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)