Casing resonant radial flexural modes in cement bond evaluation

A method of evaluating a bond on a downhole tubular comprising:

• emitting a signal into the tubular configured to induce a radial resonant frequency response;
• measuring the radial resonant frequency response induced within the downhole tubular;
• obtaining at least one of a bonded and an unbonded radial resonant frequency response of a reference tubular having approximately the same resonant frequency response of the downhole tubular;
• comparing the measured frequency response of the downhole tubular to the at least one of a bonded and unbonded radial resonant frequency response of the reference tubular;
• and
• determining the downhole tubular is bonded if its measured radial resonant frequency response is approximately the same as the bonded radial resonant frequency response of the reference tubular or determining the downhole tubular is not bonded if its measured radial resonant frequency response is approximately the same as the unbonded radial resonant frequency response of the reference tubular.