一种周期性管柱中声波频谱评价方法

An evaluation method for acoustic spectrum in periodic pipelines

基于声波频谱特性对钻杆等周期性管柱中信息传输的重要性,提出了基于改进雷达图法的声波频谱多级评价方法.该方法针对频谱中通阻带交替分布的特性,选取通带上限频率、通带下限频率、通带宽度、通带内峰值、通带内峰值对应频率和通带能量作为评价通带特性的三级指标,将通带评价函数值作为评价频谱特性的二级指标.基于雷达图法构造了多指标的评价向量与评价函数,通过对评价函数值的计算量化表征通带与频谱特性.研究了轴向拉应力对管柱中声波频谱特性的影响,并建立了判别标准.结果表明:拉应力的存在对声波频谱及频谱中通带特性影响显著,随拉应力增加,频谱特性评价指标先增后减,存在频谱特性最优的峰值点.该结果能够用来指导载波频率的优选和声波中继器位置的设计,从而降低井下因素对钻柱中信号的不利影响.

Based on the importance of acoustic spectrum characteristics for information transmission in drill string and other periodic pipelines,a multi-level evaluation method of acoustic spectrum based on improved radar chart was proposed.According to the characteristics of alternating distribution of passband and stopband in spectrum,the upper limit frequency,lower limit frequency,bandwidth,peak value,peak-corresponding frequency and energy of the passband were selected as third-level indexes to evaluate passband characteristics,and the values of the passband evalution function were used as second-level indexes to evaluate spectrum characteristics.A multi-index evaluation vector and function were constructed based on radar chart method and the passband and spectrum are quantitatively characterized by the evaluation function.The influence of axial tension stress on the spectrum characteristics of acoustic wave in pipelines was analyzed and the criteria for judging the spectrum characteristics were established.The test results show that the existence of tensile stress has a significant impact on the acoustic spectrum and passband characteristics.With the increase of tensile stress,the evaluation index of spectrum characteristic increases first and then decreases,and there exists a peak point with the best spectrum characteristic.The results can be used to help select carrier frequency and relay installation position in practical application to reduce the adverse effects of downhole factors on acoustic signals in drill string.