Quantifying the Anisotropy of Permeability in Stressed Rock

量化受力岩石渗透率的各向异性

• 批准号: NE/N003063/1
• 负责人: David Healy
• 金额: $ 46.86万
• 依托单位: University of Aberdeen
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FN003063%2F1
• 关键词: Quantifying; Anisotropy; Permeability; Stressed; Rock

Fluid flow in rocks is vitally important for a wide range of natural processes and human activities, including the triggering of earthquakes, the extraction of oil, gas and water from subsurface reservoirs, and the storage of waste products such as CO2 or radioactive waste. Fluid flow in the Earth's crust takes place through connected networks of pores, cracks and fractures, and is driven by differences in fluid pressure. We measure the ability of rocks to conduct fluid as permeability, and rocks are known to exhibit strong directional variations - or anisotropy - of this key transport property. Laboratory experiments and in situ borehole tests have shown that permeability can vary by several orders of magnitude - i.e. by factors of 100 or 1000 - in different directions. Permeability is also known to be highly dependent on the stress in the solid rock matrix. Again, finely controlled laboratory tests and rather less well constrained in-situ measurements from the subsurface show this to be the case. A key problem though is that the laboratory tests conducted to date have been conducted under simplified stress conditions which do not match the actual anisotropy of in situ stress within the crust. This makes it very difficult to interpret and apply the published laboratory data to more general geological situations, such as fluid flow around seismically active fault zones or reducing risks for CO2 storage in fractured porous reservoirs, with any degree of confidence. Our proposal is to use a new apparatus at UCL which can apply fully anisotropic (truly triaxial) stress to fluid saturated rock samples of sandstone and granite. Cubic or rectangular shaped blocks of rock will be compressed by three pairs of metal rams, symmetrically arranged at 90 degrees to each other around the sample. This will allow us to vary each of the 3 main (principal) stresses independently. Rock samples will be large enough (5 x 5 x 5 cm cubes, for example) to contain quasi-homogeneous distributions of pores and cracks. We will modify this unique apparatus to enable measurement of permeability along any of the three loading directions that compress the rock. Our proposal builds on recent award-winning research at Aberdeen, where permeability anisotropy has been measured in on oriented samples from a natural fault zone, and carefully related to the pore fabric within the rock. We aim to link the anisotropy of permeability with the anisotropy of stress and the anisotropy of the void space (= pores + cracks). We will define new empirical equations from our quantitative laboratory tests and porosity characterisations. These data and relationships will be used in state-of-the-art computer models of fault zones to explore how directional variations in fluid flow (permeability anisotropy) affect the probability and the type of slip events expected along a fault zone. This will provide a much improved understanding of the risks from earthquake-prone faults in the crust, and more generally, we will begin to understand the truly 3D nature of fluid flow in rocks.

岩石中的流体流对广泛的自然过程和人类活动至关重要，包括触发地震，从地下储层中提取油，天然气和水以及储存二氧化碳或放射性废物等废物的存储。地壳中的流体流通过连接的毛孔，裂缝和断裂的网络进行，并由流体压力差异驱动。我们测量岩石将流体作为渗透性的能力，并已知岩石表现出强烈的方向变化（或各向异性）。实验室实验和原位井眼测试表明，渗透率可能会因不同方向上的几个数量级而变化，即通过100或1000的因子。渗透性也高度依赖于固体岩石基质中的应力。同样，从地下进行精心控制的实验室测试，相当不太约束的原位测量结果表明是这种情况。但是，一个关键问题是，迄今为止进行的实验室测试是在简化的应力条件下进行的，这些条件与地壳内原位应力的实际各向异性不符。这使得很难解释并将已发布的实验室数据应用于更一般的地质情况，例如围绕地震活跃断层区域周围的流体流量或以任何信心降低断裂多孔储层中的二氧化碳储存风险。我们的建议是在UCL上使用新的设备，该设备可以将完全各向异性（真正的三轴）应力施加到砂岩和花岗岩的流体饱和岩石样品中。三对金属公羊将压缩岩石的立方体或矩形形状的块，在样品周围以90度的对称排列。这将使我们能够独立改变3个主要（原理）强调。岩石样品将足够大（例如，5 x 5 x 5 cm立方体），以包含孔和裂纹的准均匀分布。我们将修改这种独特的设备，以沿着压缩岩石的三个加载方向中的任何一个启用渗透率。我们的提案建立在最近在阿伯丁获奖研究的基础上，在阿伯丁屡获殊荣的研究中，在自然断层区的定向样品中测量了各向异性，并与岩石内的孔隙织物进行了认真的关系。我们的目的是将渗透率各向异性与应力和空隙空间的各向异性（=孔 +裂纹）联系起来。我们将通过定量实验室测试和孔隙率特征来定义新的经验方程。这些数据和关系将用于故障区域的最新计算机模型中，以探讨流体流动流动（渗透率各向异性）如何影响沿断层区域沿线预期的损益和预期的滑移事件的类型。这将提供对地壳中地震易于地震断层的风险的大大提高的理解，更普遍地，我们将开始理解岩石中流体流动的真正3D性质。

项目成果

Anisotropic pore fabrics in faulted porous sandstones

• DOI: 10.1016/j.jsg.2017.09.010
• 发表时间: 2017-11-01
• 期刊: JOURNAL OF STRUCTURAL GEOLOGY
• 影响因子: 3.1
• 作者: Farrell, N. J. C.;Healy, D.
• 通讯作者: Healy, D.

Bimodal or quadrimodal? Statistical tests for the shape of fault patterns

双峰还是四峰？

• DOI: 10.31223/osf.io/v6r28
• 发表时间: 2018
• 作者: Healy D

Acoustic characterization of crack damage evolution in sandstone deformed under conventional and true triaxial loading

• DOI: 10.1002/2016jb013646
• 发表时间: 2017-06-01
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
• 影响因子: 3.9
• 作者: Browning, J.;Meredith, P. G.;Mitchell, T. M.
• 通讯作者: Mitchell, T. M.

The Effect of Authigenic Clays on Fault Zone Permeability

自生粘土对断裂带渗透性的影响

• DOI: 10.1029/2021jb022615
• 发表时间: 2021
• 期刊: Solid Earth
• 影响因子: 3.4
• 作者: Farrell N

FracPaQ: A MATLAB™ toolbox for the quantification of fracture patterns

• DOI: 10.1016/j.jsg.2016.12.003
• 发表时间: 2016-12
• 期刊: Journal of Structural Geology
• 影响因子: 3.1
• 作者: D. Healy;R. Rizzo;D. Cornwell;N. Farrell;Hannah Watkins;N. Timms;E. Gomez‐Rivas;Michael C. Smith-Michael-C.-Sm