Post on 25-May-2020
The Domain - Seismic Mechanisms in the WCSB
Factors relevant to induced seismicity have been determined for the WCSB:
• Region (pre-existing faults)
• Hydraulic fracking
• Water disposal
• Pore overpressure
Risk and Hazard ManagementThe risk model is based on factors that are observable and can be monitored externally. This will allow continuous risk assessment and mitigation.
The model allows for future amendments to components while retaining the overall structure. It allows the introduction of new technologies for exploitation without major changes.
The model is objective and defines responsibilities for the licensee and the regulator
Components include:
• Data requirements (seismic catalogue and monitoring)
• Rate and magnitude models specific to geological regions
Public Data Sources
• Hydraulic fracturing records (>10,000 pdf files)
– MER – RGE – TWP – SEC – LSD
• Well locations ( >500,000 wells)
– UWI
• Earthquake data
– Latitude, longitude
Induced Seismic Activity in WCSB
Seismicity increase between April 2009 and December 2011 in the Horn River Basin
Activity is regionally confined and associated with deployment of new resource development technologies; horizontal drilling and multistage hydraulic fracturing
Induced Seismic Activity in WCSB
Fox Creek, Duvernay Zone, AER Subsurface Order No 2
BC Alberta
Total 31,609 587,243
Non Abandoned 24,445 501,897
Candidate HF 15,786
Candidate Disposal 3,840
Associated HF 50
Associated Disposal 52
Affected Producers(Alberta)
• Encana has four times the number of applications as the next licensee
• 20 out of 252 licensees (8%) account for 50% of applications
• Seismic and operations timing data are required
• 1 year embargo on other operational data
Managing Risk
Monitor the process to identify changes before they cause a problem or a shutdown. Data should be quantitative and timely.
The risk model is based on factors that are observable and can be monitored externally. This will allow continuous risk assessment and
mitigation.
Seismic Risk Assessment
1. Determine seismic catalogue and ongoing real time data collection and update process
• CASC catalogue(Atkinson, et al.)
• Small events (>1 ML) required in restriction zones
2. Rate of events
• Poisson arrival time with change point detection
3. Define restriction zones
4. Magnitude of events
• Truncated Pareto distribution
• Truncated exponential distribution
Arrival time of earthquakes follows a Poisson process
• random arrival times
Magnitude follows a Power Law
• word frequency, letter frequency, page views, size of forest fires, cities, Facebook likes
Probability Distributions
Seismic Event Rate Change Detection
• Time windows start when fracking commences for internal monitoring and continue with real time analysis
• Poisson arrival time change point detects rate changes within restriction zone
Ross, Gordon J., Journal of Statistical Software (2015), v 66, pp. 1-20
Seismic Event Magnitude Changes
• Changes in magnitude distributions after change points (Gutenberg-Richter relationship) 902 events
Seismic Risk Management
• Rate changes or fracking operations define data collection time periods
• Daily report based on magnitude distribution quantifies daily changes in seismic risk
Risk Management Process Flow Proactive
Incorporate broader play based risk factors (geologic insights* injection volume, pressure and rate).Update quarterly or yearly
Reactive
Change threshold to >2 ML,
*such as Schultz , et al. (2016)