摘要
页岩的微观结构相对于常规储层更加复杂,目前大多数应用于估算横波速度的岩石物理模型仅适用于各向同性岩石。考虑页岩储层中黏土颗粒的定向分布和水平缝引起的各向异性,综合自相容近似(SCA)、微分等效介质模型(DEM)、Backus平均和Brown-Korringa方程,构建了一种适用于页岩的各向异性模型;然后将矿物组分、孔隙度和孔隙纵横比等代入到所建立的各向异性模型中,即可获得相应的横波速度。将广泛应用的各向同性模型(Kuster-Toks9z理论,SCA,Xu-White模型)和构建的页岩的各向异性岩石物理模型应用于实际页岩工区的岩心和测井数据的速度估算。计算结果表明,利用构建的各向异性岩石物理模型估算页岩的横波速度与实测数据吻合得很好,与各向同性有效介质模型相比具有更高的精度。
The microstructure of shale is more complex than conventional reservoir,while most of rock physics models for estimating P-wave and S-wave velocity are only suited to isotropic rocks at present. In consideration of the preferred orientations of clay particles and bedding parallel cracks,an anisotropic rock physics model was presented,combining the self-consistent approximation( SCA),the differential effective medium( DEM),the Backus average and the Brown-Korringa equation,and then S-wave velocity could be obtained by substituting the mineral content,porosity and pore aspect ratio into the constructed rock model. Three widely used isotropic models( Kuster-Toks?z theory,SCA and Xu-White model) and the constructed rock physics model are used to calculate Pwave and S-wave velocity of core samples and well data for the practical shale area. It is illustrated that is P-wave and S-wave velocity calculated by the constructed rock physics model are in good agreement with the measured data,with higher predicted accuracy than the isotropic models.
引文
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