论文部分内容阅读
超声波水泥胶结质量评价测井是目前较为广泛使用的固井质量评价方法。将传统的脉冲回波技术与超声波斜入射方法相结合,可以形成评价固井质量的新技术。本文使用有限差分方法模拟研究了超声波斜入射时所激发出的波形特征与水泥性质以及胶结状况之间的关系。通过对三种常用水泥的数值模拟,得到了AO模式和SO模式Lamb波在不同胶结水泥及胶结情况下的声衰减系数;通过对不同厚度胶结水泥的数值模拟,得到了次生AO模式Lamb波和AO模式Lamb波的到时差与水泥性质及厚度的关系,并理论推导了水泥层厚度与时间差之间的关系,且从有限差分时域波形中提取的时间差与由理论公式计算结果能够较好的吻合。因此利用AO模式Lamb波到时及衰减信息可以在一定程度上评价水泥胶结状况及水泥厚度。
Ultrasonic cement cementation quality evaluation logging is the more widely used cementing quality evaluation method. The traditional pulse echo technology and ultrasonic oblique incidence method combined to form a new technology to evaluate the quality of cementing. In this paper, the finite difference method is used to simulate the relationship between the waveform characteristics and the nature of cement and the cementation condition induced by oblique incident of ultrasonic wave. Through the numerical simulation of three common cements, the acoustic attenuation coefficients of AO mode and SO mode Lamb wave under different cement cements and cements are obtained. Through the numerical simulation of cemented cement with different thicknesses, the secondary AO mode Lamb wave And AO mode Lamb wave to cement property and thickness, and the relationship between cement thickness and time difference was deduced theoretically, and the time difference extracted from the finite difference time domain waveform and the calculated result from the theoretical formula can be better Match. Therefore, the AO mode Lamb wave arrival and attenuation information can be used to evaluate cement bonding status and cement thickness to a certain extent.