基于非结构化网格的复杂构造建模方法研究———以四川双鱼石地区为例
Study on modeling method of complex structure in Sichuan Shuangyushi Area based on unstructured grid
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摘要: 基于非结构化网格,利用petrel软件建立地质模型,提出弱化相交网格剖分方法优化地质构造模型,对复杂构造区的高陡构造展开建模方法研究,探讨了复杂构造条件下利用地球物理数据分析地层特征的方法并有效应用于四川双鱼石地区。结果表明:四川盆地双鱼石地区有一系列呈北东南西向展布、近平行的褶皱断高构造群,利用非结构化网格对高陡构造地质建模有较好的效果,直观有效解释了双鱼石地区断裂构造空间展布特征,对解决复杂褶皱变形、断裂发育地区构造拟合效果较好。利用非结构网格法下的属性插值,建立三角剖分的复杂断层模型,恢复了双鱼石地区主要目标岩层茅口组与栖霞组的地层特征,对断裂切割地层的方式与组合特征有效恢复,区域上结合渗透率和孔隙度模型,得到双鱼石地区渗透率与孔隙度平面分布特征。孔隙度与渗透率模型计算结果表明,双鱼石地区总体渗透率介于0.11%~7.49%,平均渗透率为2.09%;孔隙度介于0.010~1.052,平均孔隙度为0.26。总体上双鱼石地区茅口组与栖霞组渗透率与孔隙度较小,属于致密岩层,不同区域上岩层孔隙度与渗透率有一定程度的变化,西南部渗透率略微高于东北部区域。非结构化网格的运用对解决复杂构造区地质特征的有效表征提供了新的研究思路。Abstract: Based on unstructured grids,petrel software was used to build a geological model to propose a weakened intersection grid division method to optimize the geological structure model,and developed modeling methods for high and steep structures in complex structural areas,and explored the method of using geophysical data to analyze stratigraphic characteristics under complex structural conditions and effectively applied to the Sichuan Shuangyushi Area. The results show that the Shuangyushi Area of the Sichuan Basin has a series of nearly parallel fold-height structure groups spreading north,southeast,and west. The use of unstructured grids has a good effect on modeling high and steep structures,which intuitively and effectively explained the spatial distribution characteristics of faulted structures in the Shuangyushi Area,and it has a good effect on solving complex fold deformation and structural fitting in areas with developed faults. Using the attribute interpolation under the unstructured grid method,the complex fault model of triangulation was established,and the stratigraphic characteristics of the Maokou and Qixia Formations,the main target rock formations in the Shuangyushi Area were restored,and the method and combination characteristics of the fracture cutting strata were effectively restored. Regionally,the permeability and porosity models were combined to obtain the characteristics of the plane distribution of permeability and porosity in the Bishishi Area. The calculation results of the porosity and permeability models show that the overall permeability of the Shuangyushi Area is between 0.11% and 7.49%,and the average permeability is 2.09%; the porosity is between 0.01 and 1.052,and the average porosity is 0.26. Generally speaking,the permeability and porosity of Maokou Formation and Qixia Formation in Shuangyushi Area are relatively small and belong to tight rock formations. The porosity and permeability of rock formations in different regions vary to a certain extent. The permeability in the southwest is slightly higher than that in the northeast. The application of unstructured grids provides new research ideas for solving the effective characterization of geological features in complex structural areas,and has certain theoretical and practical significance.