基于反射波相位特征的井外界面方位判别法

Position determination of the interface out of a borehole based on the phase feature of reflected waves

单井成像是一种利用井外界面上产生的反射波进行界面探测的井下声学成像技术,但目前该技术在界面方位判定中还存在缺陷.本文从弹性波动方程出发,推导了反射波声压和位移的相位变化规律,建立了一种依据反射波相位的界面方位判别法:反射波与哪个区域中的入射波在声压和位移的相位特征上可以满足反射波相位变化规律,则反射波就来自哪个区域.文中用数值模拟获得的信号进行了界面方位识别,结果表明本文给出的方法是有效的.该方法的主要优点在于,仅依靠来自于井下的接收信号就可以将成像区间限定在井径平面的某一象限内.

Single-well imaging is an imaging technique using reflected waves to detect the interface out of a borehole underground. But there is a weakness in the existing imaging technique on the position determination of an interface. Based on the law of reflected waves＇ phase changing, a new method for the determination of an interface position is proposed in this article. Only in the region the interface exists, the rule about the phase of the reflected wave should be satisfied. And this region will be found with the phase characters of reflected waves. The principle on position judgment is proved theoretically, and the numerical simulation is given. The results indicate this method is valid and feasible. The most important advantage is that with the data received in the borehole alone the imaging zone can be defined in a certain quadrant in the radial plane of a borehole.