Modeling Flow in Porous Media with Vugular Meso-scale Heterogeneities

具有脆弱介观尺度异质性的多孔介质中的流动建模

• 批准号: 0074310
• 负责人: Todd Arbogast
• 金额: $ 24万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2004-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0074310&HistoricalAwards=false
• 关键词: Modeling; Flow; Porous; Media; Vugular

Arbogast0074310 Sedimentary rocks sometimes contain void regions called vugs that are much larger than the usual intergranular pores. Vugular heterogeneities raise both practical and theoretical problems for understanding fluid flow through such rocks at the field scale. For example, standard sampling methods are at a scale too small to resolve these heterogeneities. Moreover it is nontrivial to identify the correct physical formalism for modeling flow or interpreting flow measurements, and it is not clear that traditional homogenization approaches are applicable. In this project, the investigators tie microscopic (CT scan) and macroscopic measurements of a large sample (about 17,000 cubic cm) of Cretaceous carbonate rock containing centimeter-scale vugs directly to high-resolution computation of flow fields. This framework allows the testing of different physical models for flow in the geometry of the sample. The specific objectives are to: (1) Map CT scan pixels of the sample to permeability and porosity; (2) Simulate flow in the micro-scale system; (3) Determine the macro-scale governing relations for single phase flow; and (4) Determine the macroscopic model parameters in terms of the microscale characterization. Research in algorithms and upscaling procedures is conducted to achieve the second and third objectives. Subsequent numerical experiments determine the influence of alternative depositional environments and diagenetic histories by changing the connectivity of the vugs and the permeability distribution of the matrix material. This results finally in the ability to more confidently predict flow in vugular media in full-field simulations. The flow of fluids through porous rock is of economic and environmental interest. Examples include oil and gas production, obtaining adequate water supplies (groundwater accounts for about one third of the water used in the US, with many cities depending exclusively on wells), and remediating subsurface contamination at Superfund sites and many Department of Energy facilities. The sedimentary rocks through which these flows occur sometimes contain relatively large holes or void regions called vugs. The dissolution of fossil fragments is a common mechanism for creating vugs in carbonate rocks, which contain more than half the world's oil reserves and comprise many of the biggest aquifers in the US. Vugs are more conducive to fluid flow than the much smaller pore space between the rock grains, and this raises both both practical and theoretical problems for understanding large-scale flows. This project aims to construct models for this type of rock that predict the effective flow properties over hundreds of yards to several miles. Because direct experimentation over these distances is not feasible, an essential component of the research is the integration of intermediate-scale physical and large-scale computational experiments. This effort also relies on basic research in numerical algorithms and modeling techniques. Establishing the correct relations governing the flow of fluids in such rocks enables more confident predictions from full-field simulations.

沉积岩有时含有称为孔洞的空隙区，它们比通常的粒间孔隙大得多。空穴非均质性为在野外尺度上理解流体流过此类岩石提出了实际和理论问题。例如，标准抽样方法的规模太小，无法解决这些异质性。此外，确定正确的物理形式来模拟流动或解释流动测量结果是非常重要的，并且不清楚传统的均质方法是否适用。在这个项目中，研究人员将白垩纪碳酸盐岩大样本（约17000立方厘米）的微观（CT扫描）和宏观测量直接与流场的高分辨率计算相结合。该框架允许在样品的几何形状中测试不同的流动物理模型。具体目标是：(1)将样品的CT扫描像元映射为渗透率和孔隙度；(2)模拟微尺度系统的流动；(3)确定单相流宏观调控关系；(4)从微观表征角度确定宏观模型参数。为了实现第二个和第三个目标，对算法和升级程序进行了研究。随后的数值实验通过改变孔隙的连通性和基质物质的渗透率分布来确定不同沉积环境和成岩历史的影响。这最终使我们能够在全场模拟中更自信地预测空化介质中的流动。流体在多孔岩石中的流动具有经济和环境意义。例子包括石油和天然气生产，获得充足的水供应（地下水约占美国用水量的三分之一，许多城市完全依赖水井），以及修复超级基金场址和许多能源部设施的地下污染。这些水流流经的沉积岩有时含有相对较大的孔洞或称为洞穴的空隙区。化石碎片的溶解是在碳酸盐岩中形成洞穴的一种常见机制，碳酸盐岩蕴藏着世界上一半以上的石油储量，并构成了美国许多最大的含水层。与岩石颗粒之间小得多的孔隙空间相比，孔洞更有利于流体流动，这为理解大规模流动提出了实际和理论问题。该项目旨在为这类岩石建立模型，以预测数百码到几英里范围内的有效流动特性。由于在这些距离上进行直接实验是不可行的，因此研究的一个重要组成部分是将中等规模的物理实验和大规模的计算实验结合起来。这项工作还依赖于数值算法和建模技术的基础研究。建立控制此类岩石中流体流动的正确关系，可以从全场模拟中得到更有信心的预测。