Sammendrag
This article presents a set of acoustic measurements conducted on the Statoil funded
Behind Casing Logging Set-Up, designed by SINTEF Petroleum Research to resemble
an oil well casing. A set of simple simulations using COMSOL Multiphysics were
also conducted and the results compared with the measurements. The experiments
consists of measuring the pressure wave radiated of a set of Lamb waves propagating
in a 3 mm thick steel plate, using the so called pitch-catch method. The Lamb
waves were excited by a broadband piezoelectric immersion transducer with center
frequency of 1 MHz. Through measurements and analysis the group velocity of the
fastest mode in the plate was found to be 3138.5 m/s. Measuring the wave radiated
into the water in a grid consisting of 8x33 measuring points, the spreading of the plate
wave normal to the direction of propagation was investigated. Comparing the point
where the amplitude had decreased 50 % relative to the amplitude measured at the
axis pointing straight forward from the transducer shows that the wave spread out 3.2
mm after propagating 140 mm in the plate.
Behind Casing Logging Set-Up, designed by SINTEF Petroleum Research to resemble
an oil well casing. A set of simple simulations using COMSOL Multiphysics were
also conducted and the results compared with the measurements. The experiments
consists of measuring the pressure wave radiated of a set of Lamb waves propagating
in a 3 mm thick steel plate, using the so called pitch-catch method. The Lamb
waves were excited by a broadband piezoelectric immersion transducer with center
frequency of 1 MHz. Through measurements and analysis the group velocity of the
fastest mode in the plate was found to be 3138.5 m/s. Measuring the wave radiated
into the water in a grid consisting of 8x33 measuring points, the spreading of the plate
wave normal to the direction of propagation was investigated. Comparing the point
where the amplitude had decreased 50 % relative to the amplitude measured at the
axis pointing straight forward from the transducer shows that the wave spread out 3.2
mm after propagating 140 mm in the plate.