|
<< Click to Display Table of Contents >> Navigation: Migration > Well tie |
The Well tie module adjusts an interval velocity model in depth so that it is consistent with known well-log velocities or depth markers. It uses a set of interpreted horizon picks that carry velocity correction factors at each horizon boundary. For every trace in the input velocity volume, the module computes a time-depth relationship, identifies the correction factors at each horizon, and scales the interval velocity between horizon boundaries accordingly. Traces that are far from any well location are gradually down-weighted so that the correction fades smoothly to zero beyond the taper radius.
Use this module after building a migration velocity model when well checkshots or sonic logs indicate a systematic depth mis-tie. The output is a corrected depth-domain velocity volume that can be used directly as input for depth migration or depth conversion.
The main data item connection for the processing sequence. Links this module to the preceding module in the workflow.
Link to the SEG-Y file handle used for reading the input seismic or velocity data.
Link to the trace header vector containing geometry information for each trace in the input volume.
Link to the input depth-domain interval velocity gather. Each trace in this gather corresponds to a single surface location and contains velocity values as a function of depth.
Link to the stack line geometry descriptor for 2D surveys.
Link to the crooked-line geometry descriptor for irregular or curved 2D survey lines.
Link to the 3D bin grid defining the spatial layout of the input velocity volume.
Link to the sorted trace header index used to access traces efficiently during processing.
Link to the horizon picking item that contains the well-tie correction layers. Each horizon in this set defines a depth (or two-way time) surface and carries a velocity correction factor derived from well-log data. The module reads the time and factor values for each horizon and uses them to rescale the interval velocity between consecutive horizon boundaries.
Time window (in seconds) below the deepest horizon over which the velocity correction is gradually tapered back to unity. This prevents abrupt termination of the correction at the base of the interpreted interval. Default: 0.25 s. Increase this value if you see artifacts directly below your deepest horizon boundary.
Maximum lateral distance (m) from the nearest well location beyond which the velocity correction is zero. Traces located farther than this distance receive no correction. Default: 5000 m. This value must be greater than the Prorogation taper min value.
Minimum lateral distance (m) from the nearest well within which the full velocity correction is applied without any distance-based attenuation. Between this radius and the maximum taper radius, the correction linearly decreases from full strength to zero. Default: 3500 m. Set this value smaller than the Prorogation taper max.
Hard upper limit (m/s) applied to the output corrected velocity. Any corrected velocity value that exceeds this limit is clipped to this value. Default: 6000 m/s. Set this to a geologically reasonable maximum to prevent unrealistic velocity spikes.
Hard lower limit (m/s) applied to the output corrected velocity. Any corrected velocity value that falls below this limit is clipped to this value. Default: 1500 m/s. Set this to the minimum geologically reasonable interval velocity for your survey area.
Path to a tab-delimited ASCII text file (.txt) listing the X and Y surface coordinates of each well location. Each line must contain two columns: X coordinate and Y coordinate. These positions are used to compute the lateral distance from each seismic trace to the nearest well, which controls the distance-based weight applied to the velocity correction. If no file is provided, all traces receive the full correction.
When enabled, the module automatically connects its input and output data items to compatible modules in the processing sequence, reducing manual wiring effort.
Determines how the module handles traces containing invalid amplitude values (NaN or infinity). Fix replaces bad values with zero before processing. Notify logs a warning and stops. Continue ignores the bad values and processes anyway.
Selects whether the module runs on the CPU or an available GPU. GPU execution can significantly accelerate processing for large velocity volumes.
Enables distributed (multi-node) processing. When active, the workload is split across multiple compute nodes in a cluster environment.
Minimum number of traces sent to each compute node in one batch during distributed execution. Larger values reduce inter-node communication overhead but require more memory per node.
When enabled, restricts the number of CPU threads used on each distributed node to the value set in the Number of threads parameter.
Optional text appended to the distributed job name to help identify individual runs in a cluster job queue.
When enabled, allows manual specification of CPU core affinity for the processing threads via the Affinity parameter.
Specifies the CPU core affinity mask used when Set custom affinity is enabled. This controls which physical CPU cores the processing threads are allowed to run on.
Number of CPU threads to use for parallel processing. Set to the number of physical cores available on the machine for best performance. The default uses all available cores.
When enabled, the module passes its input data through to the output unchanged without performing any processing. Use this option to temporarily disable the well tie correction in a workflow without removing the module.
The main data item output connecting this module to the next module in the processing sequence.
Link to the output SEG-Y file handle for writing the corrected velocity volume.
Link to the output trace headers carrying geometry information for the corrected velocity volume.
Link to the output gather containing the well-tied interval velocity volume in depth. This corrected velocity model can be passed directly to depth migration or depth conversion modules.
Link to the output stack line geometry descriptor for 2D surveys.
Link to the output crooked-line geometry descriptor for irregular 2D survey lines.
Link to the output bin grid passed to downstream modules.
Link to the output sorted trace header index passed to downstream modules.