Geology Reference
In-Depth Information
Net pay thickness
Apparent thickness
Figure 10.20
Model data template generated for a turbidite reservoir. Note that the net pay lines are effectively averages as there is
considerable overlap. Blue wells were blind tests whilst the red well was the basis for the pseudo-well data in the model. After Fervari and
Luoni (
2006
).
surveys effectively highlight where production effects
have occurred (
Fig. 10.23
). Amplitude maps can give
a dramatic indication of large scale changes over the
field area (
Fig. 10.24
). Detailed interpretation of the
time-lapse signal in terms of fluid flow (e.g. identify-
ing barriers and estimating sweep efficiency in reser-
voir compartments) and the identification of
remaining reserves requires careful reference to the
baseline reservoir description and geological model.
The results can be used to optimise infill drilling and
manage injection/production strategies. The reader
is referred to excellent summaries of time-lapse tech-
nology given by Jack (
1997
), Calvert (
2005
)and
Johnston (
2013
).
Figure 10.25
shows a view of the time-lapse pro-
cess in which a seismic floodmap based on time-lapse
seismic interpretation is used to update the field
simulation. In some instances, the level of integration
is even greater than that implied in the figure, with
the reservoir simulation being fully integrated with
the seismic observations via a
dynamic and static reservoir models have a high
degree of consistency. Many modern time-lapse pro-
jects seek to
(Gutteridge et al.,
1994
)
by comparing seismic models generated from the
simulation with the acquired data. In this way history
matching of the simulation can be validated or
adjusted. rock physics modelling (
Chapters 5
and
8
)
provides the basis for interdisciplinary consistency
(e.g. Gawith and Gutteridge,
2007
).
Time-lapse seismic is a relatively new technology
founded largely through advances in the understand-
ing of reservoir rock physics in the late 1980s and
early 1990s (e.g. Wang,
1997a
). Prior to this time,
time-lapse effects had generally been described from
fields on land with fairly large changes in compress-
ibility, a classic example being the fire flood project
described by Greaves and Fulp (
1987
). It was uncer-
tain whether or not there was sufficient signal or
detection capability to make it a key technology for
offshore developments particularly in conventional
oil reservoirs. From tentative beginnings, various
studies, largely on North Sea fields, essentially proved
technical viability. Subsequently, experience shows
that the net value gain associated with the use of
'
close-the-loop
'
'
(Riddiford and Goupillot,
1993
). A good example of
this level of discipline integration has been described
from Draugen field (Guderian et al.,
2003
), where
'
shared earth model
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