分扇区水泥胶结测井胶结质量的定量评价研究*

为了实现分扇区水泥胶结测井仪(SBT)对第二界面(水泥-地层界面)的检测,本文在SBT的声系结构基础上,通过优化声源入射角提出检测水泥胶结质量的新方法。本文首先分析了不同充液条件下薄壁管激发的模态波频散特征;之后应用三维有限差分算法模拟薄壁管和实际套管井在斜入射声源激励下的声场,由计算结果提出激励速度"平台"上的模态有利于检测界面胶结质量;最后通过一系列波场模拟与分析来论证应用接收信号定量评价一二界面胶结质量的可行性。结果表明,特定的入射角可激励出对应速度"平台"处的模态,该模态波的特征较好的体现在接收信号中,可利用其幅度衰减程度判断水泥的胶结质量。该成果为套管井二界面水泥胶结质量的定量检测提供了研究基础。

Research on quantitative evaluation of cementing quality using the segmented bond logging technique

Based on the Segment Bond Tool (SBT) structure, a new method using obliquely incident ultrasonic wave is explored to improve the quantitative evaluation of cementing quality on the second interface. Firstly, the dispersion relations of pipes under different conditions are analyzed. Then, finite difference algorithm is applied to simulate the acoustic fields of the pipe and physical model which both motivated by obliquely incidence wave, the simulation results suggest the modes on the 'plateau' help evaluation. The acoustic fields of the cased wells with different cementing qualities are simulated and the received waves are used to demonstrate the feasibility of cementing evaluation. Results show the modes on the 'plateau' can be motivated by obliquely incidence wave and the modes' amplitude attenuation can be used to evaluate the cementing quality. This method provide the basis for quantitative evaluation of cementing quality on the second interface.