NUMERICAL STUDY OF FRACTURE APERTURE CHARACTERISTICS AND THEIR IMPACT ON SINGLE-PHASE FLOW AND CAPILLARY-DOMINATED DISPLACEMENT
NUMERICAL STUDY OF FRACTURE APERTURE CHARACTERISTICS AND THEIR IMPACT ON SINGLE-PHASE FLOW AND CAPILLARY-DOMINATED DISPLACEMENT
复制标题
DOI：
--
复制
发表时间：
2008-03
影响因子：
5.2
通讯作者：
T. Petchsingto
中科院分区：
文献类型：
--
作者：
T. Petchsingto
裂隙地质地层中非混相渗流的一般问题在水文学、地热开采、地下污染环境修复和油气开采等应用中得到了广泛的研究。油气藏的采收率受储集岩中天然裂缝的存在有很大影响。在天然裂缝性油藏中，裂隙网络为流体的流动提供了有利的路径，而多孔岩石提供了储存空间。裂缝中非混相流动研究中经常遇到的两个困难是裂缝的几何表示，以及代表裂缝不规则表面与流体之间复杂相互作用的整体裂缝流动特性的赋值。这项研究的目的是考察单相和两相毛细管主导的驱替。使用商用计算流体力学软件对单相流进行了研究。开发了一个基于物理的渗流模型来研究毛细管主导的驱替，并以Karpyn等人(2007)的实验工作为模型参考进行了验证。阐述了裂缝结构特征、优先流道与裂缝毛管压力曲线之间的对应关系，为利用裂缝孔径参数预测裂缝毛管压力提供了一种方法。根据计算机断层扫描(CT)测量的骨折的详细描述的知识被用于生成真实的骨折复制品。利用计算流体动力学(CFD)模拟技术，对CT扫描的裂缝进行了单相流模拟。通过对真实裂隙中流动的压力等值线和速度矢量分布的可视化，探讨了裂隙粗糙度和路径曲折的影响。CFD模拟的结果与使用理想化光滑骨折或平行板模型的预测进行了比较。明显的差异表明，由于缺乏真实裂缝的有效物理表示，立方定律不足以描述裂缝中的流动。的偏差
The general problem of immiscible flow in fractured geologic formations has been studied extensively in applications such as hydrology, geo-thermal exploitation, environmental remediation of subsurface contamination, and hydrocarbon recovery. Recovery from oil and gas reservoirs is greatly affected by the presence of natural fractures in the reservoir rock. In naturally fractured reservoirs, the fracture network provides preferential paths for fluids to flow, while the porous rock provides the storage space. Two often encountered difficulties in the study of immiscible flow in fractures are the geometric representation of these fractures, and assigning bulk fracture flow properties representing the complex interactions between the irregular surface of the fractures and the fluids. The objective of this study is to examine both single-phase and two-phase capillary-dominated displacements. A commercially available computational fluid dynamics software was used to investigate single-phase flow. A physically-based percolation model was developed to study capillary-dominated displacement, and validated by using experimental work of Karpyn et al., (2007) as a modeling reference. This study elaborates on the correspondence between structural characteristics of fractures, preferential flow channeling and fracture capillary pressure curves, thus providing a methodology to predict fracture capillary pressure from fracture aperture parameterization. Knowledge of detailed descriptions of a fracture from Computed Tomography (CT) measurement was used for generating a realistic fracture replica. Single-phase flow simulations were carried out on the CT-scanned fracture by means of Computational Fluid Dynamics (CFD) simulation. The effects of fracture roughness and path tortuosity were explored by visualizations of pressure contours and vector velocity profiles of flows thorough the realistic fracture. The results of CFD simulations were compared against predictions using idealized smooth fractures or parallel plate models. Noticeable discrepancies showed that the cubic law was inadequate in describing flows in fractures because of lack of a valid physical representation of a real fracture. The deviations of