不同速度混合的阵列信号速度分析*

为了考察正交偶极子测井中同向分量的速度变化规律,该文采用不同速度传播的两个相同频率的正弦波以不同幅度比进行混合来模拟同向阵列在不同方位接收到的波形,并用波形匹配方法提取混合后的波列速度。数值结果表明,同向分量的视速度一般介于两个混合的正弦波的速度之间,且与由拟合得到的双曲正切函数比较吻合。但在特殊条件下,也会出现阵列复合波形的速度会在正弦波速度范围之外,表现出一定的异常。异常出现的条件和大小与源距、频率以及速度差有关,并可用一个简单的数学关系式表达。该文的结果还可以为实际处理不同源距的混合波测速问题提供参考。

The velocity analysis of mixed array waveforms with different velocities

In order to investigate the velocity change regulation of the in-line array waves, this paper presents a simplified waveform model, which consists of two sinusoidal waves with the same frequency and different velocities. The numerical results indicate that the obtained velocity of in-line data is generally between the velocities of those two sinusoidal waves and can be approximately fitted by using a hyperbolic tangent function. However, an abnormal phenomenon, that the obtained velocity is beyond the range of the velocities of two sinusoidal waves, will occur in special conditions. The extent and the occurrence conditions of abnormity depend on the source-receiver spacing, source frequency and velocity difference, and it can be expressed by a simple mathematical formula. Also, the conclusion of this paper can provide a reference to extract the velocity waveforms with different source-receiver distances.