1. Sandy Chen*, L.R.Lines, J. Embleton, P.F. Daley, and L.F.Mayo
Cold production footprints of heavy oil on time-lapse seismology: Lloydminster field, Alberta
Sandy Chen*, L.R.Lines, J. Embleton,
P.F. Daley, and L.F.Mayo

2. Outline Mechanism of heavy oil cold production
Cold production geological models
Geophysical response of a cold production reservoir
Time-lapse seismic modeling of cold production drainage footprints

3. Mechanics of heavy oil cold production
- Non-thermal process
- Oil and sand produced simultaneously

4. Production rates with and without sands
With sand
Without sand
Wormhole network growth
Foamy oil drive
(Sawatzky, 2002)

5. Wormhole network Wormhole growth pattern Depth about 500 – 700m
(Miller et al., 2001)
Courtesy of KUDU Oil Well Pumps

6. Wormhole characteristics
10cm
“wormhole” created in reservoir lab simulation (Tremblay et al. ARC,1998 SPE/DOE symposium & EAGE Symp., 1999)

7. Foamy oil characteristics
Single propagating wormhole in a sandstone (Dusseault,1994)
Bubble
wormhole pipe
Foamy oil mechanism (D. Greenidge, Imperial Oil Resources)

8. Amplitude anomalies in drainage region
oil 9m3/d
cum oil 9E6m3
cum gas 2E6m3
oil 9m3/d
cum oil 12E6m3
cum gas 1E6m3
oil 10m3/d
cum oil 14E6m3
cum gas 1E6m3
400m
oil 7m3/d
cum oil 23E6m3
cum gas 2E6m3
oil 8m3/d
cum oil 14E6m3
cum gas 2E6m3
oil 5m3/d
cum oil 8E6m3
cum gas 2E6m3
oil 10m3/d
cum oil 24E6m3
cum gas 2E6m3
3D Seismic Amplitude Map in Lloydminster Filed after 9 years of production (Mayo,1996)

9. It is useful for engineers and geologists to know the size and distribution of drainage regions
Drainage footprint scenario for the cold production wells in a small southwest Saskatchewan heavy oil pool (Sawatzky, 2002)

10. Simplified drainage model (vertical wellbore)
Post-production reservoir state
Oil, water & foamy oil
initial reservoir state
Oil & water
wormholes
3D map view
borehole
Undisturbed region
Drainage region
Net Pay zone
2D cross-section

11. Pre-production reservoir model
Top McLaren
Bottom McLaren
Top Mannville
=2.26g/cm3, Vp=2496m/s
=2.37g/cm3, Vp=3227m/s
=2.16g/cm3, Vp=2795m/s Production Fm
=2.40g/cm3, Vp=3261m/s
2D synthetic seismogram of wormholes
Well log in Lloydminster Field

12. Most likely net pay zones
Gamma
Porosity
Resistivity
Two main net pays (red) in Mclaren reservoir sand. Upper sand, 5m net pay, lower sand 3m.

13. Post-production model with drainage region
Top McLaren
Bottom McLaren
=2.26g/cm3, Vp=2496m/s
=2.37g/cm3, Vp=3227m/s
=2.16g/cm3, Vp=2795m/s Production Fm
=2.40g/cm3, Vp=3261m/s
Top Mannville
Drainage region with Vp=????, =????
Well ?
Drainage regions 5m and 3m thick, and 200m and 300m long

14. Before production: oil & water
Recall that fluids state changes during production:
Before production: oil & water
After the start of production:
Foamy oil with gas bubbles, oil & water

15. Assumptions of mixed fluid states
Application of average fluid mixture states between the harmonic fluid state and the ‘Patchy’ weighted fluid (Reuss average & Voigt model )
Harmonic, Reuss average, lower bound
Patchy, Voigt average, upper bound
Here, Kg, Ko, Kw are derived from the methods demonstrated by Batzle and Wang (1992)

16. Applications of Gassmann’s Equation
Ks=36Gpa
The shear modulus is derived using dipole logs from Pikes Peak Area

17. In-situ reservoir parameters after 3-years of production
(Courtesy of Alberta Research Council)
(assuming no change in porosity and water saturation)

18. Physical properties of the drainage area

19. Post-production model with drainage region
Top McLaren
Bottom McLaren
=2.26g/cm3, Vp=2496m/s
=2.37g/cm3, Vp=3227m/s
=2.16g/cm3, Vp=2795m/s Production Fm
=2.40g/cm3, Vp=3261m/s
Top Mannville
Vp=2570m/s, =2.13g/cm3
Well

20. without drainage
with drainage
difference
Zero-offset seismic sections frequency bandwidth 200Hz (reverse display)

21. Impact of frequency on vertical resolution of
seismic images of the drainage areas

22. Conclusions
The presence of foamy oil is the key factor, resulting in amplitude anomalies. Time-lapse seismology can be a very useful tool for detecting cold production drainage patterns
The limitation of seismic frequency determines the images of the drainage footprints

23. Future Work - Wormholes
Wormhole effects on reservoir rock, especially when large amounts of sands are produced.
S-wave may be sensitive to the presence of wormholes

24. Acknowledgements COURSE Project CREWES Alberta Research Council
Dr. Ron Sawatzky

25. Backup slides

26. P-wave & S-wave Velocities v.s. Gas Saturation
P=3Mpa
P=3Mpa
Sg=0.1

28. Amplitude changes relative to bed thickness
fdom200Hz, 13m
fdom100Hz, 26m
Amp decrease
(Widess,1973)