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Note: This module is deprecated. It is retained for compatibility with existing workflows.
This module generates a synthetic multi-focusing (MF) model dataset by ray-tracing from a layered velocity model defined by the user. Given a seismic geometry (trace index list and bin grid), the module shoots rays through a model consisting of flat horizontal layers with a constant or periodically fluctuating near-surface velocity and uniform sub-surface layers. The resulting synthetic gathers are written to an output SEG-Y file and can be used to test and calibrate the multi-focusing search engine workflow.
The trace index vector providing the source-receiver geometry for which synthetic traces will be modelled. This connects the module to the seismic loop or to an existing dataset index so that the module knows which shot-receiver combinations to model.
The bin grid that defines the spatial layout and coordinate system of the survey area. The modelling module uses the bin grid to compute midpoint and offset positions for each trace.
The near-surface (weathering layer) velocity (m/s) used as the reference velocity for the upper portion of the model. The default is 2000 m/s. This value sets the velocity of the layer above the first reflector defined by the layer table.
When enabled (default: true), a spatially constant near-surface velocity equal to V0 is used throughout. When disabled, a spatially periodic velocity fluctuation is superimposed on V0 to simulate lateral velocity variations in the weathering layer.
The spatial period (m) of the near-surface velocity fluctuation pattern applied when Use Const Velocity is disabled. The default is 1000 m. A larger value produces a more gradual lateral velocity variation.
The amplitude (m/s) of the near-surface velocity fluctuation when Use Const Velocity is disabled. The velocity at each point will vary between V0 − Amplitude and V0 + Amplitude over the spatial period.
The thickness (m) of the near-surface layer assigned velocity V0. The default is 100 m. Below this depth, the velocity transitions into the layered model defined by the layer parameters.
The initial ray azimuth (radians) for the modelling geometry. Use 0 for rays propagating in the inline direction. Adjust this to match the acquisition azimuth of the modelled survey.
The initial emergence angle (radians) for the modelled rays. This parameter controls the subsurface dip direction of the modelled reflectors. Use 0 for horizontal reflectors.
The initial curvature parameter (radians) of the modelled wavefront, corresponding to the initial gamma angle in the multi-focusing parameterisation. For flat horizontal reflectors set this to 0.
The number of horizontal reflectors in the layered model. The default is 1. Each layer generates one set of reflection arrivals in the output synthetic. Each layer is separated by a time step of Layer Step dt0.
The two-way time interval (s) between successive reflectors. The default is 0.1 s. The first reflector is placed at Initial t0, and each subsequent reflector is placed at an additional Layer Step dt0 deeper.
The two-way zero-offset arrival time (s) of the shallowest reflector. The default is 1 s. Deeper reflectors are placed at t0 + n × Layer Step dt0 for each layer n.
The number of time samples in each output synthetic trace. The default is 1000. The total trace length equals Number of samples × Sample ratio. Ensure the trace length is sufficient to accommodate all reflectors defined by the layer model.
The time sample interval (s) of the output synthetic traces. The default is 0.004 s (4 ms). Match this to the sample rate of the real seismic data against which the synthetic model will be compared.
When enabled (default: true), all source and receiver elevations are set to zero, producing a flat-datum synthetic without elevation statics. Disable this to incorporate the actual surface topography from the geometry when modelling land surveys with significant elevation variation.
The path and filename for the output SEG-Y file containing the modelled synthetic gathers. Browse to the desired output directory and enter a filename with the .sgy extension.
Container for the source wavelet parameters used to convolve with the modelled reflection response. Three sub-parameters are defined: ImpulseType selects the wavelet shape (Ricker1 is recommended for most tests); Frequency (Hz) sets the dominant frequency; and WaveLen (s) sets the total wavelet window length.