声波测井中泥饼折射滑行波分析方法初探

Preliminary analysis on refracted slide wave of mudcake in sonic logging

渗透层段因泥浆过滤形成泥饼,造成井径缩径,这对声波时差测井会产生一定影响。本文设计了一种三层介质的声波传播模型,首次提出了泥饼滑行波和泥饼折射滑行波的概念,给出了存在泥饼时的声波时差计算公式。用数值分析法研究了声波滑行波传播时间随泥饼厚度的变化规律,表明发射探头到接收探头的距离控制了接收声波的来源,1m源距的常规声波测井仪器接收的总是泥饼折射滑行波,当泥饼厚度均匀且各向同性时无需进行泥饼校正。而当为提高声波分辨率减小源距时,声波测井仪器所接受到的声波受泥饼厚度的影响。

The mudcake has been formed in the permeable interval because of mud filtering,resulted in borehole diameter shrink,which has influence on delta time.The paper designed sonic propagation model of three-stratum medium,presented the conception of slide wave of mudcake and refracted slide wave of mudcake in first time and gave the computational formula of delta time when existing mudcake.It is showed by using numeric analytic method to study the rule of traveling time of sonic slide wave changing with thickness of mudeake that the distance from probe of transmitter to probe of receiver controls the source of receiving sonic wave,the common sonic logging apparatus with 1m source distance always receives the refracted slide wave of mudcake and the correction of mudcake is not needed when the thickness of mudcake is uniform and isotropic.The thickness of mudcake has influence on sonic wave received by sonic logging apparatus when reducing source distance to improve the resolution of sonic wave.