Experimental studies of linear phased-array transmitter acoustic logging in cased wells with scaled borehole models

Laboratory cased-hole acoustic logging simulations are developed with the linear phased-array transmitters in scaled cased well models for evaluating the feasibility of extracting formation acoustic parameters through casing. The full waveforms are measured with different cement bonding models.By analyzing the measured wavetrains and the time-slowness correlation graphs,it is showed that 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.Based on these observations,it is worthwhile apply the linear phased-array transmitter to determine formation velocities,particularly in poorly bonded cased well.The works establish the experimental foundation for new generation cased-hole acoustic logging tool development.