Microseismic monitoring became a broadly used tool for oil and gas unconventional and also conventional production. Its use ranges from mapping of hydraulic fractures, through compaction, cap rock integrity and faulting control in offshore reservoirs to control of seismic hazards related to the induced seismicity. This course provides an insight into the most common methodologies of microseismic monitoring discussing their advantages and limits of their applications. Participants will be able to set the right expectations, select the appropriate monitoring methodology and mainly interpret the data in a meaningful way.
Course Structure: 4 modules of max. 4 hours each, delivered over 4 days Each day will consist of 1 module which will be no more than 4 hours in length with ample time for delegates to break for refreshments.
Course Level: Skill Instructor: Leo Eisner
Designed for you, if you are...
A professional with a geoscience background
No specific prior knowledge is required, although a familiarity with geophysical terminology, hydraulic fracturing and/or earthquake seismology is useful.
How we build your confidence
Practical examples of data and computer simulations
Theoretical concepts are explained and illustrated on case studies
You will go through several exercises and test your ability to design monitoring and interpret the data
By the end of the course you will feel confident in your understanding of how to:
Decide on the type of monitoring array that will meet your goals
Design an array for passive seismic (surface or downhole) monitoring to meet your targets
Determine uncertainties of locations for microseismic events in microseismic monitoring arrays
Orient downhole geophones from a perforation or calibration shot
Quality check locations of microseismic events: estimate approximate distance and depth of a recorded microseismic event on a downhole array
Build a velocity model (P- and S-wave) from a sonic log or check shot measurement suitable for microseismic monitoring
Calibrate a velocity model for both surface and downhole arrays
Estimate the source mechanism from surface microseismic monitoring
Manage and mitigate hazards resulting from induced seismicity
Estimate the stimulated reservoir volume
Effectively use the information provided by microseismicity
Understand how the stress is constrained by microseismic events
Introduction - Definition of microseismicity, induced / triggered seismicity - A brief review of microseismicity outside the oil industry: water reservoirs, mining and geothermal - Induced seismicity by reservoir production - Historical review of microseismicity during reservoir production - Historical review of microseismicity by hydraulic fracturing (M-site, Cotton Valley, Barnett, etc.) - Principles of hydraulic fracturing and geomechanics
Earthquakes - Instrumentation for passive seismic from accelerometers to DAS - Frequency content of the microseismic data - Earthquake location techniques - Relative locations - Microseismic location techniques and exercises
Downhole location technique - Single well monitoring technique - P-wave and S-wave polarisation - P-wave only location from downhole arrays - Picking strategies for microseismic data - Optimal design of downhole monitoring array with exercise - Orientation of downhole geophones - Velocity model calibration - Inclined / dual and multi-well monitoring techniques
Surface monitoring technique - Vertical component only, uncertainty associated from P-wave locations: depth vs. origin time - Detection uncertainty and signal-to-noise ratio - Frequency content, attenuation and detection - Design of surface monitoring array - Calibration shots / velocity model building: isotropic vs. anisotropic velocity - Relative locations - Downhole and surface location case study - Near surface amplification
Source mechanisms - Concept of source mechanism, definition of dip, strike and rake for shear source - Description of shear, tensile, volumetric, CLVD source through moment tensor - Inversion for source mechanisms from single monitoring borehole / multiple monitoring boreholes / surface P-only data - Observed source mechanisms of microseismic events - Stress constrained by source mechanisms
Source characterisation - Magnitude: local, moment and other types - Magnitude and energy: do not use TNT equivalents - B-value and magnitude of completeness - Stress drop, source dimensions
Anisotropy - Introduction to anisotropy - Effect of anisotropic media on S-waves: shear wave splitting - Shear wave splitting observed in microseismic data - Inversion of anisotropic media from P and S-waves using microseismic events - P-wave anisotropy on surface monitoring data - Time-lapse changes in anisotropy
Reservoir simulations - Current use of microseismicity in the oil industry - Diffusion model for pressure triggering of microseismic events - Discrete fracture networks constrained by microseismicity - Reservoir simulations and history matching
Seismicity in the vicinity of oil or gas reservoirs - Theory and history of induced felt seismicity - Seismic moment and total injected volume - Blackpool case study as an example of induced seismicity - DFW seismicity case study - Social issues related to hydraulic fracturing
Case studies and conclusions - Recent important case studies: locations and source mechanisms - Relationship between microseismicity and hydraulic fracturing - Summary of the class - The most important things to remember about microseismicity