Fracking and Earthquakes What s the Risk? Alastair Muir, President Muir&Associates Consulting

Transcription

1 Fracking and Earthquakes What s the Risk? Alastair Muir, President Muir&Associates Consulting

2 Who am I? Big data since 1979

3 Hydraulic Fracturing Induced Earthquakes

4 Earthquake Prediction Since my first attachment to seismology, I have had a horror of [earthquake] predictions and predictors. Journalists and the general public rush to any suggestions of earthquake prediction like hogs toward a full trough. - Charles Richter, 1977

5 This Project is: Determining the quantitative risk of inducing a >4 M L seismic event within 5 km of a well during hydraulic fracturing operations in the Western Canadian Sedimentary Basin.* Not about Subsurface water quality or climate change Water disposal wells Construction standards or ground motion Geological insights into locations of induced seismic events Cumulative earthquake risk Earthquake prediction *Not restricted to Duvernay

6 Managing Risk Monitor the process to identify changes before they cause a problem or a shutdown. Data should be quantitative and timely.

7 Induced Seismic Risk Management The 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

8 What data do you need? What data do you have?

9 Public Data Sources Hydraulic fracturing records (fracfocus.ca) >10,000 pdf files MER RGE TWP SEC LSD Well locations: ST37 (aer.ca) >500,000 wells) Universal Well Identifier Earthquakescanada.nrcan.gc.ca Latitude, longitude, magnitude >3-2.5 M L

10 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

11 Induced Seismic Activity in the 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

12 Induced Seismic Activity in WCSB BC Alberta Total 31, ,243 Non Abandoned 24, ,897 Candidate HF 15,786 Candidate Disposal 3,840 Associated HF 50 Associated Disposal 52

13 Seismic Risk Assessment The risk model is based on factors that are observable and can be monitored externally. This will allow continuous risk assessment and mitigation. 1. Determine seismic catalogue and ongoing real time data collection and update process CASC catalogue(atkinson, et al.) Small events (>1 M L ) 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

14 Modelling The sciences do not try to explain, they hardly even try to interpret, they mainly make models - John von Neumann, 1961

15 Probability Distributions Arrival time of earthquakes follows a Poisson process random arrival times Magnitude follows a Power Law word frequency, letter frequency, webpage views, size of forest fires, earthquakes, cities, number of Facebook likes

16 Seismic Event Rate Change 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

17 Seismic Event Magnitude Change Fracking operations define data collection time periods Pattern of seismic events allows for an estimate of the risk of >4M L events Public data is difficult to access, process and is too sparse Decreased risk

18 More Data Allows Better Assessment Much more data, timely, specific, annotated, combined with production data Proprietary, delayed Changes in frequencies of events after changes in well completion plan

19 Seismic Event Risk Changes Changes in magnitude distributions after change points Decreased risk

20 Implementing the solution

21 Risk Management Process Flow Proactive Incorporate broader play based risk factors (geologic insights* injection volume, pressure and rate). Update quarterly or yearly *such as Schultz, et al. (2016) Reactive Change threshold to >2 M L,

22 Reporting and Monitoring - Alberta

23 Reporting and Monitoring - BC

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25 Tools of the Trade