A Layerbased Velocity Model Is Built Within The Structural Model Using:
- Vertical and/or lateral gradient function
- Interpolation of velocities defined at the top and at the bottom of the layer
- DSI, krigging, collocated co-krigging methods with combination of velocity information such as well velocities, check shot velocities or other velocity functions
- User defined velocity function (V = V0 + k (Z1 + Z0), V = V0, and much more)
- Linear function of existing property
- Well markers
A given velocity model may be locally refined using stratigraphically constrained interpolation. For example, check-shot velocities may be co-kriged against a background of seismically-derived velocities within a stratigraphic framework. This method preserves local sedimentary dip and faulting.
Velocity conversion (RMS, interval and average) is available in time and depth domain. Data integration facilitates manipulating different kinds of data at the same time such as stacking, interval or average velocities and well velocities. Velocities can be stored in a 3D cube but also on any user-specified horizon and manipulated using script, interpolation or krigging methods.
To check velocity consistency, users can easily display vertical cross sections through the velocity cube with seismic horizons as overlay (co-rendering of velocity and amplitude on any arbitrary slicer, probes or sections). Arbitrary section can be displayed along the well path and velocity property can be painted.
For the purpose of uncertainty analysis interpretation, users may build several velocity models and use them to time-to-depth convert a structural model. The various depth models resulting from the different velocity cubes may then be used as inputs to the Rock Volume Uncertainty Assessment tool or Jacta, either as discrete scenarios or by specifying the "uncertainty envelop" extracted from the different depth models. The impact and relative importance of the different velocity models on the final reservoir volumes are quantified and compared with the impact of the uncertainty that is due to all the other modeling elements, e.g. petrophysical properties or fluid contact positions.
Velocity Modeling Facilities Include:
- Layer based and compartmentalized velocity model defined within the structural model
- Multi-scale model: integration of regional data and field data
- Display in 2D and 3D environment
- Stratigraphically constrained kriging and co-kriging
- Velocity calibration with well markers
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