超声脉冲回波测井信号影响因素数值模拟

Numerical Simulation of Influencing Factors on Ultrasonic Pulsed Echo Logging Signals

针对套管井超声脉冲回声测井进行固井质量评价和套管检测问题,建立了6层介质模型进行数值模拟考察并分析了超声脉冲回波测井中的各种影响因素。对完全胶结情况下数值模拟的全波进行套管地层环形空间介质声阻抗和套管壁厚反演,验证了数值模拟方法及反演方法的正确性。在此基础上数值模拟分析了水泥环厚度变化,套管水泥界面(Ⅰ界面)和水泥地层界面(Ⅱ界面)存在流体环等因素对接收回波的影响。数值模拟了完全胶结情况下地层参数变化对超声脉冲回波测井接收信号的影响,接收回波后半段幅度随着地层声速及阻抗的增加而增加。数值模拟分析结果有助于对超声脉冲回波测井资料解释结果进行正确分析。

In order to get more accurate evaluation on cementing quality and casing condition using ultrasonic pulsed echo logging data,a model including 6 layers was established for numerical simulation and analysis of influencing factors on ultrasonic pulsed echo logging data.Inversion to the acoustic impedance of annulus medium and cased formation and the wall thickness of casing was carried out using the full wave data numerically simulated under the condition of full cementation.Then the thickness of cement ring,the fluid rings on casing cement interface(interface I)and formation cement interface(interface II)were numerically simulated to analyze how they influence echoes.In addition,the influences of formation parameters on echoes is simulated numerically.The amplitude of the second half of the received echo increases with the increase of acoustic velocity and impedance.The results of numerical simulation provide useful information to correct analysis of the interpretation results of ultrasonic pulse echo logging data.