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    松辽盆地古龙页岩油粘弹各向异性波场模拟及其响应特征研究

    Investigation of viscoelastic anisotropy in wavefield simulations and their response characteristics for Gulong shale oil within the Songliao basin

    • 摘要: 松辽盆地北部青山口组古龙页岩油资源潜力大,勘探开发前景广阔。然而,古龙页岩储层受页理密度、裂缝、地层压力等因素控制,具有强各向异性和强衰减的“两强”特征,导致古龙页岩地震响应机制复杂并且响应特征尚不明确。针对古龙页岩层系地层粘弹各向异性特征,采用“测井信息−地震层位−构造特征−岩心实验”多信息融合实现初始模型细化分层,进而构建古龙页岩米级尺度的高精度复杂粘弹各向异性模型。基于粘弹VTI介质模型的本构关系建立波动方程,利用交错网格有限差分算法,对古龙页岩层系进行地震波场数值模拟。研究表明:无论是爆炸源还是横波震源,粘弹各向异性对古龙页岩地震振幅都产生了较大的影响。古龙地区的“两强”特性下的地震响应结果表明,在古龙地区考虑Q补偿的各向异性成像技术对于高精度地震成像至关重要。

       

      Abstract: The shale oil resources of the Qingshankou Formation in the northern Songliao Basin exhibit substantial potential, highlighting extensive opportunities for exploration and development. However, the Gulong area is controlled by factors such as bedding density, fractures, and formation pressure, showing pronounced characteristics of strong anisotropy and attenuation in geophysical properties. Such factors lead to a complex seismic response mechanism in Gulong shale, leaving the response characteristics somewhat ambiguous. To tackle the viscoelastic anisotropy characteristics of the Gulong shale formation, a multi-faceted fusion approach integrating well logging data, seismic stratigraphy, structural features, and core experiments was utilized. This method refined the initial model through meticulous stratification, enabling the development of a high-precision and sophisticated viscoelastic anisotropy model on a meter scale for the Gulong shale area. The wave equation grounded on the constitutive relationships of a viscoelastic vertically transverse isotropy (VTI) medium model was developed. The staggered-grid finite difference algorithm was employed for the numerical simulation of the seismic wavefield in the Gulong shale formation. Findings reveal that under explosive source or shear-wave source conditions, the seismic amplitude of the Gulong shale is markedly influenced by the viscoelastic anisotropy. The seismic response outcomes under the strong anisotropy and attenuation characteristics in the Gulong area underscore the importance of incorporating Q-compensated anisotropic imaging technology for achieving high-precision seismic imaging in the region.

       

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