Fiber Optic Distributed Acoustic Sensing for Stress Measurement and Mitigation of High Stress Hazards at Depth

在岩石工程设计中，地下深层存在的应力状态是最重要的输入之一。它决定了许多重要的决定，如地热和非常规天然气开发的水平井的最佳方位，以及为确保安全而进行的采矿、水电大坝和核废料储存库的地下开挖的方位、尺寸和支持。然而，尽管它很重要，但它也是岩石工程设计中最难可靠测量的参数。这导致了许多应力测量技术的开发，每一种技术都有很大的局限性和可靠性问题。光纤传感能力的出现提供了几个优势，这些优势有可能克服这些挑战并带来重要的改进。为此，需要一个分布式声学传感(DAS)光纤测试系统，以允许推进创新所需的实验室规模的实验，以开发一种新的光纤应力测量技术。该设备的增加将允许独立的台式测试，以及与现有最先进的岩石测试系统的集成，该系统能够再现深部采矿和能源开发项目中遇到的应力、温度和流体压力条件。这将使我们能够支持我们的其他研究计划和学生培训，重点是提高安全和减少与这些活动相关的危险。 这项研究的重要性直接关系到加拿大的经济，以及为我们的采矿和能源部门培训下一代工程师和地球科学家。例如，几个加拿大煤矿正在接近3000米深的地方，这使它们面临着以岩爆形式存在的高应力危险。这具有重大的安全影响，可能会影响这些矿山的经济可行性，特别是在这些深度应力测量的可靠性得不到改善的情况下。加拿大的核废料管理计划现在正在寻找一个具有满足安全要求所需的地质条件的深层储存库的地点。评估现有的应力和岩石破坏的可能性对于确保围岩达到其预期的目的至关重要，即充当防止水进入和废物外泄的低渗透性屏障。为使加拿大非常规气藏能够生产而进行的水力压裂作业，一直受到公众和监管机构对诱发地震活动的担忧。在我们对断层滑动机制和控制诱发地震活动的可能性和强度的因素的理解方面的知识差距加剧了这一点。本提案中要求的实验设备将使我们能够描绘与脆性岩石变形和破坏相关的应力和应变模式，从而帮助我们加快应对这些挑战的研究计划。

The stress conditions present in the ground at depth are one of the most important inputs in rock engineering design. It dictates many important decisions such as the optimal orientation of horizontal wells for geothermal and unconventional gas development, as well as the orientation, dimensioning and support of underground excavations for mining, hydroelectric dams and nuclear waste repositories to ensure safety. Yet despite its importance, it is also the most difficult parameter in rock engineering design to reliably measure. This has led to numerous stress measurement techniques being developed, each with significant limitations and reliability issues. The emergence of fiber optic sensing capabilities offers several advantages that have the potential to overcome these challenges and add important improvements. For this, a Distributed Acoustic Sensing (DAS) fiber optic testing system is being requested to allow lab-scale experiments required to advance innovation to develop a new fiber optic stress measurement technique. The addition of this equipment will allow for stand-alone benchtop testing as well its integration with an existing state-of-the-art rock testing system capable of reproducing the stress, temperature and fluid pressure conditions encountered on deep mining and energy development projects. This will allow us to support our other research programs and student training focussed on improving safety and mitigating hazards related to these activities. The importance of this research is of direct relevance to Canada's economy, as well as the training of the next generation of engineers and geoscientists for our mining and energy sectors. For example, several Canadian mines are approaching depths of 3000 m exposing them to high stress hazards in the form of rockbursting. This has significant safety implications that could impact the economic viability of these mines, especially without improvements in the reliability of stress measurements at these depths. Canada's nuclear waste management program is now searching for a site for a deep repository with the geological conditions necessary to satisfy safety requirements. Assessing the stresses present and potential for rock failure is essential to ensure that the host rock serves its intended purpose of acting as a low permeability barrier to prevent the ingress of water and escape of waste. Hydraulic fracturing operations to enable production from Canada's unconventional gas reservoirs have been subject to public and regulator concerns regarding induced seismicity. These are heightened by knowledge gaps in our understanding of fault slip mechanisms and the factors controlling the likelihood and magnitude of induced seismicity. The experimental equipment being requested in this proposal will help us to accelerate our research programs addressing these challenges by allowing us to image the stress and strain patterns associated with brittle rock deformation and failure.