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在地质流体储存中引力和热扩散传输的方向性
Anna L Herring1, Ruotong Huang2, Adrian Sheppard2
1Civil and Environmental Engineering, <a href="https://ror.org/020f3ap87">University of Tennessee</a>, Knoxville, Tennessee 37996, USA.
Physical review. E
|August 20, 2024
概括
地热梯度扭转了地下二氧化碳和储存的扩散运输方向. 这一发现对这些关键的能源转型技术的长期储存战略产生了影响.
科学领域:
- 地质化学和环境科学
- 储能和地球科学 储能和地球科学
背景情况:
- 二氧化碳 (CO2) 和 (H2) 的地下储存对于减缓气候变化和能源转型至关重要.
- 这些气体存在于多相流体-水-岩石系统中,经历诸如向导,捕获,溶解和扩散等过程.
- 之前对扩散传输的分析往往简化或忽略了非理想气体行为,溶液密度效应和地热梯度下的热扩散.
研究的目的:
- 从热力学第一原理分析地下储存中二氧化碳和二氧化的扩散运输.
- 为了结合非理想性,部分摩尔密度和因地热梯度而产生的热/热扩散效应.
- 在相关地质条件下提供CO2和H2扩散的数值估计.
主要方法:
- 散射运输的热力学第一原理分析.
- 在与地下储存相关的条件下对CO2和H2扩散的数值估计.
- 包括诸如气体非理想性,溶液密度和地热梯度等因素.
主要成果:
- 在同热系统中,二氧化碳和的扩散传输都是向上的.
- 由于地热梯度的热贡献导致两种气体的扩散方向逆转.
- 即使在梯度<10°C/km的情况下,CO2扩散也会向下逆转;在1000米深处的典型梯度下 (例如30°C/km),H2逆转.
- 地热梯度显著改变扩散流量大小,CO2在30°C/km梯度下显示出比H2更大的流量.
- 估计的最大CO2流量为~10^-13mol/(cm^2s),低于高透度构成中的对流流量.
- 扩散和对流可能协同工作:在各自的储存条件下,将CO2向下推,将H2向上推.
结论:
- 地热梯度从根本上改变了地下二氧化碳和气储存的扩散运输的方向和大小.
- 对自由能量的热贡献至关重要,可以逆转扩散方向,独立于溶解物热恐惧性/热友性.
- 为了准确建模二氧化碳和的长期地下储存,对气候缓解和能源转型战略产生影响,需要对扩散传输的理解进行修订.
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