Abstract: From Rocks
to Models: Three-Dimensional Visualization as a Tool to Integrate Sedimentology
and Sequence Stratigraphy into Reservoir Models
TINKER, SCOTT W.
If every subsurface reservoir
had an exact analog exposed in a continuous outcrop, interpretation
of
subsurface frameworks would improve dramatically. Unfortunately, this is
not the case. Three-dimensional visualization technology provides a tool
that allows the interpreter to "visualize" the stratigraphic framework,
in much the same way one would look at an outcrop. Used in this fashion,
visualization becomes an interactive
interpretation
tool that relies on
the remarkable ability of the human mind to process and comprehend a color,
animated image. As such, visualization is a powerful component of reservoir
characterization.
The 3-D reservoir model, which
incorporates core, wireline log, seismic
, and production
data
within a
3-D stratigraphic framework, is an important product of the reservoir characterization
process. The model-building process is dynamic, with constant modification
made as a function of visualization, new
data
, and fresh ideas. One of
the risks of 3-D modeling is that the attractive visual result can mask
an erroneous stratigraphic
interpretation
and/or poor choice of
data
-distribution
methods. An erroneous 3-D model used as a reservoir development tool can
actually have a negative impact on production results. In contrast, an
accurate 3-D model provides a realistic matrix permeability
interpretation
,
and is a powerful reservoir management tool.
The stratigraphic/structural
framework plays an important role in 3-D reservoir modeling, because the
framework constrains the distribution of data
in 3-D space. A rigorous
sequence-stratigraphic
interpretation
provides the best framework for 3-D
data
distribution. Reservoir-scale
If every subsurface reservoir
had an exact analog exposed in a continuous outcrop, interpretation
of
subsurface frameworks would improve dramatically. Unfortunately, this is
not the case. Three-dimensional visualization technology provides a tool
that allows the interpreter to "visualize" the stratigraphic framework,
in much the same way one would look at an outcrop. Used in this fashion,
visualization becomes an interactive
interpretation
tool that relies on
the remarkable ability of the human mind to process and comprehend a color,
animated image. As such, visualization is a powerful component of reservoir
characterization.
The 3-D reservoir model, which
incorporates core, wireline log, seismic
, and production
data
within a
3-D stratigraphic framework, is an important product of the reservoir characterization
process. The model-building process is dynamic, with constant modification
made as a function of visualization, new
data
, and fresh ideas. One of
the risks of 3-D modeling is that the attractive visual result can mask
an erroneous stratigraphic
interpretation
and/or poor choice of
data
-distribution
methods. An erroneous 3-D model used as a reservoir development tool can
actually have a negative impact on production results. In contrast, an
accurate 3-D model provides a realistic matrix permeability
interpretation
,
and is a powerful reservoir management tool.
The stratigraphic/structural
framework plays an important role in 3-D reservoir modeling, because the
framework constrains the distribution of data
in 3-D space. A rigorous
sequence-stratigraphic
interpretation
provides the best framework for 3-D
data
distribution. Reservoir-scale sequence stratigraphic
interpretation
involves a systematic process of 1-D, 2-D, and 3-D
interpretation
of core,
wireline log,
seismic
, and production
data
. The result is a 3-D stratigraphic
framework
interpretation
that is consistent and repeatable. The stratigraphic
complexity, and therefore
interpretation
difficulty, increase as a function
of depositional topography and magnitude of eustatic sea level change (icehouse
vs. greenhouse). Although most reservoir-scale interpretations today are
called sequence stratigraphic, some do not honor depositional environment
and accommodation constraints. Examples of erroneous stratigraphic interpretations
include horizontal stratigraphy in an actual clinoform setting (e.g., shelf
margin), and clinoform stratigraphy in an actual horizontal setting (tidal
flat); toplap with an associated erosional sequence boundary in an actual
shelfward-thinning sigmoidal clinoform setting; and onlap onto an underlying
margin in an actual high-angle sigmoidal clinoform setting.
Examples from several depositional
settings will be used to illustrate the process of high-frequency sequence-stratigraphic
interpretation
and the 3-D geologic models that result, including "layer-cake"
stratigraphy in a tidal flat setting, low-angle sigmoidal clinoforms in
a ramp setting, high-angle sigmoidal clinoforms in a steep-rimmed margin
setting, and complex sigmoid-oblique clinoforms in a steepened-ramp setting.
AAPG Search and Discovery Article #90938©1997-1998 AAPG Distinguished Lecturers