METHOD OF ELECTROMAGNETIC TESTING IN MULTICOLUMN WELLS Russian patent published in 2009 - IPC E21B47/08 G01N27/90 

FIELD: oil and gas industry.

SUBSTANCE: usage: well surveys. It is provided for defectoscopy of metal pipes, located in wells, particularly steel drilling, casing and tubing pipes, with simultaneous calculation of walls thickness of each of pipes. In method of electromagnetic testing in multicolumn wells, consisting in measuring of electromotive difference, brought on in receiver coil by whirling currents, excited in steel casing or tubing pipes by means of electromagnetic field decay process, activated by interrogation pulse of excitation current in exciter coil, for activation of exciter coil it is used alternation of excitation current impulses of different duration in the range from 10 millisecond up to 200 millisecond after each 200 millisecond, and measurement of pipe parametres of small diametre is implemented after switching off of drive pulse of excitation current of less duration, for instance in the range from 10 up to 40 millisecond, and measurement of pipe parametres of high diametre is implemented after turning off of drive pulse of excitation current with more duration, for instance in the range from 40 millisecond up to 200 millisecond.

EFFECT: range of application expansion and improving of defectoscopy.

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