DEVICE FOR MEASURING CHANGES OF INNER DIAMETER OF CASING STRINGS Russian patent published in 1998 - IPC

FIELD: oil and gas production industry. SUBSTANCE: this is used for checking technical conditions of casing strings in drill-holes. Device has ground surface equipment, communication cable and down-hole instrument with head-piece for connection of communication cable, measuring levers with units for their opening and pressing against string being investigated. Mounted on body of down-hole instrument at its different cross-sections without possibility of turning are identical rings with similar wire stops uniformly distributed over outer surface of rings tangentially to them and contacting with inner surface of casing string in opposite directions due to turning one of rings through 180 deg. EFFECT: high efficiency. 4 dwg