不同胶结情况下套管井中声场激发谱的研究

采用实轴积分法计算套管刻度井中的声场激发谱,分析了第一、第二界面的胶结情况以及模拟地层的厚度等对井内声场的影响。数值结果显示:在套管刻度井中,模拟地层厚度的增大或第一、第二界面的胶结状况变差,该地层的外边界对井中激发谱的影响变小,在低频(小于3kHz)情况下,当外边界半径大于0.2m时,不管第一、第二界面胶结状况如何,该边界面对井中激发谱的影响基本可以忽略;在设计套管刻度井时,为减小模拟地层的外边界对井内声场的影响,既要考虑不同胶结情况下模拟地层的厚度问题,还应考虑声源测量频率的影响问题。

Study of the Excited Acoustic Spectroscopy in Cased Hole under Different Bonded Conditions

The excited acoustic spectroscopy (EAS) in cased calibration hole is calculated with the real-axis integral method. The effect on acoustic field in the hole from varied bonded-conditions at the first and second interface and the thickness of the modeling formation is analyzed. The numerical results show that the effect of the outmost boundary of the formation on the EAS in the hole decreases with the increase of the formation thickness or with the deterioration of the two bonded interfaces. At low frequencies (less than 3 kHz), the outmost formation-boundary have little effect on the EAS, when the radius of this boundary is great than 0.2 m, while effect from the two bonded interfaces can be ignored. In order to decrease the effect on the acoustic field from the artificial formation boundary in the calibration hole, not only the thickness of the modeling formation under different bonded conditions but also the measuring frequency of the source should be considered carefully when the authors design a cased calibration hole.