Seismic Inversion
Roxar’s seismic inversion solution allows geoscientists to use seismic
data to create a rock property model quickly. Moreover, it provides
an accurate result with the implementation of highly efficient
geostatistical algorithms: fine scale information from well logs is
combined with the band-limited information from the seismic data
to provide an inversion where the output elastic parameters have
realistic behaviour.
IN SUMMARY
• Puts the power of seismic inversion in the hands of the
geomodeler.
RMS combines well data & seismic data to invert for elastic parameters.
• Provides elastic parameters to help constrain petrophysical
properties of the reservoir.
Incorporation of Seismic Data
• Facies probability cubes provide risk management support
for estimating reservoir quality.
Seismic inversion is a sophisticated process of inverting the seismic
data into elastic properties of the reservoir. This is made simple in
RMS and can retrieve the output parameters through fast
computation. Seismic data with various reflection angles can be
used to improve the inversion result as it utilises the fact that the
reflection strength from a subsurface interface depends on the
material properties of the geologic event.
Fast and Highly Automated Seismic Inversion
Optional automatic wavelet estimation and automatic time to depth
conversion provides an inversion tool accessible to the geologist. The
computed elastic parameters can be used to condition facies and
petrophysical models, or for visual inspection and data analysis. The
new facies probability parameter directly provides information
equivalent to many stochastic inversions. The facies probability
parameter provides an excellent QC tool, and can assist the
geomodeller to guide facies simulations in RMS’ rich facies modelling
toolbox.
Facies probaility volumes delineate channel structures in the subsurface.
Seismic Inversion
Maximum Output from Minimum Input
A minimum amount of input data and parameters are needed to do
inversion in RMS. RMS requires a grid volume of the region where the
inversion will be computed. The optimal input data is AVA stacks,
that is, stacks with common angle gathers. Facies logs are not
necessary unless inversion is done for facies probabilities. Minimum
well data requirement is a single vertical well with Vp, Vs , ρ and
two-way travel time.
The output parameters include Vp, Vs, Density, P-Impedance (AI),
S-Impedance (SI), Vp/Vs, Poisson Ratio, Lamé Lambda, Lamé Mu,
Original Seismic, Synthetic Seismic and Residuals. If facies log exists
in the blocked wells, then a facies probability parameter can be
created. It is also possible to output the estimated wavelets and
inversion time grid. The output can be quality checked by comparing
the original seismic data with the synthetic seismic or check the
residual generated using these two.
Facies probability statistics help risk reservoir management decisions.
Using Checkshot Surveys
The ability to tie wells to your seismic data via Checkshot surveys
plays an important role in improving the accuracy of your
interpretation, in addition to facilitating velocity analysis. RMS has a
provision for importing this data easily by way of time-depth tables
consisting of a standard two column ASCII file. These tables reside in
the individual wells folders, however one table can be used (linked)
to any number of wells which is useful if you have limited checkshot
data. Finally, it is fast and simple to create TWT logs from the time
depth data which is then required for input to the Seismic Inversion.
Roxar 2014
To learn more please visit www.roxarsoftware.com or email
us on [email protected].
ROXAR AS, GAMLE FORUSVEI 17, PO BOX 112, 4065 STAVANGER, NORWAY TELEPHONE +47 51 81 8800 FAX +47 51 81 8801 WWW.ROXAR.COM