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    基于横波各向异性地震反演的陆相页岩油游离烃含量预测

    Prediction of free hydrocarbon content in continental shale oil based on shear-wave anisotropic seismic inversion

    • 摘要: 准确评价页岩油的可动性对陆相页岩油的高效勘探和开发至关重要。游离烃含量(S1)作为热解参数中表征游离态烃的关键指标,是评价陆相页岩油可动性的重要依据。然而,游离烃含量的定量地震预测较为困难,传统方法需要通过总有机碳含量间接估算。实测资料表明,松辽盆地古龙凹陷青山口组页岩具有非常显著的地震各向异性,且等效各向异性参数\sigma 与游离烃含量存在良好的相关性。针对这一问题,提出了一种基于地震横波叠前各向异性反演的页岩油储层游离烃含量预测方法。该方法通过直接反演垂直横波阻抗、各向异性剪切模量和垂直横波速度,计算得到各向异性参数\sigma ,并结合岩石物理关系实现游离烃含量的定量估算。将该方法应用于在古龙凹陷陆相页岩油工区,预测结果与实钻资料及地质认识高度吻合,能够为陆相页岩油可动性甜点区的地震预测提供重要的方法支持。

       

      Abstract: Accurately evaluating the movability of shale oil is essential for efficient exploration and development of continental shale oil reservoirs. The free hydrocarbon content (S1), a key pyrolysis parameter, is a crucial indicator for evaluating the movability of continental shale oil. However, quantitative seismic prediction of S1 poses challenges and typically relies on indirect estimation through total organic carbon (TOC) content. Well log data show that the Qingshankou Formation shales in the Gulong Sag of the Songliao Basin exhibit pronounced seismic anisotropy, and the effective anisotropy parameter \sigma exhibits a strong correlation with S1. To address these challenges, a seismic prediction method for free hydrocarbon content in shale oil reservoirs is proposed, based on pre-stack anisotropic inversion of shear waves. This method derives the anisotropy parameter \sigma by directly inverting vertical shear impedance, anisotropic shear modulus, and vertical shear velocity, and then quantitatively estimates S1 using established rock physics relationships. Applied to continental shale oil reservoirs in the Gulong Sag, the method yields predictions that closely match drilling data and geological interpretations, providing a robust basis for seismic identification of shale oil movability sweet spots.

       

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