Theoretical And Experimental Study Of Azimuthal LWD Acoustic Logging Transducer

The LWD Azimuthal Acoustic Logging is critical in the measurement of azimuthal imaging in the wellbore.Aiming at the major issue of azimuthal velocity measurement in formations,this paper comprehensively considers the piezoelectric-wellbore modulation,studies the theoretical and experimental aspects based on the azimuth transducer.According to the performance requirements of the azimuthal transducer,this paper analyzes the effects of structure and material parameters on performance and designs a sound source that meets the requirements of logging while drilling,determines the comprehensive application of the azimuthal instrument in the uneven or cross-interface formations.The text is divided into the following two parts:The first part designs a azimuthal transducer based on the special requirements of the azimuthal acoustic logging while drilling.Firstly,in order to make the sound insulator better press the drilling wave and the resonant frequency of the transducer falls within the effective sound insulation resistance band of the sound insulator,studied the relationship between resonant frequency and size,and material parameters.Then,in order to improve the azimuth resolution of the azimuthal logging in formation,studied the variation of the beam angle of the azimuthal sound source directivity curve with the open angle of the transducer.In order to overcome the defects of the large noise environment in the logging while drilling,studied the relationship between radiant energy and excitation frequency and compared energy to monopoles.Based on the above analysis,determines that the structural parameters of the piezoelectric ceramic in the transducer:transducer are open angle ?=60°,height h=90 mm,thickness T=6 mm,the material is PZT-4 material,and the structural parameters of the package casing are open angle ?=64°,height h=122mm,thickness T=10mm,the material is epoxy resin material.The second part studies its application effect in the azimuth logging while drilling,which is based on the above-mentioned azimuthal transducers.Firstly,analyzes the sound source parameters such as the resonant frequency,directivity,and radiant energy of the above transducer.Then,experimentally studies the sound insulation effect of the azimuthal sound source,and numerically studies the ability of the azimuthal acoustic wave instrument to evaluate the formation information in uniform formation,anisotropic formation and cross-interface formation,and conducts experimental verification in the experimental well.