Seismic Processing glossary

Clear, one-line definitions of the Seismic Processing terms used across the OgbonLab textbooks. Each entry links to the interactive sections where the idea is taught.

adaptive subtraction

A least-squares matching filter applied to a modeled noise (such as a predicted multiple) before subtracting it from the data, to absorb amplitude and phase mismatch.

See: Adaptive subtraction

adjoint

The transpose of the linearized forward modeling operator; used in migration and FWI as a cheap approximation to the true inverse.

amplitude fidelity

The degree to which processing preserves the true relative amplitudes of reflections, essential for AVO and quantitative interpretation.

autocorrelation

The correlation of a signal with a delayed copy of itself; reveals periodicities (such as multiples) and underlies Wiener spiking deconvolution.

ava

Amplitude versus angle: AVO expressed as a function of incidence angle θ rather than offset; the natural variable for the linearized Zoeppritz reflectivity.

avo

Amplitude versus offset: the variation of reflection amplitude with source-receiver distance, governed by the Zoeppritz equations and used as a fluid/lithology indicator.

cmp gather

A collection of traces sharing the same common-midpoint coordinate, used for velocity analysis, NMO correction, and pre-stack analysis.

convolved

Combined via the convolution operation, ∫ f(τ)g(t−τ)dτ; the seismic trace is the reflectivity series convolved with the source wavelet.

deconvolution

An inverse filter applied to seismic data to compress the source wavelet, suppress reverberations, and recover an estimate of the earth's reflectivity.

See: Predictive deconvolution, Surface-consistent deconvolution

demultiple

The processing step that identifies and removes multiple reflections (surface-related and internal) from seismic data.

See: Radon demultiple

depth migration

Migration that ray-traces or wave-propagates through an interval velocity model in depth, honoring lateral velocity variations and producing a depth image.

See: Pre-stack depth migration: Kirchhoff

design window

The time and offset window over which a deconvolution or filter operator is designed; should be quiet, signal-dominated, and stationary.

dmo

Dip moveout: a partial migration applied after NMO that corrects the offset-dependent reflection-point smearing caused by dipping reflectors.

f-k filter

A 2D filter in the frequency-wavenumber domain used to reject events with specific apparent velocities, such as ground roll or aliased noise.

fwi

Full-waveform inversion: a nonlinear least-squares method that iteratively updates a velocity model so simulated wavefields match recorded data sample-by-sample.

fx deconvolution

A noise-attenuation filter applied in the frequency-space (f-x) domain that exploits the predictability of laterally coherent signal versus random noise.

gather

Any organized collection of traces, by shot, receiver, CMP, or offset, used as the working unit for processing or analysis.

See: Synthetic AVO Gathers, Velocity picking on semblance gathers

ghost deconvolution

A filter that removes the source or receiver ghost, the surface-reflected delayed copy of the wavelet, to broaden the recorded bandwidth.

illumination

The angular and spatial coverage of subsurface reflectors by source-receiver raypaths; poor illumination produces gaps or shadows in the image.

image quality

A subjective and quantitative assessment of how clearly the migrated seismic image represents the true subsurface geometry and amplitudes.

inversion

Solving the inverse problem: estimating subsurface parameters (velocity, impedance, density) from observed seismic data, usually by minimising data misfit.

See: History Matching as Inversion, Tomographic velocity inversion

kirchhoff migration

An integral migration that sums data along diffraction surfaces (Kirchhoff-Helmholtz integral), one image point at a time, using a ray-traced traveltime table.

migration

An imaging step that repositions dipping reflections to their true subsurface location and collapses diffraction hyperbolae to their scattering points.

See: Migration artifacts & QC, True-amplitude migration

migration smile

A curved arc artifact produced by migrating an isolated noise sample; appears when migration spreads energy along the diffraction surface.

minimum-phase

A wavelet whose energy is concentrated as early in time as possible; the assumption underlying classical spiking deconvolution.

mute

The act of zeroing parts of a trace, such as early arrivals on far offsets (top mute) or noisy tails (bottom mute), before further processing.

nmo

Normal moveout: the extra travel time at offset x compared to zero offset for a horizontal reflector, approximately Δt ≈ x²/(2 t₀ V²).

operator length

The number of samples (or time span) of a digital filter such as a deconvolution operator; controls resolution and stability.

post-stack

Refers to data or processes applied after stacking, where only one trace per CMP remains (e.g., post-stack migration, post-stack attribute analysis).

See: Post-stack time migration

pre-stack

Refers to data or processes applied before CMP stacking, where individual offsets are still preserved (e.g., pre-stack migration, pre-stack inversion).

See: Pre-stack time migration (PSTM), Pre-stack depth migration: Kirchhoff

prediction lag

In predictive deconvolution, the gap between the input and the prediction; events at delays shorter than the lag are preserved, longer-delay events are removed.

predictive decon

Shorthand for predictive deconvolution: removes predictable periodic energy like reverberations, leaving the unpredictable primary reflectivity.

predictive deconvolution

A Wiener-based deconvolution that predicts and subtracts periodic events (such as short-period multiples) using a prediction lag set by their period.

See: Predictive deconvolution

q compensation

Inverse-Q filtering that compensates for frequency-dependent attenuation, restoring high-frequency content and correcting dispersion-induced phase shifts.

ray tracing

A high-frequency approximation that models wave propagation by tracing rays through a velocity model, solving the eikonal equation along each path.

ray-traced

Computed by ray tracing, modelling seismic wavefronts as rays that obey Snell's law at interfaces, used for traveltime modelling and migration.

refraction statics

Statics derived from first-break refractions through the weathering layer, used to align traces to a flat datum before stacking.

reprocessing

Applying modern processing algorithms (e.g., FWI, RTM, deghosting) to legacy data to improve resolution, signal-to-noise, and imaging.

rtm

Reverse-time migration: a two-way wave-equation migration that back-propagates the recorded wavefield through a velocity model and applies an imaging condition.

semblance

A normalized coherence measure computed along trial moveout curves; the peak in a semblance panel identifies the stacking velocity.

See: Velocity picking on semblance gathers

signal-to-noise

The ratio of coherent signal amplitude to noise amplitude on a seismic record; stacking and filtering aim to maximize it.

See: Noise and Signal-to-Noise

stacking

Summing NMO-corrected traces sharing a CMP to enhance primary reflections by √N and attenuate random noise that does not align.

See: Stacking, RMS, and interval velocities, Why stack, and why stacking is not enough

statics

Static (time-invariant) time shifts applied to traces to compensate for elevation, near-surface velocity, and weathering-layer variations.

See: First-break QC for statics, Refraction & tomographic statics

surface-consistent deconvolution

A decomposition that factors the trace wavelet into source, receiver, offset, and CMP terms, enabling consistent wavelet shaping across a survey.

See: Surface-consistent deconvolution

time migration

Migration performed in the time domain using a smoothly varying RMS velocity; fast and robust but inaccurate where lateral velocity changes are strong.

See: Post-stack time migration, Reverse-Time Migration (RTM)

tomographic statics

Statics derived from a near-surface velocity tomography inversion of first-break traveltimes, more accurate than simple delay-time methods in complex weathering.

See: Refraction & tomographic statics

velocity analysis

The process of estimating the stacking or migration velocity field from data, typically by maximizing semblance over CMP gathers.

vintage

A particular generation of a seismic dataset, defined by its acquisition and processing history; reprocessing creates a newer vintage.