sandy chen*, l.r.lines, j. embleton, p.f. daley, and l.f.mayo
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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 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 Mechanics of heavy oil cold production
- Non-thermal process - Oil and sand produced simultaneously
Production rates with and without sands
With sand Without sand Wormhole network growth Foamy oil drive
(Sawatzky, 2002) Wormhole network Wormhole growth pattern Depth
about 500 700m
(Miller et al., 2001) Courtesy of KUDU Oil Well Pumps Wormhole
characteristics
10cm wormhole created in reservoir lab simulation (Tremblay et al.
ARC,1998 SPE/DOE symposium & EAGE Symp., 1999) Foamy oil
characteristics
Single propagating wormhole in a sandstone (Dusseault,1994) Bubble
wormhole pipe Foamy oil mechanism (D. Greenidge, Imperial Oil
Resources) 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) 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)
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
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/sProduction Fm
=2.40g/cm3, Vp=3261m/s 2D synthetic seismogram of wormholes Well
log in Lloydminster Field 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.
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/sProduction Fm =2.40g/cm3,
Vp=3261m/s Top Mannville Drainage regionwith Vp=????, =???? Well ?
Drainage regions 5m and 3m thick, and 200m and 300m long 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 Assumptions of mixed fluid
states
Application of average fluid mixture states between the harmonic
fluid state and the Patchy weightedfluid (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) Applications of Gassmanns
Equation
Ks=36Gpa The shear modulus is derived using dipole logs from Pikes
Peak Area In-situ reservoir parameters after 3-years of
production
(Courtesy of Alberta Research Council) (assuming no change in
porosity and water saturation) Physical properties of the drainage
area 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/sProduction Fm =2.40g/cm3,
Vp=3261m/s Top Mannville Vp=2570m/s, =2.13g/cm3 Well without
drainage with drainage difference Zero-offset seismic
sectionsfrequency bandwidth 200Hz (reverse display) Impact of
frequency on vertical resolution of
seismic images of the drainage areas 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 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 Acknowledgements COURSE Project CREWES Alberta Research
Council
Dr. Ron Sawatzky Backup slides P-wave & S-wave Velocities v.s.
Gas Saturation
P=3Mpa P=3Mpa Sg=0.1 Amplitude changes relative to bed
thickness
fdom200Hz, 13m fdom100Hz, 26m Amp decrease (Widess,1973)
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