Micro-positron emission tomography for measuring sub-core scale single and multiphase transport parameters in porous media
Micro-positron emission tomography for measuring sub-core scale single and multiphase transport parameters in porous media
复制标题
用于测量多孔介质中亚核心尺度单相和多相输运参数的微正电子发射断层扫描
DOI：
10.1016/j.advwatres.2018.03.002
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发表时间：
2018
影响因子：
4.7
通讯作者：
S. Benson
中科院分区：
文献类型：
--
作者：
C. Zahasky;S. Benson
准确描述多孔介质的非均质性对于理解和建模单相（例如污染物迁移、盐水入侵）和多相（例如地质碳储存、提高石油采收率）传输问题非常重要。应用医学成像对这些过程进行实验量化，在实验室规模的材料表征和理解流体传输行为方面取得了重大进展。虽然正电子发射断层扫描（PET）广泛应用于癌症诊断和治疗、心脏病学和神经病学，但在地球科学中的应用相对有限。本研究利用小口径微型 PET 扫描仪对在两个异质伯里亚砂岩岩心中进行单相流和多相流实验期间注入的保守水性放射性示踪剂的脉冲传输行为进行成像和量化。将岩心离散成轴向平行的流管，并使用重建的微型 PET 数据，从空间矩分析中导出表达式，用于计算子岩心示踪剂通量和孔隙水速度。使用通量和速度测量，可以根据体积通量平衡计算孔隙度和饱和度，并根据达西定律计算渗透率和水相对渗透率。第二空间矩分析可以在单相和多相实验中测量子核溶质分散度。开发了数值模拟模型来验证流管降维技术的假设。反应器比率的变化作为诊断指标来有效地确定堆芯和塔规模实验中流管近似的有效性。这项研究引入了一种量化子岩心渗透率、相对渗透率和色散的新方法。这些实验和分析方法为未来跨尺度运输行为差异的实验测量工作奠定了基础。
Accurate descriptions of heterogeneity in porous media are important for understanding and modeling single phase (e.g. contaminant transport, saltwater intrusion) and multiphase (e.g. geologic carbon storage, enhanced oil recovery) transport problems. Application of medical imaging to experimentally quantify these processes has led to significant progress in material characterization and understanding fluid transport behavior at laboratory scales. While widely utilized in cancer diagnosis and management, cardiology, and neurology, positron emission tomography (PET) has had relatively limited applications in earth science. This study utilizes a small-bore micro-PET scanner to image and quantify the transport behavior of pulses of a conservative aqueous radiotracer injected during single and multiphase flow experiments in two heterogeneous Berea sandstone cores. The cores are discretized into axial-parallel streamtubes, and using the reconstructed micro-PET data, expressions are derived from spatial moment analysis for calculating sub-core tracer flux and pore water velocity. Using the flux and velocity measurements, it is possible to calculate porosity and saturation from volumetric flux balance, and calculate permeability and water relative permeability from Darcy’s law. Second spatial moment analysis enables measurement of sub-core solute dispersion during both single phase and multiphase experiments. A numerical simulation model is developed to verify the assumptions of the streamtube dimension reduction technique. A variation of the reactor ratio is presented as a diagnostic metric to efficiently determine the validity of the streamtube approximation in core and column-scale experiments. This study introduces a new method to quantify sub-core permeability, relative permeability, and dispersion. These experimental and analytical methods provide a foundation for future work on experimental measurements of differences in transport behavior across scales.