超声脉冲窄带激励的水泥环第二界面探测方法

The evaluation method about cement bonding quality of the second interface based on ultrasonic pulse narrowband excitation

如何评价水泥环的第二界面固井质量一直是声波测井领域的世界性难题。该文利用有限元方法研究了基于超声脉冲反射法的水泥环第二界面固井质量探测方法。数值模拟了不同声源脉冲宽度及不同声阻抗地层对第二界面超声反射回波的影响。研究结果表明采用窄带的激励信号源可有效提高水泥环第二界面反射波回波幅度,有望解决水泥环第二界面固井质量评价问题。制作了水泥环第二界面具有胶结缺陷的实验室样品及大型固井质量刻度井,在此基础上开展了基于窄带超声脉冲激励的实验室及刻度井群实验研究。实验结果表明满足水泥环第一界固井质量良好条件,采用窄带的超声脉冲回波技术可有效评价水泥环第二界面固井质量。

How to evaluate cement bonding quality of the second interface has been a worldwide problem in acoustic logging field.This article researches measurement method of the second interface based on ultrasonic pulse echo by using the finite element method.The influence of different bandwidth and different acoustic impedance of formation on ultrasonic echo of the second interface is simulated numerically.The signal energy of the second interface can be effectively improved with the narrowband signal,so cement bonding quality of the second interface may be solved by this method.Laboratory samples with cement sheath defects at the second interface and large cement bonding calibration wells are all fabricated.On this basis,laboratory and calibration well tests are carried out.The test results show that when first interface of cement sheath is well bonding,narrowband ultrasonic pulse echo technique can be used to evaluate cement bonding quality of the second boundary.