偏心情况下方位声波固井质量评价测井数值模拟研究

在水平井或大斜度井段，套管和测井仪器由于重力作用通常存在向下偏心的现象，这会对方位声波固井质量评价仪（AABT）的测量响应造成干扰，使其不能有效判别水泥窜槽方位。本文利用三维有限差分算法分别模拟了仪器偏心和套管偏心情况下方位声波固井质量评价仪的测量响应，分析了偏心距离与各方位接收波形幅度之间的关系，并在此基础上提出了一种水泥窜槽方位测量校正方法。数值模拟结果表明，仪器偏心对AABT测量响应影响很大，难以从首波幅度分布曲线中直接获取水泥窜槽的方位。基于仪器偏心时在自由套管条件下的响应特征，可以实现对仪器偏心效应的校正。从校正后的首波幅度分布曲线中，可以准确地获得水泥窜槽的方位。套管偏心对AABT测量响应影响很小，通常可以忽略。本文的工作为之后AABT实际资料的处理奠定了理论基础。

Numerical Simulation of Azimuthally Acoustic Cementing Quality Evaluation Logging Under Eccentric Conditions

In horizontal or high-inclination well sections, the casing and logging tool usually have downward eccentricity due to gravity, which interferes with the measurement response of azimuthally acoustic bond tool (AABT). The azimuth of the cement channeling cannot be effectively distinguished by AABT under these circumstances. In this paper, the measurement responses of AABT under the conditions of tool eccentricity and casing eccentricity are numerically simulated by a three-dimensional finite difference algorithm. The relationship between the eccentricity distance and the amplitude of received waveform in each azimuth is analyzed, and an azimuth measurement correction method of the cement channeling is proposed. The numerical simulation results show that the tool eccentricity has a great influence on the measurement response of AABT, and it is difficult to directly obtain the azimuth of the cement channeling from the amplitude distribution curve of the first arrival. Based on the response characteristics of the eccentric tool in the free casing condition, the eccentricity effect of the tool can be corrected. The azimuth of the cement channeling can be accurately obtained from the corrected amplitude distribution curve of the first arrival. The influence of casing eccentricity on the measurement response of AABT is quite small and can usually be ignored. The work of this study lays a theoretical foundation for the processing of AABT actual data.