套管井中相控线阵声源激发声场的实验室物理模拟研究

为了探讨任意胶结状况下的套管井中均能直接并清晰的测量到地层信息的可行性,开展了套管井缩小模型的声波测井实验室物理模拟研究。实验测量了套管井不同胶结状况下相控线阵声源做发射器时的全波波形。通过对相控线阵声源不同偏转角时测量的全波波形分析表明,在Ⅰ、Ⅱ界面均胶结良好时随着相控线阵阵元间激励延迟时间的增加,当相控线阵声源的声束偏转角先后等于地层第一临界角和第二临界角时可使井孔中接收的地层滑行纵波和滑行横波幅度分别加强到最大;在套管井Ⅰ界面胶结差以及自由套管中,仍有效的探测到了地层的滑行纵波和横波信息。此实验结果验证了在任意胶结状况下的套管井中均能直接测量到地层信息的可行性,为开发新一代的套管井相控线阵声波测井仪奠定了实验基础。 

Experimental studies of linear phased-array transmitter acoustic logging in cased wells with scaled borehole models

Laboratory cased-hole acoustic logging simulations are developed with the linear phased-array transmitters in scaled cased well models for evaluating the feasibility of extracting formation acoustic parameters through casing. The full waveforms are measured with different cement bonding models.By analyzing the measured wavetrains and the time-slowness correlation graphs,it is showed that when the generation conditions of the refracted compressional wave and the refracted shear wave are reached successively by regulating the direction of acoustic beam radiated from the linear phased-array transmitter,the refracted compressional wave and the refracted shear wave are strengthened respectively with both good bonding interfaces.The refracted compressional wave and the refracted shear wave can be stimulated obviously and the casing wave can be suppressed effectively,even when the casing and cement(or the cement and formation) is not bonded.Based on these observations,it is worthwhile apply the linear phased-array transmitter to determine formation velocities,particularly in poorly bonded cased well.The works establish the experimental foundation for new generation cased-hole acoustic logging tool development.