Transcript Time-lapse seismic response and reservoir PVT properties

Time-lapse Seismic and
AVO Modeling, White
Rose, Newfoundland
Ying Zou and Larry Bentley
Outline
• Introduction
• Theory and methodology
• Case study: White Rose Field
Three production scenarios
Zero offset synthetics
PP and PS AVO modeling
• Conclusions
• Future work directions
• Acknowledgement
Introduction
Production of
gas or oil
Changes:
Bulk modulus
Shear modulus
Bulk density
Changes:
Saturation
Pressure
Temperature
Changes:
Seismic response
(e.g. PP, PS, AVO)
Theory and Methodology
(Bentley et al. CREWES Rpt., 1999)
Fluid properties + PVT data + Batzle & Wang(1992)
+ Vasquez & Beggs(1980)
rf and Kf
Kuold, muold and ruold
Velocity + density logs
 and Ks
Core
Ku
old
 Kd
old

(1  K d

Kf
old
Gassmann Eq.
/ K s )2
1   Kd


2
Ks
Ks
old
old
Theory and Methodology
Production
new
d
 Kd
new
u
 mu
K
m
Ku
new
 Kd
rfnew, Kfnew
New Saturation
Pressure
Temperature
new

(1  K d

Kf
new
old
Kunew , munew
 dK d
old
 dm u
new
/ K s )2
1   Kd


Ks
K s2
new
Theory and methodology
FluidSeis---A Matlab fluid substitution Program
Individual
fluid property,
Saturation & PVT
Fluid, rock property,
Saturation & PVT,
velocity & density logs
Above properties
for both pre and
post production
FluidSeis.m
FluidSeis.m
FluidSeis.m
rf , Kf
rf, Kf, Kd , Ku , ru
Above values &
their changes
Case study: White Rose field--
Well Location
White Rose field--Well logs
Case study: White Rose field-Three drive mechanisms:
From sea bottom
Original reservoir
Gas
2758 m
Oil
2851 m
In oil leg:
Sg=0%
So=78%
Swc=22%
Water
P & T maintained
Case study: White Rose field-Gas Drive
From sea bottom
Gas
Gas
2758 m
Oil
2851 m
In oil leg:
Sg=48%
Sor=30%
Swc=22%
Water
Water
P & T maintained
Case study: White Rose field-Water Drive
From sea bottom
Gas
2758 m
Oil
2851 m
In oil leg:
Sg=0%
Sor=30%
Sw=70%
Water
P & T maintained
Case study: White Rose field-Gas and Water
From sea bottom
Gas
Gas
2758 m
Oil
2851 m
Water
Water
P & T maintained
Case study: White Rose field--Results
Original
Mean value
Oil Leg
Ku
Vp
Vs
ru
GPa Kg/m2 m/s
m/s
20.4 2376. 4102. 2449.
Water drive
% change
Gas drive
% change
(Vp/Vs)
1.67
AIP
Kg/sm2
9756240
4.4
1.0
0.6
-0.5
1.1
1.6
-2.3
-1.9
0.4
0.9
-0.6
-1.5
Reflection Coefficient
Rcoeff
Original
Gas drive
Change (%)
Water drive
Change (%)
GOC
0.038
0.0311
-18.16
0.0447
17.63
OWC
0.0466
0.0550
15.27
0.0379
-18.67
P-P
Synthetic Zero Offset Traces
Water
Gas
L-08 VSP
drive
drive Original
Corridor Stack
Case study: White Rose field--PP wave AVO modeling
Gas-Water
Water
Gas
Original
NMO Corrected
trace gather
Stacked
trace
Original
Gas
Gas-Original
Original
Water
Water-Original
Original
Gas+
Water
Gas+Water
-Original
Case study: White Rose field--PS wave AVO modeling: pre-production
Original
Gas
Gas-Original
Original
Water
Water-Original
Summary
•
•
•
•
Velocity changes less than 1%
Density changes 1-2%
P-P Reflection coefficient changes 15-20%
P-P and P-S offset dependent changes are
sensitive to fluid substitution
• P-P and P-S AVO are more diagnostic of
fluid changes than stacked traces
Conclusions
• White Rose is a good candidate for
time-lapse reservoir monitoring
• Multi-component recording of P-S
converted waves appears to be a
useful reservoir monitoring tool
Future Work
• Add noise to synthetic traces
• AVO attribute analysis
• Exploring additional by-passed oil and
pressure maintenance scenarios
• True amplitude of seismic processing
Acknowledgements
• CREWES sponsors
• Husky Oil
Larry Mewhort Jill McLean
• Hampson-Russell
Qing Li