有效测量套管井泄漏Lamb波衰减的实验研究

Experimental study on effective measurement of leakage Lamb wave attenuation in cased hole

低密度水泥在油气井中的广泛应用使得常规的声阻抗类测井方法难以准确、有效地评价固井质量,而声波倾斜入射在套管中激发的弯曲型Lamb波对水泥的性质及胶结情况具有很高的分辨能力,能够很好地解决低密度水泥的固井质量评价问题。弯曲型Lamb波对套管后介质声学信息的响应反映在声波衰减中,因此该文通过实验研究了激发弯曲型Lamb波的有效方式,分析了声波入射和接收角度对Lamb波衰减的影响。实验结果表明,入射和接收角度在一定范围内变化时,虽然激发出的Lamb波模式均为弯曲型Lamb波,但在同一套管模型下测量的声波衰减值会有差异,选择激发弯曲型Lamb波的最有效方式,计算得到的Lamb波衰减对套管后介质的灵敏度才会最高。

The wide application of low density cement in oil and gas wells makes it difficult for conventional acoustic impedance logging methods to accurately and effectively evaluate the cementing quality.However,the flexural Lamb wave stimulated by the slant incident acoustic wave in the casing has a very high resolution on the properties and cementation of cement,which can well solve the problem of cementing quality evaluation of low density cement.The response of the flexural Lamb wave to the acoustic information of the medium behind the casing is reflected in the attenuation.Therefore,this paper studies the effective way to excite the flexural Lamb wave through experiments,and analyzes the influence of the incidence and reception angle of the acoustic wave on the attenuation of the Lamb wave.The experimental results show that when the incident angle and the receiving angle change within a certain range,although the mode waves excited are all flexural Lamb waves,the attenuation values measured in the same casing model will be different.The most effective way to excite flexural Lamb waves is selected,and the sensitivity of the Lamb wave attenuation to the medium behind the casing will be the highest.