THE IMPACT OF HYDRATE SATURATION ON THE MECHANICAL, ELECTRICAL, AND THERMAL PROPERTIES OF HYDRATE-BEARING SAND, SILTS, AND CLAY
THE IMPACT OF HYDRATE SATURATION ON THE MECHANICAL, ELECTRICAL, AND THERMAL PROPERTIES OF HYDRATE-BEARING SAND, SILTS, AND CLAY
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DOI：
10.1190/1.9781560802197.ch26
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
J. Santamarina;C. Ruppel
中科院分区：
文献类型：
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作者：
J. Santamarina;C. Ruppel
了解含水合物沉积物的物理性质对于解释野外环境中收集的地球物理数据、钻孔和边坡稳定性分析以及油藏模拟和生产模型非常重要。然而，目前的地球物理和岩土工程性质的hydrotearing沉积物的知识仍然主要来自不同的土壤在不同的围压，水饱和度和水合物浓度进行的实验室实验。在这里，我们报告了对沙子、淤泥或粘土合成样本进行5年实验室实验的关键发现，这些样本在标准化土工实验室装置中承受不同的围压，并含有精心控制的由溶解形成的四氢呋喃水合物的饱和度。相。这是第一次，我们使用这个内部一致的数据集进行综合分析的趋势，在地球物理和岩土性能的水合物饱和度，土壤特性和其他参数的函数。我们的实验强调测量地震速度，电导率和介电常数，大应变变形和强度，以及热导率。我们讨论了水合物形成技术对物理性质测量的影响，并使用我们的数据集来识别沉积物特性，水合物浓度和应力状态的系统影响，提取最相关的材料参数的鲁棒关系（通常基于微观力学概念）。对于所测量的物理参数出现的数学趋势总是要求孔隙空间中的水合物饱和度（其范围从0到1）提高到大于1的幂。这显著降低了低水合物饱和度对测量的物理参数的影响，这种影响在许多天然系统的水合物饱和度特征（孔隙空间<0.2）下特别明显。研究结果还表明，含水合物沉积物的电性对实验室水合物形成方法（控制水合物和沉积物颗粒的孔隙尺度排列）的敏感性低于水合物饱和度。力学性能受到土壤性质和水合物位置的强烈影响。热导率取决于各种因素的复杂相互作用，包括形成历史，并且不能通过体积平均公式容易地预测。
An understanding of the physical properties of hydrate-bearing sediments is important for interpretation of geophysical data collected in field settings, borehole and slope stability analyses, and reservoir simulation and production models. Yet current knowledge of geophysical and geotechnical properties of hydratebearing sediments is still largely derived from laboratory experiments conducted on disparate soils at different confining pressures, degrees of water saturation, and hydrate concentrations. Here we report on the key findings that have emerged from 5 years of laboratory experiments conducted on synthetic samples of sand, silts, or clays subjected to various confining pressures in standardized geotechnical laboratory devices and containing carefully controlled saturations of tetrahydrofuran hydrate formed from the dissolved phase. For the first time, we use this internally-consistent data set to conduct a comprehensive analysis of the trends in geophysical and geotechnical properties as a function of hydrate saturation, soil characteristics, and other parameters. Our experiments emphasize measurements of seismic velocities, electrical conductivity and permittivity, large strain deformation and strength, and thermal conductivity. We discuss the impact of hydrate formation technique on the resulting physical properties measurements and use our data set to identify systematic effects of sediment characteristics, hydrate concentration, and state of stress, extracting robust relationships (often based on micromechanical concepts) for the most relevant material parameters. The mathematical trends that emerge for the measured physical parameters always require that the hydrate saturation in pore space, which ranges from 0 to 1, be raised to a power greater than 1. This significantly reduces the impact of low hydrate saturations on the measured physical parameters, an effect that is particularly pronounced at the hydrate saturations characteristic of many natural systems (<0.2 of pore space). The results also reveal that the electrical properties of hydrate-bearing sediments are less sensitive to the method used to form hydrate in the lab (which controls the pore-scale arrangement of hydrate and sediment grains) than to hydrate saturation. Mechanical properties are strongly influenced by both soil properties and the hydrate loci. Thermal conductivity depends on the complex interplay of a variety of factors, including formation history, and cannot be easily predicted by volume average formulations.