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The key behind building a successful and reliable reservoir model that
could be useful for reservoir simulation or planning purposes is to be able
to constrain the well data by one or multiple seismic attributes.
Without the use of seismic attributes, the property models will suffer from
a wide range of problems in the interwell region
thus becoming unreliable as commonly seen when used in a reservoir
simulator where past performances are not matched. Prism Seismic developed in CRYSTAL the necessary seismic tools to reduce uncertainties in property
modeling.
Prism Seismic uses many algorithms to generate petrophysical properties. The algorithms implemented in CRYSTAL include geostatistical
methods, a clould transform, and a neural network.
The geostatistical
methods include Kriging and Sequential Gaussian
Simulation (SGS). The implementation of these methods in CRYSTAL
use proprietary Prism Seismic technologies not found in other E&P
software that rely on GSLIB. The differences between Prism Seismic
implementations of these algorithms with the rest of E&P software can
be seen through the speed and accuracy of the calculations.
Another very powerful way to generate geologic models is to use the cloud
transform. This algorithm is able to reproduce accurately the complex
relationships that may exist between two rock properties such as porosity
and permeability. The standard approach used throughout the industry is to
apply a regression to the porosity and thus generate the permeability. When
using the cloud transform, the permeability minimum and maximum values are
not eliminated and the entire complex relationship is accounted for. Such a
robust approach could be used on many reservoir properties including generating
porosity from impedance.
Since Kriging
and SGS provides the ability to constrain the geological models to only one
seismic attribute, CRYSTAL provides a neural
network able to build models constrained to multiple seismic attributes. Prism Seismic consulting experience throughout the world has shown that using multiple seismic attributes provides better
results.
All the CRYSTAL property modeling
algorithms can be applied to both geocellular
grids available in
time and depth domains.
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