Laboratory Controlled Experiments of Rock Fracture and Induced Seismicity

岩石破裂与诱发地震室内控制实验

• 批准号: RGPIN-2016-05710
• 负责人: Young, RPaul
• 金额: $ 2.4万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709933
• 关键词: Laboratory; Controlled; Experiments; Rock; Fracture

Fractures are important at all scales in nature from mineral grain micro-cracks to tectonic plate boundaries. They create earthquakes, control fluid flow and at the engineering scale reduce the integrity of rock around underground structures. The recording of earthquakes on sensors all around the earth has allowed seismologists to create detailed images of the internal structure of the earth. In a similar way, it is possible to listen to small scale induced fracturing in the laboratory under controlled conditions and use the same seismology techniques with high frequency sensors to image the growth of fractures and monitor their effect on rock deformation and fluid flow. This research will utilize a novel rock deformation apparatus that can simulate the three independent stresses that exist in the earth and deform samples of rock at elevated temperatures and fluid pressure. The samples are contained in a pressure vessel that uses high frequency listening devices to monitor the creation of fractures by locating laboratory earthquakes. The pressure vessel also facilitates repeated ultrasonic imaging as the samples are deformed to failure. The rate and viscosity of fluid injection can be controlled, and measurements of permeability are possible through out the deformation tests. Pre and post testing X-ray CT scans and petrofabric analysis are used together with ultrasonic imaging during the tests for the interpretation and validation of the seismic and deformation results. In parallel, numerical models appropriate to fracturing in rock are used to model the same tests and provide a method for extending interpretations to new scenarios. The research will focus on two areas of environmental concern where controlled laboratory experiments can enhance our understanding of the processes and what controls them. The first is fluid injection of wastewater from hydraulic fracturing which can trigger felt earthquakes or bring forward in time what may have happened by natural processes. Controlled experiments of fluid injection in the laboratory, on created fractures, will be used to study the interaction of microcracking and larger fractures that slip when triggered by fluid and deformation processes. The second area is the effect of 3D loading and unloading history, induced by the creation of excavations, on the strength and behavior of fractured rock. Here, in situ stress, deformation and seismic data from Underground Research Laboratories, built to study deep geological disposal of radioactive waste (Canada, Sweden and Finland), will be used to design the 3D loading path in the pressure vessel to simulate the deformation history of rock in excavation damage zones surrounding underground openings. Results at both scales will be used to validate numerical models of fracturing and fluid flow processes and contribute to understanding how these processes scale from the laboratory to in situ conditions.

裂缝在自然界中的所有尺度上都很重要，从矿物颗粒微裂缝到构造板块边界。 它们制造地震，控制流体流动，并在工程规模上降低地下结构周围岩石的完整性。地震传感器在地球上的记录使地震学家能够创建地球内部结构的详细图像。以类似的方式，可以在受控条件下在实验室中收听小规模的诱导压裂，并使用具有高频传感器的相同地震学技术来对裂缝的生长进行成像，并监测其对岩石变形和流体流动的影响。 这项研究将利用一种新型的岩石变形装置，该装置可以模拟地球中存在的三种独立应力，并在高温和流体压力下使岩石样品变形。这些样本被装在一个压力容器中，该容器使用高频监听设备通过定位实验室地震来监测裂缝的产生。压力容器还有助于在样品变形至失效时重复超声成像。 可以控制流体注入的速率和粘度，并且可以通过变形试验测量渗透率。测试前后的X射线CT扫描和岩石组构分析与超声波成像一起用于地震和变形结果的解释和验证。与此同时，适用于岩石破裂的数值模型用于模拟相同的测试，并提供了一种将解释扩展到新场景的方法。 该研究将集中在两个环境问题领域，其中受控实验室实验可以提高我们对过程的理解以及控制它们的因素。第一种是水力压裂产生的废水的流体注入，这可以触发有感地震或及时提出自然过程可能发生的事情。在实验室中对产生的裂缝进行流体注入的受控实验，将用于研究微裂纹和较大裂缝的相互作用，这些裂缝在流体和变形过程触发时发生滑动。第二个领域是三维加载和卸载历史的影响，诱导的创造挖掘，对强度和行为的破碎岩石。在这里，在原地应力，变形和地震数据从地下研究实验室，建立了研究放射性废物的深地质处置（加拿大，瑞典和芬兰），将被用来设计三维加载路径的压力容器，以模拟岩石的变形历史挖掘破坏区周围的地下开口。两种规模的结果将用于验证压裂和流体流动过程的数值模型，并有助于了解这些过程如何从实验室扩展到现场条件。