Monitoring: Passive methods (induced seismicity)

Description

Passive monitoring: In introduction, we will cover the various settings in which passive seismic monitoring of reservoir are employed today and the usefulness of such monitoring. We will then dedicate some time discussing the characteristics of the different seismic equipment and the design of an appropriate strategy for monitoring a reservoir (borehole vs surface sensor, network vs array, …). In a third chapter we will cover modern techniques for detecting and locating with high precision small amplitude signal such as micro-seismic events. The fourth chapter will investigate the methods that can be used for inferring the stress state and the pore pressure at depth from the analysis of these small earthquakes. Namely, we will review the methods for focal mechanism computation and stress tensor inversion techniques applied to these data. In a final chapter we will see how we can extract information about the reservoir from the analysis of the background seismic signal. Typically, we will look at the spectral shape of this background signal and derived velocities and velocity variations from the record of the background seismic noise. Numerous case studies will be studied during the course and we will dedicate a significant part of the lectures to the applications of the theoretical concepts with computer exercises on real dataset.

Compétences visées

This teaching can be linked to the skills of the geophysical engineer as defined in the training matrix:

• The ability to mobilise the resources of the major scientific fields of geophysics and geology, applied to reservoirs, hydrology and soil mechanics. On completion of this course, you will be able to integrate knowledge of mechanics and seismology, to take part in signal processing. 

• Expertise in engineering tools: identification, modelling and resolution of complex geophysical problems using a scientific and global approach, use of numerical approaches and IT tools, analysis and modelling of hydro-thermal-mechanical couplings in the subsurface, risk and crisis management, collaborative and remote working. The expected development of this skill will be to be able to analyse the microseismicity of a reservoir, from the choice of relevant equipment to the analysis of the data.

• The ability to design, implement, test and validate innovative solutions, methods, products, systems and services to characterise, image and monitor the subsurface in response to a problem. At the end of this course you will be able to use modern seismological tools to monitor seismicity.
• The ability to take account of the issues and needs of society and to disseminate the principles and contributions of the scientific approach. This course will help you to understand how the monitoring of underground reservoirs can contribute to the energy transition, and you will be able to communicate the associated seismic risks accurately.

Discipline(s)

• Terre solide : géodynamique des enveloppes supérieure, paléobiosphère
• Enveloppes fluides du système Terre et autres planètes
• Génie informatique, automatique et traitement du signal