US 4,559,709 AGranted

Apparatus for measuring the internal dimensions of a tube, notably in a well, and displacement measurement method applicable to such an apparatus

AssigneeSchlumberger Technology Corporation

InventorsJean H. Beseme, Jose R. Corral, Bernard J. Glotin

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Abstract

A caliper logging sonde is equipped with a plurality of fingers (54) mounted swivelably with respect to its body member (51). The movement of each finger (54) is transmitted to a respective bar (176) in magnetic material. This bar moves within a longitudinal tube (136) which is mounted in a sealed manner with respect to the sonde body member so that its interior is subjected to the pressure outside the sonde and so that the space around this tube is not subjected to this pressure. Around the tube is mounted a transducer winding (150) whose self-inductance depends on the degree of penetration of the bar (176) and hence on the displacement to be measured. A measurement of this self-inductance is obtained by the study of the variation of a current going through the coil when a voltage transient is applied to the coil terminals.

Claims13

Dependent claims

Apparatus for measuring the internal dimensions of a tube, notably in a well, comprising:

an elongated sonde body member movable within the tube to be measured;
a plurality of sensing fingers mounted on the sonde body member for contacting the walls of the tube and movable with respect to the sonde body member in response to variations in the internal transverse dimensions of the tube when the sonde body member is moved within the tube;
a barrell structure linked with the sonde body member to provide an interior space sealed against exposure to the pressure prevailing in the tube;
and
a displacement transducer associated with each sensing finger, comprising:
a blind tube protruding in a sealed manner into the interior space of the barrel structure so that at least part of the outer surface at the closed end of the blind tube is sealed within the interior space, while the inside of the blind tube is exposed at the open end to the pressure prevailing in the tube to be measured;
a mobile element extending into the inside of the blind tube through its open end;
detection means located within the interior space in a position around the at least part of the outer surface of the blind tube, the detection means being sensitive to variations in the position of the mobile element within the blind tube to produce an electrical signal corresponding to the movement of the mobile element;
and
transmission means mechanically linking the mobile element and the resepective sensing finger to cause movement of the mobile element within the blind tube in response to movement of the finger.

7 more elements

Apparatus for measuring the transverse dimensions of a tube, notably in a well, comprising:

sonde body member movable within the tube to be measured;
a plurality of sensing fingers movably mounted on the sonde body member;
means for resiliently loading each finger in a radial direction away from the sonde body member so as to bias the fingers into contact with the internal wall of the tube and to cause the fingers to move in accordance with changes in the internal transverse dimensions of the tube as the sonde body member is moved longitudinally within the tube;
a plurality of displacement transducers, each comprising a magnetically permeable core and a coil which are mounted on the sonde body member for relative movement with respect to each other;
transmission means for transmitting the transverse movement of each finger to a respective one of the displacement transducers;
and, further comprising for each coil, a resistor connected in series with the coil;
means for applying a predetermined current to the core through the resistor;
means for producing, after build up of current in the coil, the discharge of the coil through said resistor;
and detection means capable of detecting the time required for the current of decreasing amplitude in the coil to go through a value corresponding to a predetermined fraction of its initial amplitude in the coil.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/452,232Filed 22 Dec 1982
Priority: FR 81 2417923 Dec 1981
Granted: 24 Dec 1985
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G01B 7/13
For measuring diameters: internal diameters
E21B 47/08
Survey of boreholes or wells: measuring diameters or related dimensions at the borehole
E21B 47/12
Survey of boreholes or wells: means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the…
G01B 7/287
For measuring contours or curvatures: using a plurality of fixed, simultaneously operating transducers