Geoscience Reference
In-Depth Information
Top Chalk (Danian D1)
Gas
GOC
5850
Oil
Danian D2)
5900
Water
5950
6000
Top Maastrichtian
6050
OWC
Volume Fraction
Fig. 3.47 RFT data for three wells for the Kraka field
(From Thomasen and Jacobsen 1994 ) (Redrawn from
Thomasen and Jacobsen 1994 ,
Fig. 3.48 Type log for the Kraka field illustrating the
variable oil saturations and the thick transition zone
(Redrawn from Thomasen and Jacobsen 1994 ,
1994, Society of Petro-
leum Engineers Inc., reproduced with permission of SPE.
Further reproduction prohibited without permission)
#
1994,
Society of Petroleum Engineers Inc., reproduced with
permission of SPE. Further reproduction prohibited with-
out permission)
#
The slope of the free-water level inferred from
this was found to be close to the RFT pressure
data model.
￿ An intra-reservoir seismic reflection
interpreted as the matrix oil-water contact
was mapped around the field and extrapolated
to its intersection with top reservoir, and was
again found to be in good agreement with the
saturation model.
￿ The orientation of the inferred hydrodynamic
gradient (towards the SE) was found to be in
agreement with regional gradients from inter-
field pressure variations.
This integrated interpretation had a significant
economic benefit in terms of the appropriate
placement of horizontal wells in the thicker part
of the accumulation, and in the estimation of
inter-well permeability in this fairly marginal
field development.
3.8
Summary
We have covered a range of issues related to
petrophysical property modelling of oil and gas
reservoirs. The theoretical principles that under-
lie the modelling “buttons” and workflows in
geological reservoir modelling packages have
been discussed along with many of the practical
issues that govern the choice of parameters.
To summarise this chapter, we offer a check
list of key questions to ask before proceeding
with your property modelling task:
1. Have you agreed with your colleagues across
disciplines (geoscience, petrophysics and res-
ervoir engineering):
￿ The key geological issues you need to
address - rock heterogeneity, sedimentary
barriers, faults, etc.
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