The purpose of seismic processing is to manipulate acquired data into an image or set of images of the subsurface geology. Processing consists of applying a sequence of routines on a computer guided by a geophysical processor. There is no single correct processing sequence for a given data. Many stages throughout processing require judgements and decisions to be made which are often subjective, and rely on the processors experience or bias. It is wise that an interpreter should be involved at all stages to check that processing decision do not radically alter the interpretability of the result in a detrimental manner.
A further article many be useful for guidelines for specific processing problems encountered in various geologic provinces.
- 1 Contractors
- 2 Processing flow
- 3 Testing
- 4 A simple example marine processing flow
- 5 A simple example of a land processing flow
- 6 Prestack processing flows
- 7 AVO processing flows
- 8 VTI and TTI processing flows
- 9 HTI AVAZ processing flows
- 10 Orthorhombic processing flows
- 11 Seismic inversion
- 12 References
Most commercial seismic data processing is carried out by contractors who are able to perform most jobs quickly and cheaply with specialized staff, software, and hardware. The following is a not-exhaustive list of geophysical contractors who specialize in seismic data processing
|WesternGeco||Large||3D, marine||Promax (?)||Many|
A processing flow is a collection of processing routines strung together and applied to a data volume. Most processing routines accept input data, apply a process to it and produce output which is saved before passing it to the next processing stage. Several of the stages are strongly interdependent and each of the processing routines will require several parameters to be chosen or defaulted. Some parameters will be defined, for instance, by the acquisition geometry and some must be determined for the particular data being process by the process of testing. Parameter choices are almost always subjective, but a good rule of thumb is to keep things as simple as possible unless there is a reason suggesting otherwise.
A simple example marine processing flow
A simple example of a land processing flow
List of operations, more or less the order in which they could be applied. Not all of them are necessary.
True amplitude recovery (e.g. T1.5)
Filter (minimum phase equivalent of sweep)
Surface consistent scaling
Refraction statics applied to a floating datum
Surface consistent scaling
Velocity analysis (a second round)
Surface consistent residual statics (a second round)
Time and spatially varying mute
Non-surface consistent statics
DMO velocity analysis
Post-stack time migration
Output: Post-stack time migration volume
Prestack processing flows
AVO processing flows
VTI and TTI processing flows
HTI AVAZ processing flows
Azimuthally sorted gathers have sinusoidal perturbations about an average RMS velocity. The sinusoid represents the magnitude of the travel time variation between the fast and slow orientation 'above' the reflection event. The phase of the sinusoid can be used to extract the orientation, and the amplitude can be used to determine the ellipticity or eccentricity of the seismic HTI anisotropy.