American Oil and Gas Reporter - October 2016 - 65

in from the north and pushing the salt
out to create space. There was a
considerable clastic sediment input into
the Stampede basin during the lower and
middle Miocene period. The depositional
environment for these sands changed
from an unconfined channel setting in
Sh20s to an increasingly confined channel
setting in Gff10s as the basin itself became
more confined with developing salt highs
on the flanks.
Seismic data were used to determine
the lateral extent of the reservoir intervals
and their axial, off-axial, and marginal
settings. However, the data did not have
high enough resolution to determine the
details of the facies distribution in the
reservoir. To compensate, core data from
the reservoir intervals and logs along
with outcrop analogs from similar
deepwater depositional settings were used
to determine facies geometries and
distribution.
Figure 6 illustrates the multipoint
statistics (MPS) facies population approach
applied for each reservoir zone to build
the geological model. The Gff40s zone
is shown here, with the depositional environment scheme, facies elements, and
their proportion used for object definition,
training image and the final facies model.
An object was defined with depositional
facies elements (e.g., channel axis, median
lobes, etc.), and a training image was
constructed using that object. The training
image was used to control the facies
population in the 3-D geologic model.
Porosity was calculated from logs and
calibrated by core data, and permeability
was calculated using porosity/permeability
transformation functions derived from
core data. Facies population controlled
porosity and permeability distribution in
the geologic model.

in a multidisciplinary tool, Geo2Flow, to
identify reservoir compartments and free
water levels (FWLs).
FWL estimation uses J-functions that
couple porosity, permeability and saturations. Each well was fit separately to
core-derived J-curves to come up with
an FWL. Similar FWLs then were noted
between the wells to determine possible
compartments. The work suggested five
compartments as a best estimate case in
the Gff40s main reservoir.

Figure 7 illustrates the outcome of
the integration effort at the Stampede
Field. It displays the updated depth structure map of the Gff40s reservoir with
five compartments (identified by pink
dashed lines) and their estimated OWC
depths (blue dashed lines). Compartment
C1 is an aquifer.
As part of the integration effort, geochemical analysis of fluids in the wells
was incorporated to help better understand
compartmentalization. Alkyl-benzene

Reservoir Compartmentalization
In addition to none of the Stampede
exploration or appraisal wells penetrating
OWC in any of the three reservoirs, a
lack of pressure data from the "wet"
zones in these intervals made estimating
OWC more difficult. To compensate, we
used log and core-based saturation data
and modular dynamics tester pressures
OCTOBER 2016 65
American Oil and Gas Reporter - October 2016

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