Injection Induced Seismicity in Hot Resevoirs

热油藏中的注入诱发地震活动

• 批准号: 1534903
• 负责人: Steven Glaser
• 金额: $ 35.65万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1534903&HistoricalAwards=false
• 关键词: Injection; Induced; Seismicity; Hot; Resevoirs

Enhanced geothermal systems are potentially a major contributor to the nation's supply of clean, sustainable energy. An enhanced geothermal reservoir is an engineered subsurface heat exchanger designed to improve a conventional hydrothermal reservoir, or to create a circulation system where hot reservoir rocks have low permeability. This is most often done by injection of pressurized fluids. This injection has been shown to induce seismicity. Understanding why injection-induced seismicity occurs is fundamental for utilizing this resource. Understanding the mechanisms of induced seismicity is also necessary for the exploitation of the country's rich deposits of shale gas, and for carbon sequestration. Because the in situ mechanisms of injection induced seismicity are so complex, there still is a lack of deep understanding. The project will carry out a set of experiments in very specialized equipment that can model the Geysers geothermal field. This will bring the understanding needed to engineer for the mechanisms behind induced seismicity so that subsurface injection of fluids for energy resources can be used without causing earthquakesThe project is based on a carefully designed sequence of tests, each informing the next. The first stage is the investigation of the effects of fault unloading vs. increased shear loading on foreshocks and rupture. Preliminary work by Glaser shows that the dynamics are quite different. These experiments will take place in a laboratory earthquake machine. The next set of experiments will take place in the Glaser lab's true-triaxial geothermal reservoir simulator. Integral to this device is a high pressure boiler that floods 250 mm cubes of rock with 2 MPa steam, duplicating the Geysers field. Specimens will be fractured to represent a rock mass rather than a solid cube of rock. We will investigate the effects of thermal contraction, and injected water flashing to steam, as proximate causes of fault weakening. Both through-going and growing hydraulic fractures will be modeled. The dynamic asperity-level displacement "seeds" that lead to macro-rupture will be studied through nano-seismic imaging. This is made possible by absolutely-calibrated nanoseismic sensors, which have a noise floor of 0.2 pm. Over many years, laboratory analysis methodologies have been developed based on tools used by seismologists, to accurately measure absolute metrics of rupture kinematics, including the source-time function to mN sensitivity. Because similar tools are used to study seismicity at the Geysers, it is possible to reasonably scale our results.

增强的地热系统可能是该国清洁，可持续能源供应的主要贡献者。 增强的地热储层是一种工程的地下热交换器，旨在改善传统的热液储层，或者创建一个循环系统，在该系统中，热储层岩石的渗透性较低。 这通常是通过注入加压液来完成的。 该注射已显示出诱导地震性。了解为什么会导致的地震性发生是利用此资源的基础。 了解诱导的地震性的机制对于剥削该国丰富的页岩气和碳固换也是必要的。 由于注射诱发的地震性的原位机制是如此复杂，因此仍然缺乏深刻的理解。 该项目将在非常专业的设备中进行一系列实验，这些设备可以对间歇泉地热场进行建模。 这将为诱导地震性背后的机制提供所需的理解，以便可以使用地下注入能源资源的流体，而不会导致地震项目基于经过精心设计的一系列测试序列，每个测试序列都告知了下一个测试。 第一阶段是研究断层卸载的影响与增加剪切负荷对前壳和破裂的影响。 格拉瑟（Glaser）的初步工作表明，动力学大不相同。 这些实验将发生在实验室地震机中。 下一组实验将发生在Glaser Lab的真实三轴地热储层模拟器中。该设备不可或缺的是一个高压锅炉，该锅炉泛滥250毫米立方体，带有2 MPA蒸汽，重复了Geysers Field。标本将破裂以表示岩石质量，而不是坚固的岩石立方体。 我们将研究热收缩的影响，并将水闪到蒸汽中闪烁，这是故障削弱的近端原因。 贯穿液压骨折的过程和生长都将被建模。 将通过纳米视觉成像研究导致宏爆发的动态阳离子级位移“种子”。 绝对校准的纳米震动传感器使噪声底部为0.2 pm使这成为可能。 多年来，基于地震学家使用的工具，已经开发了实验室分析方法，以准确测量破裂运动学的绝对指标，包括源时间函数到MN敏感性。 由于类似的工具用于研究间歇泉的地震性，因此有可能合理地扩展我们的结果。