Reservoir characterization and modeling of lateral heterogeneity using multivariate analysis
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Description
Reservoir characterization deals with the description of the reservoir in detail for
rock and fluid properties within a zone of interest. The scope of this study is to
model lateral continuity of lithofacies and characterize reservoir rock properties
using geostatistical approach on multiple data sets obtained from a structural
depression in the bight of Bohai basin, China. Analytical methods used include
basic log analysis with normalization. Alternating deflections observed on
spontaneous potential (SP) log and resistivity log served as the basis for
delineating reservoir sand units and later tied to seismic data. Computation of
variogram was done on the generated petrophysical logs prior to adopting
suitable simulation algorithms for the data types. Sequential indicator simulation
(SIS) was used for facies modeling while sequential gaussian simulation (SGS)
was adopted for the continuous logs. The geomodel built with faults and
stratigraphical attitude gave unique result for the depositional environment
studied. Heterogeneity was observed within the zone both in the faulted and
unfaulted area. Reservoir rock properties observed follows the interfingering
pattern of rock units and is either truncated by structural discontinuities or
naturally pinches out. Petrophysical property models successfully accounted for
lithofacies distribution. Porosity volume computed against SP volume resulted in
Net to gross volume while Impedance volume results gave credibility to the
earlier defined locations of lithofacies (sand and shale) characterized by porosity
and permeability. Use of multiple variables in modeling lithofacies and
characterizing reservoir units for rock properties has been revisited with success
using hydrocarbon exploration data. An integrated approach to subsurface
lithological units and hydrocarbon potential assessment has been given priority
using stochastic means of laterally populating rock column with properties. This
method finds application in production assessment and predicting rock properties
with scale disparity during hydrocarbon exploration.
Keywords
QC Physics, QE Geology, TP Chemical technology