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在处理实际声波测井模式波数据或用模式波的反演地层参数时,必须考虑测井仪器对频散模式波传播的影响。本文介绍了一种用具有等效弹性模量的圆柱体来模拟声波测井仪器的等效理论,并将该理论推广应用到电缆、随钻多极子声波测井。在波长大于仪器半径的前提下,将井中的多极子声场与该等效仪器模型进行声导纳/阻抗匹配,便可导出这一理论。通过数值模拟和现场资料对该理论的有效性和实用性进行了验证,验证结果证明该理论既简单又足够精确。利用该理论模型处理实际资料时,通过调整仪器等效弹性模量和半径在给定频段标定仪器的影响,而不必考虑仪器的具体材料和结构。本文以电缆偶极子声波测井现场资料的频散校正为例,进一步证明了该等效理论处理现场资料的准确性和高效性。
The effects of logging tools on dispersion-mode wave propagation must be considered when dealing with actual sonic logging mode wave data or with modeling wave inversion of formation parameters. This paper presents an equivalent theory of simulating acoustic logging tools using cylinders with equivalent elastic moduli, and extends the theory to cable, while drilling, multipole sonar logging. Under the condition that the wavelength is larger than the radius of the instrument, the acoustic admittance / impedance matching between the multipole sound field in the well and the equivalent instrument model can be derived. The validity and practicability of the theory are verified by numerical simulation and field data. The verification results show that the theory is simple and precise enough. When using this theoretical model to process actual data, it is not necessary to consider the specific material and structure of the instrument by adjusting the equivalent elastic modulus and radius of the instrument to calibrate the instrument in a given frequency band. In this paper, the dispersion correction of on-site data of cable dipole sonic logging is taken as an example to further prove the accuracy and efficiency of this equivalent theory in the field data processing.