CPC E21B 47/08 (2013.01) | 20 Claims |
1. An apparatus for measuring the profile of a wellbore, the apparatus comprising:
a cylindrical body having first and second ends threaded for connection in line with a drill string and having a passage extending through the cylindrical body between the first end and the second end thereof;
a plurality of arms pivotally coupled to the cylindrical body, each of the arms biased to pivot so as to move a free end thereof radially away from an outer surface of the cylindrical body, the plurality of arms being angularly spaced apart around the cylindrical body and arranged in a plurality of tiers, each of the tiers comprising three or more of the arms, the tiers being spaced apart axially from one another along the cylindrical body, and each said arm of a first said tier being angularly offset relative to the arms of a second said tier;
sensors operable to directly or indirectly measure radial extension of each of the arms from the cylindrical body; and
a holding mechanism operable to hold the arms in a retracted configuration and to selectively release the arms to pivot away from the cylindrical body, wherein the holding mechanism comprises one or more of i) a hydraulic actuator, ii) an electric actuator, iii) a magnetic system, and iv) a pneumatic actuator.
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