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改进的Backus平均模型已被证明能较好地模拟Bakken页岩,对于同样的对象,本文采用各向异性DEM模型进行分析,分别模拟了干酪根作为岩石背景基质与内部包含物时岩石的等效弹性张量随干酪根含量的变化规律,发现将干酪根看作岩石基质时模拟结果更接近目标页岩的实验室测量数据,与目标岩样的电镜扫描结果一致;继而将粘土矿物的纵横比以及干酪根与粘土矿物的弹性模量看作自由参数,通过最小二乘法求取了各向异性DEM模型的最佳输入参数,由此得到的预测结果优于改进的Backus平均模型,说明采用各向异性DEM模型来分析有机质的含量和分布对岩石弹性性质的影响是有效可行的.最后,拟合生成了目标页岩的实际刚度系数与含氢指数的关系曲线,得出岩石刚度与干酪根成熟度之间具有正相关性.
The improved Backus average model has been shown to simulate the Bakken shale well. For the same object, this paper uses an anisotropic DEM model to analyze the kerogen model as the equivalent of rock background matrix and internal inclusion rock The elastic tensor changes with the kerogen content. It is found that when the kerogen is regarded as a rock matrix, the simulation result is closer to the laboratory measurement data of the target shale, which is consistent with the electron microscope scanning result of the target rock sample. The clay mineral aspect ratio And the elastic modulus of kerogen and clay minerals are regarded as free parameters. The optimal input parameters of anisotropic DEM model are calculated by the least squares method, and the prediction results obtained are better than the improved Backus average model, It is feasible and feasible to analyze the effect of the content and distribution of organic matter on the elastic properties of rocks by using the anisotropic DEM model.Finally, the relationship between the actual stiffness coefficient of the target shale and the hydrogen index is obtained by fitting, and the relationship between rock stiffness and kerogen There is a positive correlation between maturity.