generate two signals in the secondary coil in order to correct temperature drifts of the circuits. The rod and sleeve are made of the same metal so that each of them will elongate similarly as a function of temperature. The apparatus is placed in a pressure-balanced oil-filled chamber.
Apparatus for measuring the downhole tension applied to a cable suspending a well-logging apparatus in a borehole, comprising:
Apparatus for measuring the downhole tension applied to a cable suspending a well-logging apparatus in a borehole, comprising:
Apparatus according to one of the claims of 7 or 8 further comprising means for combining said first and second induced signals to generate an output signal calibrated in sensitive-element-elongation units.
Dependencies are inferred from the claim text.