3D Experimental and Computational Studies of Crystallographic Effects on Creep and Fracture in Salt Rock

晶体学对盐岩蠕变和断裂影响的 3D 实验和计算研究

基本信息

批准号：
1641054
负责人：
Khalid Alshibli
金额：
$ 33.16万
依托单位：
University of Tennessee Knoxville
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-10-01 至 2021-09-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1641054&HistoricalAwards=false
关键词：
3D Experimental Computational Studies Crystallographic

项目摘要

Rock salt, a sedimentary rock classified as an evaporate, forms as a result of evaporation of inland seas or any enclosed body of water, and can be found in nature as bedded or domal formations. Salt domes often trap oil, gas, and other minerals around their edges. Salt caverns are large cavities or chambers that form inside underground salt deposits either naturally by the effect of geological processes or are man-made. They have been used as storage for different types of hydrocarbons since early 1970s including the US strategic petroleum reserve. Salt caverns may potentially serve as a long-term and safe repository for carbon dioxide, nuclear waste, and the waste of oil drilling operations. Drilling through rock salt poses many challenges, including long-term wellbore stability/integrity, casing collapse due to lateral pressure, and drilling fluid-salt interaction. The accuracy with which the fracture behavior of any material can be simulated, including geological materials like rock, hinges upon the fidelity of both the engineering model and the geometrical representation of the cracked body. The anisotropic response of rock salt during creep deformations is stress and temperature dependent, and the accumulated creep strain influences fracture nucleation. This behavior creates many challenges when rock salt formations interact with sources of thermal and stress changes. An improved and quantitative understanding of when, where, and how cracks evolve within 3D polycrystalline rocks has many important technological implications with potential benefits for modeling drilling, geothermal-energy extraction, carbon sequestration, machine-rock interaction, and explosive penetration. This project (i) impacts the research community and promotes technology transfer; (ii) involves minority/female undergraduate students in conducting cutting-edge engineering research; and (iii) engages the next generation of scientists through the involvement of high school students in research, sparking their interest in the field of civil engineering and helping contribute to the quality of the next generation of civil engineering educators and professionals.A key limitation of existing phenomenological creep models is that rock salt's anisotropic response is not represented at the microstructural level. While crystal plasticity models for capturing anisotropy in rock salt do exist, they employ empirical flow rate equations which are valid for a narrow range of temperature and strain rate. Presently, there is an apparent lack of crystal-orientation-sensitive models in the literature for creep and fracture in 3D rock specimens coupled with direct measurements of 3D crystal structure. Thus, this research will combine nondestructive 3D x-ray diffraction (3DXRD), 3D synchrotron micro-computed tomography (SMT) in-situ experimental measurements, and 3D crystal-plasticity modeling to enhance current understanding of creep and crack formation and growth mechanisms in polycrystalline rock is unprecedented in many regards. The ability to experimentally measure lattice strains within the microstructure of rock has recently been demonstrated by the PI. These enhanced experimental techniques provide us with a richer dataset for calibrating the microstructural constitutive model accounting for anisotropy. By employing dislocation mechanism-based crystal plasticity models, we plan to elucidate the governing mechanisms operating in the halite crystals that yield the observed creep and fracture response.

岩盐是一种蒸发的沉积岩石，是由于内陆海洋或任何封闭的水体蒸发而形成的，可以在自然界中以卧床或domal地层的形式找到。盐圆顶经常将油，天然气和其他矿物质缠绕在其边缘。盐洞是大型腔或腔室，它们在地下盐沉积物内部由地质过程的影响自然或人为形成。自1970年代初以来，它们已被用作不同类型的碳氢化合物的存储空间，包括美国战略石油储备。盐洞可能有可能作为二氧化碳，核废料和石油钻井作业的长期安全存储库。通过岩盐钻探构成了许多挑战，包括长期的井眼稳定性/完整性，由于横向压力而导致的外壳崩溃以及钻孔液 - 盐相互作用。可以模拟任何材料的断裂行为的准确性，包括岩石等地质材料，取决于工程模型的保真度和破裂体的几何表示。蠕变变形过程中岩盐的各向异性反应是应力和温度依赖性，而累积的蠕变应变会影响断裂成核。当岩盐形成与热量变化的来源相互作用时，这种行为会带来许多挑战。对3D多晶岩中何时，何地和如何发展的改进和定量理解具有许多重要的技术意义，具有模拟钻孔，地热能提取，碳固化，机器摇滚相互作用和爆炸性渗透的潜在益处。该项目（i）影响研究界并促进技术转移；（ii）涉及少数民族/女本科生进行尖端的工程研究；（iii）通过高中生参与研究，激发他们对土木工程领域的兴趣，并帮助下一代土木工程教育者和专业人士的质量，参与下一代科学家。现有的现象学蠕变模型是，岩盐的各向异性反应在微观结构层没有表示。尽管确实存在用于捕获岩盐各向异性的晶体可塑性模型，但它们采用经验流量方程，这些方程在狭窄的温度和应变速率范围内有效。目前，在3D岩石标本中的蠕变和断裂以及3D晶体结构的直接测量值中，文献中显然缺乏晶体取向敏感的模型。因此，这项研究将结合非损坏的3D X射线衍射（3DXRD），3D同步型微型计算机扫描（SMT）实验测量值和3D晶体塑性模型，以增强对蠕变和裂纹形成和裂纹形成和裂纹形成和生长机制的理解在许多方面，多晶岩是前所未有的。 PI最近证明了岩石微结构内实验测量晶格菌株的能力。这些增强的实验技术为我们提供了一个更丰富的数据集，用于校准对各向异性的微观结构组成模型。通过采用基于脱位机制的晶体可塑性模型，我们计划阐明在Halite晶体中运行的管理机制，从而产生观察到的蠕变和断裂反应。