Wave Modelling

/app/wave-modelling/new

Set up and run a two-dimensional finite-difference simulation of seismic waves through the project's earth model, then browse the recorded gathers and download the outputs. Each layer takes a scenario from Rock Physics Modelling or its baseline properties, and a finished run leaves shot gathers, VSP records and snapshots to view here and files to download for use outside the app.

Job

The bar above the model view where a run is named and started.

Field	Purpose	Range	Default
Job name	The name the run is filed under in the results list. Choose something that tells you apart from other runs later; it must begin with a letter or digit.	2 to 25 characters letters, digits, hyphens and underscores, starting with a letter or digit	—

Limits are the API's unless marked app. The app may offer a narrower range.

Grid

Expert mode, Input Parameters tab: the spacing of the model in space and time.

Field	Purpose	Range	Default
Grid Increment	Spacing between neighbouring grid points, the same in both directions. Finer spacing resolves shorter wavelengths and thinner layers, at a higher computational cost.	0.1 to 100 m	5 m
Time Step	Time between successive steps of the simulation. It must be small enough for the grid spacing and the fastest velocity in the model, otherwise the simulation becomes unstable.	0.000001 to 1 s	0.0002 s

Limits are the API's unless marked app. The app may offer a narrower range.

Grid Size

Expert mode, Input Parameters tab: how many grid points the model spans and how many of them form the absorbing edge.

Field	Purpose	Range	Default
Total X Grid Points	Number of grid points across the model, including the absorbing boundary on each side. Together with the grid spacing this sets the model width.	at least 10app	961
Total Z Grid Points	Number of grid points down the model, including the absorbing boundary at the base. Together with the grid spacing this sets the model depth.	at least 10app	481
X Absorbing Points	Thickness, in grid points, of the absorbing zone on the left and right edges. A thicker zone suppresses artificial reflections from the model edges but takes space from the useful part of the model.	at least 0app	50
Z Absorbing Points	Thickness, in grid points, of the absorbing zone at the base of the model. A thicker zone suppresses artificial reflections from the bottom edge.	at least 0app	50

Limits are the API's unless marked app. The app may offer a narrower range.

Time

Expert mode, Input Parameters tab: how long the simulation runs.

Field	Purpose	Range	Default
Time Steps	Number of time steps the simulation runs for. Multiplied by the time step it gives the record length; more steps let the wavefield travel further and cost more to compute.	at least 1app	16001

Limits are the API's unless marked app. The app may offer a narrower range.

Source

Expert mode, Input Parameters tab: what kind of source is fired and where it sits in the model.

Field	Purpose	Range	Default
Number of Sources Point Source (1) Gaussian Array (9)	Whether the source is a single point or a small Gaussian-weighted cluster of points. A cluster gives a smoother, more directional source with fewer grid artefacts.	—	Gaussian Array (9)
Source Type P source traction (0) X velocity source (1) Z velocity source (2)	How the source excites the medium: as a pressure (P-wave) traction, or as a velocity push in the horizontal or vertical direction. Velocity sources generate stronger shear energy.	—	P source traction
Source X Position	Horizontal position of the source, measured from the left edge of the model.	at least 0 mapp	2400 m
Source Z Position	Depth of the source, measured from the top of the model. A shallow source mimics a surface survey; a deeper one places the shot inside the medium.	at least 0 mapp	0 m

Limits are the API's unless marked app. The app may offer a narrower range.

Receivers

Expert mode, Input Parameters tab: the horizontal line of receivers that records the surface gather.

Field	Purpose	Range	Default
Receiver Spacing	Distance between neighbouring receivers along the line. Closer spacing gives more traces and avoids spatial aliasing of steeply dipping events.	at least 0.1 mapp	20 m
Receiver Start X	Horizontal position of the first receiver, measured from the left edge of the model.	at least 0 mapp	2400 m
Receiver End X	Horizontal position of the last receiver, measured from the left edge of the model. With the start position and spacing this fixes how many traces the gather holds.	at least 0 mapp	4780 m
Receiver Depth	Depth of the receiver line below the top of the model. Keep it at the surface for a conventional gather or bury it to record inside the medium.	at least 0 mapp	0 m

Limits are the API's unless marked app. The app may offer a narrower range.

VSP

Expert mode, Input Parameters tab: optional vertical receiver arrays. The four list fields hold one value per array, in the same order.

Field	Purpose	Range	Default
VSP Arrays	How many vertical receiver arrays to record. Leave it at zero for a surface-only survey; each array adds a VSP gather to the outputs.	0 to 1000	1
VSP Depth Spacing	Vertical spacing between receivers in each array, one value per array. Closer spacing gives a denser VSP gather.	m, up to 1000 values	20 m
VSP X Coordinates	Horizontal position of each array, measured from the left edge of the model, one value per array.	m, up to 1000 values	2400 m
VSP Start Depths	Depth of the shallowest receiver in each array, measured from the top of the model, one value per array.	m, up to 1000 values	20 m
VSP End Depths	Depth of the deepest receiver in each array, measured from the top of the model, one value per array.	m, up to 1000 values	1900 m

Limits are the API's unless marked app. The app may offer a narrower range.

Snapshots

Expert mode, Input Parameters tab: wavefield images saved while the simulation runs.

Field	Purpose	Range	Default
Number of Snapshots	How many images of the whole wavefield to save during the run. They become the frames of the snapshot animation in the downloads.	at least 0app	501
First Snapshot	The time step at which the first snapshot is taken. Delay it to skip the early part of the run before the wavefront has left the source.	at least 1app	31
Snapshot Interval	Number of time steps between successive snapshots. A smaller interval gives a smoother animation over a shorter span of the run.	at least 1app	31

Limits are the API's unless marked app. The app may offer a narrower range.

Run Parameters

Expert mode, Run Parameters tab: the source wavelet. The fields shown depend on the wave type chosen.

Field	Purpose	Range	Default
Wave Type Ricker wavelet (0) User defined wavelet (3)	Whether the source fires a Ricker wavelet described by its peak frequency, or a wavelet you supply sample by sample.	—	Ricker wavelet (0)
Peak frequency ^*	Peak frequency of the Ricker wavelet. Higher frequencies resolve thinner layers but need a finer grid and attenuate faster.	0 to 1000 Hz	35 kHz
Time applied to wavelet ^*	How long the Ricker wavelet is applied at the source. Leave it at zero to let the wavelet run its natural length.	at least 0 s	0.09092 seconds
Array of amplitude values	The samples of your own wavelet, as a list of amplitudes in time order. Used only when the wave type is user defined.	1 to 10000 values	—
Sample interval ^*	Time between successive samples of your own wavelet. It tells the simulation how to place the amplitudes in time.	over 0 s	0 seconds

Limits are the API's unless marked app. The app may offer a narrower range.

* Peak frequency: the app shows unit kHz; the API accepts unit Hz.

* Time applied to wavelet: the app shows unit seconds; the API accepts unit s.

* Sample interval: the app shows unit seconds; the API accepts unit s.

Plots

The Plots tab: choose which finished runs and gathers to view, on their own or side by side.

Field	Purpose	Range	Default
plot-job Select a job…	The finished run to display in this slot. Fill the second slot as well to compare two runs.	—	—
plot-gather	Which gather of the chosen run to display, when the run recorded more than one of the current survey type.	—	—
Surface Surface VSP	Whether to show the surface receiver line or a vertical (VSP) array. Offered only when the run recorded both.	—	Surface
Surface Vx Vz	Which recorded wavefield component to display, such as pressure or a particle-velocity direction.	—	Vz

Limits are the API's unless marked app. The app may offer a narrower range.

Seismic Viewer

Display controls above the gather on the Plots tab. They change how the traces are drawn, not the data.

Field	Purpose	Range	Default
Gain None tpow (t^p) AGC Per-trace norm (pbal) Scale Bias	How trace amplitudes are balanced before drawing: none, a power-of-time ramp, automatic gain control, per-trace normalisation, a fixed scale or a fixed offset.	—	None
p	Exponent of the power-of-time gain. Larger values boost late, weak arrivals more strongly.	0 to 5app	2
win	Length of the sliding window used by automatic gain control. A shorter window equalises amplitudes more aggressively.	0.01 to 2 sapp	0.5 s
Gain	Factor every amplitude is multiplied by when the scale gain is chosen.	—	2
Gain	Constant added to every amplitude when the bias gain is chosen, shifting the traces left or right of their zero line.	—	0
Max Amplitude	Overrides the amplitude at which traces are clipped. The value found in the data is shown beside it; leave it empty to use that.	—	—
Clip	Percentile of the absolute amplitudes used as the clip level. Lower values clip more of the strongest samples so weaker events stand out.	90 to 100 %app	99 %

Limits are the API's unless marked app. The app may offer a narrower range.

Download Files

The Results tab: the output files of the run selected in the job list.

Field	Purpose	Range	Default
file-select-all	Selects or clears every file in the list for a single download.	—	false
file-select	Marks one file for download. Selected files are fetched together with the download button above the list.	—	—

Limits are the API's unless marked app. The app may offer a narrower range.