Li Shengjie, Wang Daxing, Zhang Mengbo
State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), CNPC Key Laboratory of Geophysical Exploration, Beijing, 102249, China.
Exploration and Development Research Institute of PetroChina Changqing Oil Field Company, Xi'an, 710018, China.
Sci Rep. 2019 Sep 10;9(1):13056. doi: 10.1038/s41598-019-49559-2.
Elastic constants derived from seismic-scale measurements are often used to infer subsurface petrophysical properties based on rock-physics relationships established from either theoretic model or core-scale measurements. However, the spatial heterogeneity of rock physical properties at the local scale has a significant impact on this relation. To understand this problem, we built a scaled physical model comprised of artificial porous layers with different pore fluids. After conducting a two-dimensional marine seismic survey over the physical model, the physical modeling data ware then used to retrieve the elastic constants of the layered package. The seismic-scale results reveal that the identification of reservoir fluid properties is improved using elastic constants that is more sensitive to pore fluid properties. The results of numerical simulations show that Lamé moduli provide more insight into rock properties and pore-fluid contents than P-wave impedances, and that the relationship between the upscaled elastic constants and the effective fluid bulk moduli at the seismic scale is usually not perfectly preserved at the reservoir scale. To interpret seismic-scale elastic constants for petrophysical properties, the rock physics relationship need to be carefully calibrated. The findings will help us understand the upscaling of rock-physics transform, which will improve the accuracy of geological property predictions from seismic-scale elastic constants.
从地震尺度测量中得出的弹性常数，常被用于根据理论模型或岩心尺度测量所建立的岩石物理关系来推断地下岩石物理性质。然而，局部尺度上岩石物理性质的空间非均质性对这种关系有显著影响。为了解决这个问题，我们构建了一个由含有不同孔隙流体的人工多孔层组成的比例物理模型。在对该物理模型进行二维海洋地震调查后，利用物理建模数据反演分层组合体的弹性常数。地震尺度的结果表明，使用对孔隙流体性质更敏感的弹性常数可提高储层流体性质的识别能力。数值模拟结果表明，拉梅模量比纵波阻抗能更深入地洞察岩石性质和孔隙流体含量，并且在地震尺度上，向上尺度化的弹性常数与有效流体体积模量之间的关系在储层尺度上通常不能完美保持。为了解释用于岩石物理性质的地震尺度弹性常数，需要仔细校准岩石物理关系。这些发现将有助于我们理解岩石物理变换的尺度提升问题，这将提高基于地震尺度弹性常数的地质性质预测的准确性。
