套管井中的多极源声波测井

Multipole Source Acoustic Logging in Cased Holes

The theory of multipole source acoustic logging has been stated, and an expression of acoustic field excited by multipole source in a cased hole in the time domain is obtained on the basis of the mathematically derivating. The acoustic waveforms in both open hole and cased hole well-cemented have been computed and plotted by using the descrete wave number technique. The theoretical analysis shows that the shear wave of formation in a cased hole can be directly measured with multipole source acoustic logs and cased wave and compressional wave of formation are inhibited. The comparision between the plotted waveforms in the cased hole by this approach and those in an open hole shows completely identical. Thus in a cased hole, the same wayas in open hole can be used to evaluate the formation properties.