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US 8,037,765 B2Granted
Electromagnetic acoustic transducer using magnetic shielding
AssigneeBaker Hughes Incorporated
InventorArcady Reiderman
Life of this patent
Estimating the term…
Abstract
A combined electromagnetic acoustic transducer (EMAT) is disclosed that uses magnetic shielding to increase the efficiency (defined as the received signal per unit of excitation current). In addition, electromagnetic shielding may also be used to reduce the direct coupling between the transmit and receive coils.
Claims19
An apparatus configured to evaluate a tubular, the apparatus comprising:
- an electromagnetic coupling device comprising a coil, a magnet;
- and
- a non-conductive shield comprising a soft magnetic material, configured to be conveyed into the tubular and coupling acoustic energy within the tubular;
- wherein the non-conductive shield is configured to shield the magnet from a radio frequency (RF) field of the coil and boost a magnetic field at a surface of the tubular.
1 more element
A method of evaluating a tubular, the method comprising:
- conveying an electromagnetic (EMAT) coupling device comprising a coil, a magnet and a non-conductive shield comprising a soft magnetic material into the tubular;
- conveying an electrical current to the coil;
- using the non-conductive shield to shield the magnet from a radio frequency (RF) field of the coil and boost a magnetic field at a surface of the tubular, and
- coupling acoustic energy into the tubular.
1 more element
A non-transitory computer-readable medium product having stored thereon instructions that when read by a processor cause the processor to perform a method, the method comprising:
- using an electromagnetic coupling device including a coil, a magnet and a non-conductive shield including a soft magnetic material in a tubular and producing a wave in the tubular having a polarization that is at least one of:
- (i) a compressional wave, (ii)-a shear wave, (iii) a transversely polarized shear wave, (iv) a Lamb wave, or (v) a Rayleigh wave
- wherein the non-conductive shield is configured to shield the magnet from a radio frequency (RF) field of the coil and boost a magnetic field at a surface of the tubular.
Dependencies are inferred from the claim text.