HEAVY-OIL SEISMIC MONITORING at PIKES PEAK, SK I.A. Watson*, L.R. Lines and K.F. Brittle November 20, 2001

Combined two CREWES papers Combined two CREWES papers – “Heavy-oil time-lapse seismic monitoring at Pikes Peak, Saskatchewan” – “Heavy-oil reservoir characterization using elastic wave properties”

Outline Introduction Introduction Geology Geology Analysis 1: Section Differencing Analysis 1: Section Differencing Analysis 2: Isochron Ratio Analysis 2: Isochron Ratio Analysis 3: Vp/Vs Ratio Analysis 3: Vp/Vs Ratio Conclusions Conclusions

Pikes Peak Time-lapse Injected steam Injected steam – Reduces reservoir impedance – Causes increased compressional wave traveltime Two (time-lapse) seismic lines Two (time-lapse) seismic lines – 2-D lines in co-incident locations 1991 (swath) 1991 (swath) 2000 (multi-component) 2000 (multi-component)

Pikes Peak Heavy-oil field Heavy-oil field Operated by Husky Energy Operated by Husky Energy 40 km east of Lloydminster 40 km east of Lloydminster Over 40 million bbls produced Over 40 million bbls produced Steam injection operation Steam injection operation

DATA 200+ wells 200+ wells D swath D swath C-2D C-2D 2000 VSP 2000 VSP Pikes Peak Field Map

Data Comparison H1991 February sec Hz non-linear 3 vibrators over 20 m 4 sweeps/vp 10 m drag length 40 m source interval 20 m group interval 9 geophones over 20 m 30 CDP fold Bandwidth 14 – 110 Hz H2000 March sec Hz non-linear 2 vibrators over 20 m 4 sweeps/vp No drag 20 m source interval 20 m group interval 6 geophones over 10 m 66 CDP fold Bandwidth 14 – 150 Hz

Data Comparison

Pikes Peak Geology Waseca Trend in Pikes Peak Area Van Hulten, 1984

Pikes Peak Geology Incised valley Incised valley Estuarine -point bars Estuarine -point bars N-S N-S ~500 m depth ~500 m depth Salt dissolution structure Salt dissolution structure and stratigraphic trap and stratigraphic trap 80-90% oil saturation 80-90% oil saturation 5-30 m net pay 5-30 m net pay 32-36% porosity 32-36% porosity 1-10 darcies perm darcies perm. 12° API 12° API Van Hulten, 1984

Analysis 1: Section Differencing Time-lapse differences of Time-lapse differences of – Reflectivity – Acoustic Impedance (AI)

Calibration Required prior to differencing Required prior to differencing Hampson-Russell’s Pro4D Hampson-Russell’s Pro4D Adjustments for: Adjustments for: Time Time Amplitude Amplitude Phase Phase Time window above zone of interest Time window above zone of interest Trace-by-trace gave best results Trace-by-trace gave best results

Refectivity Differencing Applied a wavelet-shaping filter to H2000 Applied a wavelet-shaping filter to H2000 Differences seen below reservoir Differences seen below reservoir Increase in traveltime caused by presence of injected steam Increase in traveltime caused by presence of injected steam Does not allow signal to cancel Does not allow signal to cancel Other differences Other differences Noise Noise Acquisition parameters Acquisition parameters

H1991 Reflectivity Section NS

H2000 Reflectivity Section

Reflectivity Difference Section

Impedance Differencing Applied a band-pass filter, wavelet shaping and time and phase matching to H2000 Applied a band-pass filter, wavelet shaping and time and phase matching to H2000 Significant differences seen within reservoir zone – lower impedance Significant differences seen within reservoir zone – lower impedance Lower AI extends further than expected Lower AI extends further than expected Has the steam reached further? Has the steam reached further? Limited by 2-D section Limited by 2-D section

H1991 AI Section

H2000 AI Section

AI Difference Section

Analysis 2: Isochron Ratio Interpretation based Interpretation based – H1991 and H2000 – Waseca-Sparky interval

Isochron ratio Addition of steam Addition of steam – Vp decrease – Increase in 2000/1991 isochron ratio Position of steam zone predicted on line Position of steam zone predicted on line Seismic line Steam zone on line Steam zone radius Husky, 2000

D2-6 Waseca Core Analysis Temperature (°C) Velocity (m/s) Compressional Source: Core Laboratories

H1991 Reflectivity Section

H2000 Reflectivity Section

2000/1991 P-P Isochron Ratio (Waseca-Sparky)

Analysis 3: Vp/Vs Ratio Interpretation based Interpretation based – H2000 multi-component only – PP and PS sections – 2 intervals

Vp/Vs ratio Addition of steam Addition of steam – Vs decrease < Vp decrease –  Vp/Vs decrease = steamed zone Vp/Vs ratio derived from P-P and P-S interpretations Vp/Vs ratio derived from P-P and P-S interpretations Margrave et al., 1998

D2-6 Waseca Core Analysis Temperature (°C) Velocity (m/s) Shear Compressional Source: Core Laboratories

H2000 P-P (Vertical Component)

H2000 P-S (Radial Component)

Vp/Vs Isochron Ratio (Waseca-Sparky)

Vp/Vs Isochron Ratio (Mnvl to L.Mnvl)

Conclusions Anomalies are generally located where expected Anomalies are generally located where expected Inferred steam response on both the time- lapse and the Vp/Vs ratio plots Inferred steam response on both the time- lapse and the Vp/Vs ratio plots Difficult interpretation on converted wave data Difficult interpretation on converted wave data Potential lateral lithology changes identified Potential lateral lithology changes identified Minimize all variables external to the reservoir Minimize all variables external to the reservoir 3-D seismic data is recommended 3-D seismic data is recommended

Acknowledgements Husky Energy Husky Energy AOSTRA (COURSE) AOSTRA (COURSE) Jason Geosystems Jason Geosystems Hampson-Russell Hampson-Russell CREWES CREWES NSERC and Imperial Oil NSERC and Imperial Oil

PS synthetic: GMA

Acoustic Impedance ( AI ) AI obtained through inversion AI obtained through inversion Band limited result Band limited result Trace-based vs. model-based Trace-based vs. model-based Post-stack interpretation technique Post-stack interpretation technique McQuillin 1984

AI Inversion Reduces effect of wavelet sidelopes and tuning Reduces effect of wavelet sidelopes and tuning Interpret boundaries and evaluate internal properties Interpret boundaries and evaluate internal properties Allows direct comparison of time-lapse surveys Allows direct comparison of time-lapse surveys Inversion performed using Jason Geoscience Inversion performed using Jason Geoscience

Well Months before H91 Months before H00 3B D C B8-6n/a0 2B9-6n/a26 1D10-6n/a12 Injection Information

PS synthetic: matlab 0 300