BOREHOLE MAGNET-PULSE FLAW AND THICKNESS DETECTOR Russian patent published in 2008 - IPC G01B7/02 E21B47/12 

FIELD: physics, survey.

SUBSTANCE: invention refers to geophysics and can be used for flaw detection of metal pipes, e.g. downhole, in particular, of steel drill, casing and pump-compressor pipes, as well as for simultaneous calculation of pipe wall thickness within multistring well programmes. Flaw and thickness detector contains generator system equipped with generator, timer and exciter coils; gage system with sensing coils and amplifiers, controller and transmitter of telemetry communication line (TCL). In addition, flaw detector is provided with coils identical to sensing coils spaced apart so as to eliminate generator system effect. Output of additional coils is connected to measuring system and controller providing timing measurements by depth of basic and additional measuring system. Technical result consists in increasing accuracy of column wall thickness measurement and flaw detection by registration of metal magnetic inhomogeneity and "magnetic noise" caused by permanent magnetisation due to elimination of effect of permanent magnetisation and pipe magnetic inhomogeneity on measuring signal.

EFFECT: increased accuracy of column wall thickness measurement and flaw detection.

6 dwg