Microseismic impact assessment for shale-gas stimulation (MIA)

页岩气增产微震影响评估（MIA）

• 批准号: NE/L008351/1
• 负责人: Michael Kendall
• 金额: $ 11.53万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FL008351%2F1
• 关键词: Microseismic; impact; assessment; shale; gas

Hydraulic stimulation - where fluids are injected at high pressure into rocks to create the fractures needed to produce hydrocarbons from 'tight' (low permeability) rocks - is currently the fastest growing sector of the oil and gas industry. Shale gas exploitation has been an economic game changer in the USA. It has been estimated that the USA could be energy self-sufficient by 2050 and the country has reduced its CO2 emissions substantially, as shale gas is displacing coal as a fuel. Coal has once again become Britain's dominant fuel for electricity, and Europe is now importing coal from the USA. Hence there is considerable interest in exploiting cleaner shale gas. Nevertheless, these activities are not without controversy. It has long been known that subsurface fluid injection has the potential to trigger seismic events. As well as the direct hazard posed by seismic activity, reactivated faults may provide a hydraulic connection from the reservoir to the surface, leading to concerns about aquifer contamination and surface leakage. Here we propose a long-term seismic strategy to monitor induced seismicity and guide the mitigation of the risks it may pose.Passive seismic monitoring refers to detecting very small earthquakes or microseismicity. Many anthropogenic activities can create microseismic events (earthquakes with magnitudes between -2.0 to -4.0, which release the energy equivalent of dropping a gallon of milk from a kitchen counter). Such events hold the telltale signs of fracture network development and where fluids are migrating, providing potential early warning signs of any breach in caprock integrity. Furthermore, these activities can sometimes trigger much larger events (such as the recent M2.3 event in Lancashire). Although events of such magnitude are unlikely to cause significant damage, they represent a source of concern for local populations. Bristol University has been doing research in this area for the past 10 years and is ahead of the curve in technology, as the industry norm is to simply locate events. We have developed a suite of software that characterises the seismic source, monitors fracture network development, and holds the potential to track fluid migration through the subsurface in semi-real-time. The Bristol University Microseismicity Projects (BUMPS) project is a joint-industry-project (JIP) sponsored by 8 oil and gas companies. Entering into its third phase, the focus has shifted from technique development to answering key questions facing operators in unconventional resource plays. The proposed catalyst funding will broaden the scope of the project to include environmental impact monitoring. Sparse seismic networks can be used to monitor induced seismicity in shale gas regions. Under the current 'traffic-light' system, operational decisions will be taken based on events with magnitudes of 0.0 - 0.5. Accurate and independent estimates of induced event magnitudes are therefore required. To do so robustly is a challenging task for events of such low magnitudes and current UK seismic catalogues are only complete to magnitude 2.0. Therefore, baseline surveys of seismicity that are complete down to these low magnitudes will be needed if we are to unambiguously determine the cause of any events detected during and following stimulation activities. We will deploy a sparse network of seismometers in a region of current gas exploration in the UK (see letter of support). Such networks provide an independent estimate of event magnitude, information that is needed for 'traffic-light' monitoring of induced seismicity. It is important for regulatory purposes and public confidence that such a seismic network is established and operated by institutions independent from the oil and gas operators. To this end, we will develop a set of best practice guidelines for environmental impact monitoring of shale gas stimulation.

水力吞吐是目前油气行业增长最快的领域。水力吞吐是指在高压下将流体注入岩石，以形成从致密(低渗透率)岩石中生产碳氢化合物所需的裂缝。页岩气开采已经成为美国经济游戏规则的改变者。据估计，随着页岩气正在取代煤炭作为燃料，美国到2050年可能实现能源自给自足，而且该国已经大幅减少了二氧化碳排放。煤炭再次成为英国主要的电力燃料，欧洲现在正从美国进口煤炭。因此，人们对开发更清洁的页岩气有相当大的兴趣。然而，这些活动并非没有争议。地下流体注入具有触发地震事件的潜力，这一点早已为人所知。除了地震活动造成的直接危险外，重新激活的断层可能提供从水库到地表的水力连接，导致人们对含水层污染和地表渗漏的担忧。在这里，我们提出了一种长期的地震战略，以监测诱发地震活动并指导减轻其可能带来的风险。被动地震监测是指检测极小地震或微震活动。许多人为活动都可能产生微震事件(震级在-2.0到-4.0之间的地震，其释放的能量相当于从厨房柜台上掉下一加仑牛奶)。这类事件具有裂缝网络发育和流体运移的迹象，为盖层完整性的任何破坏提供了潜在的早期预警信号。此外，这些活动有时会引发更大的事件(例如最近在兰开夏郡发生的M2.3事件)。尽管如此规模的事件不太可能造成重大破坏，但它们是当地居民关切的一个来源。布里斯托尔大学在过去10年里一直在这一领域进行研究，并在技术上走在了前列，因为行业规范是简单地定位事件。我们已经开发了一套软件，可以描述震源的特征，监控裂缝网络的发展，并有可能半实时地跟踪流体在地下的运移。布里斯托尔大学微震活动项目(BUPS)是由8家石油和天然气公司发起的联合行业项目(JIP)。进入第三阶段，重点已从技术开发转向回答运营商在非常规资源业务中面临的关键问题。拟议的催化剂供资将扩大该项目的范围，以包括环境影响监测。稀疏地震台网可用于监测页岩气地区的诱发地震活动。在目前的红绿灯系统下，运营决策将基于0.0-0.5级的事件做出。因此，需要准确和独立地估计诱发事件的大小。对于如此低震级的地震来说，要强劲地做到这一点是一项具有挑战性的任务，而目前英国的地震目录只完成到2.0级。因此，如果我们要明确地确定在刺激活动期间和之后检测到的任何事件的原因，就需要对地震活动进行完整的、低至这些低震级的基线调查。我们将在英国目前天然气勘探的地区部署一个稀疏的地震仪网络(见支持函)。这样的网络提供了对地震强度的独立估计，这是监测诱发地震活动的红绿灯所需的信息。为了监管目的和公众信心，重要的是这样一个地震网络由独立于石油和天然气运营商的机构建立和运营。为此，我们将制定一套页岩气增产环境影响监测的最佳实践指南。

项目成果

Microseismic Magnitudes: Challenges in Determining the Correct Moment and Operating Regulatory Frameworks

微震震级：确定正确时刻和操作监管框架的挑战

• DOI: 10.3997/2214-4609.201901238
• 发表时间: 2019
• 作者: Butcher A

Cracks, Fractures and Flow in Shales - Insights from Microseismicity

页岩中的裂缝、断裂和流动——微震活动的见解

• DOI: 10.3997/2214-4609.201600429
• 发表时间: 2016
• 作者: Kendall J

Seismic characterization of fracture compliance in the field using P - and S -wave sources

使用纵波和横波源现场地震表征裂缝顺应性

• DOI: 10.1093/gji/ggv395
• 发表时间: 2015
• 期刊: Geophysical Journal International
• 影响因子: 2.8
• 作者: Foord G

Subsurface fluid injection and induced seismicity in southeast Saskatchewan

萨斯喀彻温省东南部的地下流体注入和诱发地震活动

• DOI: 10.1016/j.ijggc.2016.04.007
• 发表时间: 2016
• 期刊: International Journal of Greenhouse Gas Control
• 影响因子: 3.9
• 作者: Verdon J

How big is a small earthquake? Challenges in determining microseismic magnitudes

• DOI: 10.3997/1365-2397.n0015
• 发表时间: 2019-02
• 期刊: First Break
• 作者: Jeffrey M. Kendall;A. Butcher;A. Stork;J. Verdon;Richard Luckett;B. Baptie