多尺度数字岩石建模进展与展望

Progress and Prospect of Multiscale Digital Rock Modeling

数字岩石技术可对岩心进行精细数字化表征,结合数值模拟方法研究微观岩石物理属性。非常规储层岩石在不同尺度上表现出不同的特征,多尺度成像技术能以亚纳米—毫米级分辨率观测不同尺度的岩石微观组构,然而单一分辨率扫描方法无法解析跨尺度结构信息,构建多尺度、多分辨率、多组分的数字岩石模型是解决这一矛盾的关键方法。通过系统的调研,将现有的多尺度数字岩石建模方法分为两大类,分别为基于混合叠加、模板匹配和深度学习的图像融合建模方法,以及带有显式微孔网络、仅添加额外喉道和含裂缝系统的孔隙网络整合建模方法。其中:图像融合建模法能够真实反映不同尺度岩心的孔隙、矿物三维分布并进行多物理场模拟,但受计算效率限制难以实现尺度差异较大的混合建模;孔隙网络整合法能够实现多个连续尺度的建模,模型储存空间小且数值模拟效率高,但可研究的物理属性受限。此外,数字岩石工作流程还存在如何精确提取矿物、如何确定适当的代表性体积元大小等共性问题。笔者认为下一步探索方向为:利用实验数据优化建模,按需研究物理属性建模及结合均化等效理论建模,以早日形成具体的应用体系,支撑实际测井解释及油气藏开发。

Digital rock technology enables the precise digital characterization of core samples and facilitates the study of microscale rock physical properties through numerical simulations.Unconventional reservoir rocks display distinct features across various scales,and multiscale imaging technology can capture the rock’s microstructure at resolutions ranging from sub-nanometer to millimeter levels.However,single-resolution scanning methods fail to resolve cross-scale structural information,making the development of multiscale,multiresolution,and multicomponent digital rock models crucial to overcoming this limitation.Existing multiscale digital rock modeling methods can be broadly categorized into two main approaches:image fusion modeling,which relies on mixed overlays,template matching and deep learning,and pore network integration modeling,which incorporates explicit micropore networks,additional throat networks,and fracture systems.The image fusion approach accurately represents the three-dimensional distribution of pores and minerals across various scales and supports multiphysics simulations.However,its computational efficiency constrains its ability to manage large-scale discrepancies in hybrid modeling.Conversely,the pore network integration approach allows for modeling across multiple contiguous scales,requires less storage space,and offers high numerical simulation efficiency,although it is limited to certain physical properties.Moreover,digital rock workflows still face challenges,such as the precise extraction of minerals and the determination of suitable representative elementary volumes.Future research should focus on optimizing models using experimental data,studying physical properties as needed,and integrating homogenization and equivalent theory modeling to develop specific application systems that enhance well-logging interpretation and hydrocarbon reservoir development.