基于波场重构反演(WRI)的时移地震反演方法以二氧化碳地质封存动态监测模型数据为例

    A time-lapse seismic inversion method based on wavefield reconstruction inversion for the dynamic monitoring model data of geologic CO2 sequestration

    • 摘要: 二氧化碳地质封存监测中,时移地震资料能够反映二氧化碳注入引起的饱和度以及相关储层物性参数的微小变化,对评估封存安全性与有效性具有重要意义。传统全波形反演虽能利用全波形信息,但其非线性较强,且对初始模型和低频成分较为依赖,易产生“跳周”现象。为解决上述问题,本文将波场重构反演方法引入时移地震反演,并结合并行反演和双差反演策略,形成适用于二氧化碳地质封存监测的反演流程。模型测试结果表明,基于并行策略的波场重构反演方法能够有效抑制假象并恢复速度变化区域的几何形态,双差反演策略进一步增强了反演的稳定性。其中基于双差策略的波场重构反演方法在强弱异常区均能准确反映速度扰动,假象显著减少,边界清晰度与幅值恢复效果优于传统方法。该方法不仅提高了目标区域的反演精度,而且增强了储层变化的可识别性,为二氧化碳地质封存的四维地震监测提供了一种稳健、可靠的技术手段。

       

      Abstract: In the monitoring of geologic CO2 sequestration, time-lapse seismic data can capture the CO2 injection-induced subtle changes in CO2 saturation and associated reservoir physical properties, which are crucial for evaluating the storage safety and effectiveness. Although conventional full-waveform inversion can exploit full-waveform information in time-lapse seismic data, it is highly nonlinear and strongly dependent on the initial model and low-frequency components, rendering it prone to cycle skipping. Hence, this study incorporated wavefield reconstruction inversion (WRI) into time-lapse seismic inversion, combined with parallel and double-difference inversion strategies, to establish an inversion process for monitoring geologic CO2 sequestration. Model test results show that the WRI, based on the parallel inversion strategy, effectively suppressed artifacts while also recovering the geometric morphologies of velocity-change zones. The double-difference inversion strategy further enhanced inversion stability. The WRI, based on the double-difference strategy, accurately captured velocity perturbations in both strong and weak velocity-change zones, yielding significantly reduced artifacts and outperforming conventional methods in both boundary clarity and amplitude recovery. Overall, this inversion method improves the inversion accuracy of the target area while also enhancing the identifiability of reservoir changes, serving as a robust and reliable technical approach for 4D seismic monitoring of geologic CO2 sequestration.

       

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