J. Grotsch et C. Mercadier, Integrated 3-D reservoir modeling based on 3-D seismic: The tertiary Malampaya and Camago buildups, offshore Palawan, Philippines, AAPG BULL, 83(11), 1999, pp. 1703-1728
Citations number
30
Categorie Soggetti
Earth Sciences
Journal title
AAPG BULLETIN-AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS
Three-dimensional (3-D) seismic interpretation and drilling results indicat
e complex sedimentary geometries of the Malampaya and Camago buildups (offs
hore Palawan, Philippines) with localized progradation due to unidirectiona
l offbank transport alternating with vertical aggradation. Successive reduc
tion of size during buildup growth and backstepping of the protected landwa
rd margin in response to transgression ultimately appear to have triggered
the demise of carbonate production and platform drowning. The shallow-water
platform top sediments repeatedly show signs of subaerial exposure before
reflooding,
A modeling functionality was developed to allow development of multiple-sce
nario 3-D reservoir models in an exploration or appraisal stage. The model
enables merging of seismic-scale observations based on 3-D volume and horiz
on analyses with subseismic scale information from well data; however, inhe
rent noise within the seismic data introduced by the complex buildup morpho
logy has resulted in inconsistent attribute distribution and fault dimming,
These difficulties are compounded by erratic velocity distribution within
the limestone, nonhyperbolic move out, and a narrow relatively low-frequenc
y spectrum, all of which prevent the use of the 3-D seismic volume as hard
data but rather allow its use as a soft constraint for guiding the geologic
al interpretation and ultimately the modeling process. Seismic data quality
in such complex morphologic settings and scarcity of well data hamper grea
tly the use of geostatistically driven modeling approaches; therefore, a ne
w functionality was developed within Shell's proprietary integrated 3-D mod
eling suite (GEOCAP), which allows deterministic model reservoirs using sei
smic horizon and volume interpretation, sequence- and cyclo-stratigraphic a
rchitecture, and the concept of reservoir rock type.
Seismic velocity in clean carbonate formations is predominantly a function
of porosity distribution. To assess time-to-depth conversion uncertainty, t
he reservoir rock type based models were first produced in the time domain.
Only after differential 3-D depth conversion of these models could the sce
narios be reconstructed in the depth domain. The depth models subsequently
were used to derive permeability and saturation 3-D distortions, and thus h
ydrocarbon volumes for each deterministic scenario. The models were then us
ed for simulation purposes.