Seismic Data Details
Raw seismic records are infested with many types of random and coherent noises. Different noise elimination routines are used to effectively remove these noises – resulting in effective signal processing, signal to noise ratio improvement and better imaging.
- Shot Gather before Noise Suppression
- Shot Gather after Noise Suppression (De-spiking, Time Frequency Domain noise suppression, Linear Noise Attenuation with Adaptive Filtering)
- Difference of A and B
Refraction Based Static Correction
For land data Static correction plays a vital role. It is crucial for hilly terrain data where near surface whether layer velocity and depth varies rapidly. Up hole based static correction may not be adequate. Refraction based inversion on picked first breaks from the regular seismic profile may better capture variations in refractor depth (A), weathering and sub-weathering velocity (B). More meaningful static correction to datum may be computed from the near surface velocity-depth model thus arrived.
For optimum migration, optimum stack response it is desirable that all the offset bins are filled with live data. For variety of reasons traces are missing giving holes in data. 3D regularization fills the missing traces per offset bin through borrowing/intelligent interpolation with the neighboring live traces (A a, b). This results in fold harmonization along lines/bins (B a , b) in the 3D grid area.
Surface Related Multiple Elimination (SRME), a powerful tool to remove multiples derived from the air/water interface can be implemented successfully. Whole process of estimation and removal of the multiple energy through SRME approach is done in following five steps –
Geometry regularization (the spatial sampling) within each shot record, starting with extrapolation of the trace data to “zero offset” and ensuring the spatial sampling (offset interval) between traces is a constant increment.
Estimate or “model” the multiples.
Geometry un-regularization to restore the “modelled multiple” records to the same spatial sampling as the original recorded shots.
Design and apply a match ﬁlter that matches the modeled multiples to the recorded shots.
Adaptive Subtraction to “ﬁne tune” the match between pairs of traces (estimated multiple trace and original recorded trace), then subtract the multiple trace from the original trace.
RTM is an ideal solution for complicated wave propagation and imaging tasks, especially for complex media with steep dip salt boundaries. AGT RTM is fully capable of handling all imaging projects, from isotropic to anisotropic, from narrow azimuth to wide/full azimuth.
- Low memory requirement for large-scale problems
- No compromise in accuracy (e.g., high-order FD, PML boundary condition, shear wave suppression, split wave field for better imaging)
- High-quality 3D RTM angle gather with high frequency (e.g. 50Hz 3D)
- Output every location in offset or angle domain as necessary
Tomographic Velocity Models are especially valuable for generating quality subsurface images of geographic dynamics in complex locations. AGT algorithms speed up tomographic inversion, producing accurate images quickly.
- High-resolution tomography for small velocity anomalies
- Superior fault definition and improved image
- Global automatic residual depth move-out picking
- Geology structural conformed inversion
- Sub-salt velocity update with RTM angle gathers
- Unique FWI algorithm that does not require low-frequency data
- Insensitive to source estimation error and data measurement error
- Novel efficient implementation of the Hessian Matrix to accelerate convergence rate
- Highly automatic and adaptive parameter tuning algorithms requiring minimum user interaction
- Optimized workflows designed for various categories of seismic data
PSDM and PSTM are reliable and powerful imaging technologies ideally suited to less complex media, or for fast track imaging and final imaging for noisy land datasets. AGT implements these technologies with the latest GPUs to deliver superior performance and dramatically reduce the velocity building turnaround time.
- Unique implementation for efficiency and turnaround
- Designed for large 3D datasets and high resolution imaging
Seismic wave simulation is a valuable tool used to verify acquisition design and address key interpretation risks. To overcome the high computation costs associated with 3D wide azimuth survey seismic wave simulation, AGT has developed a proprietary patent-pending implementation on GPU that allows us to run these simulations cost effectively.
- Large scale seismic modeling capability
- Finite Element and Finite Difference
- Surface/Seafloor topography (Deep Water, Shelf, 4D studies, cross-well)
- Variable gridding (1600x2000x1300 elastic grid)
- Full physics (Acoustic/Elastic, ISO/VTI/TTI/Orthorhombic, Q)
- VSP/Sea floor multi-component recording
- Support from isotropic to anisotropic, from acoustic to elastic, from narrow azimuth to full/wide azimuth