双声源激发随钻测井声电耦合波理论模拟

发布时间：2018-07-27 21:20

【摘要】：随钻单极源声波测井中,由于钻铤模式波的干扰而使地层纵波速度的测量变得困难.孔隙地层的声电转换物理效应给我们提供了通过测量转换电信号实现声学参数测量的可能性.针对随钻声电测井,采用Pride声电耦合方程组描述井外孔隙地层的声电耦合波场,考虑随钻环境条件下的边界条件,采用实轴积分法计算出了随钻声电测井瞬态响应的波场.计算结果表明,声电转换比与电缆声电测井量级相同,也说明随钻环境下声电效应是可应用的.但是,从得到的电场波形图中可以观察到,钻铤模式波成分虽有压制,但仍然存在.为了削弱钻铤模式波,鉴于钻铤的声波速度已知,我们尝试利用双发射源测井方法,通过控制源间距及合适的发射延迟时间对钻铤模式波进行进一步压制.结果表明,采用双源后的井内转换声场和电场波形中,钻铤模式波被有效地抑制,残余钻铤波的相对振幅明显减小,压制效果在电场波形中尤为明显,地层波的信噪比显著增强,有利于地层纵波速度的提取.
[Abstract]:In monopole source acoustic logging, it is difficult to measure the velocity of formation longitudinal wave due to the interference of collar mode wave. The physical effect of acoustoelectric conversion in porous formation provides us with the possibility to measure acoustic parameters by measuring and converting electrical signals. According to the acoustoelectric logging while drilling, the acoustoelectric coupling equations of Pride are used to describe the acousto-electric coupling wave field in the pore formation outside the well. Considering the boundary conditions under the condition of the environment while drilling, the wave field of the transient response of the acoustoelectric logging while drilling is calculated by using the solid axis integral method. The calculated results show that the acoustoelectric conversion ratio is the same as that of cable acoustoelectric logging, and that the acoustoelectric effect in drilling environment is applicable. However, it can be observed from the obtained electric field waveform that the wave composition of drill collar mode is suppressed, but still exists. In order to weaken the drill collar mode wave, in view of the known acoustic velocity of the drill collar, we try to further suppress the drill collar mode wave by controlling the source spacing and the appropriate emission delay time. The results show that the drill collar mode wave is effectively suppressed and the relative amplitude of residual drill collar wave is obviously reduced, especially in the electric field waveform. The signal-to-noise ratio (SNR) of formation wave is significantly enhanced, which is beneficial to the extraction of formation P-wave velocity.
【作者单位】：吉林大学物理学院声学与微波物理系;
【基金】：国家自然科学基金(40974067,11134011,41474098)资助
【分类号】：P631.81

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