带扇形窜槽的套管井声场

Acoustic field in a cased well with a sectorial crossing channel

首次使用2.5维的有限差分算法对带窜槽的套管井声场进行了数值研究,计算得到了带有不同大小窜槽套管井的声场展开图及井轴上不同源距的接收波列。本文还应用2维谱的方法对带窜槽的套管井声场进行了分析研究。发现窜槽的存在影响了纵波头波的速度,其大小决定纵波头波的幅度。并且只有当窜槽形成角度大于30°时,才能从接收波列中被鉴别。

To study the possibility of detecting the crossing channel by using a traditional logging tool, acoustic field generated by a monopole source in a cased well with a crossing channel of various angles is simulated by 2.5-D finite difference method for the first time. Snapshots of normal stress and synthetic time-domain waveforms are displayed. The two-dimensional spectrum in wave-number and frequency domains is also calculated, where the influence of the channel is clearer than that in the waveforms. Numerical study demonstrated that a crossing channel can be detected and sized if its angle is greater than 30 degree, and larger offset and lower frequency source are favorable to detect and size the crossing channel.