Acoustic field in cased well excited by the linear phased-array transmitter

The useful mode wave can be stimulated effectively by using of the linear phased-array transmitter with controllable beam steering characteristic. The synthetic acoustic waveforms excited by the linear phased-array transmitter in cased boreholes are calculated with various cement bonding cases for the two interfaces outside the steel casing. When the generation conditions of the refracted compressional wave and the refracted shear wave are reached successively by regulating the direction of acoustic beam radiated from the linear phased-array transmitter, the refracted compressional wave and the refracted shear wave are strengthened respectively with both good bonding interfaces. The refracted compressional wave and the refracted shear wave can be stimulated obviously and the casing wave can be suppressed effectively, even when the casing and cement(or the cement and formation) is not bonded. Contrastively the formation information can not be detected in the received full waveform excited by one point source.