26 articles
Amplitude versus offset
Amplitude versus offset (AVO) is a seismic analysis technique that measures how reflected wave amplitude changes with source-receiver distance, used as a direct hydrocarbon indicator.
Amplitude versus offset analysis
Amplitude versus offset (AVO) analysis measures how seismic reflection amplitude changes with source-receiver offset, and uses that variation to constrain subsurface rock properties and fluid content, notably free gas.
Bottom simulating reflector
A bottom simulating reflector (BSR) is a seismic reflection in marine sediment that mimics the seafloor and crosscuts layers, commonly indicating gas hydrate below continental margins.
Geostatistical inversion
Geostatistical inversion is a stochastic seismic inversion method, introduced in 1993, that generates multiple equiprobable property models conditioned to seismic data and well logs, quantifying uncertainty.
Imaging condition
An imaging condition is the mathematical rule combining forward-propagated source and backward-propagated receiver wavefields into a subsurface reflectivity image, the final step of seismic migration.
Least-squares migration
Least-squares migration (LSM) is a seismic imaging method that iteratively inverts a forward modeling operator to produce images with fewer artifacts, truer amplitudes, and higher resolution than conventional migration.
Migration velocity analysis
Migration velocity analysis (MVA) is a seismic imaging method that estimates the subsurface velocity model by repeatedly migrating data, measuring kinematic errors in prestack images, and tomographically inverting them into velocity updates.
Multichannel analysis of surface waves
Multichannel analysis of surface waves (MASW) is a seismic method, introduced by Park, Miller, and Xia in 1999, that estimates near-surface shear-wave velocity from Rayleigh-wave dispersion and is widely used in geotechnical engineering.
Normal moveout
Normal moveout (NMO) is a seismic data processing correction that time-shifts each trace in a CMP gather by an offset-dependent amount, flattening reflections for stacking.
Ocean bottom node (seismic)
An ocean bottom node is an autonomous seismic receiver placed on the seabed to record air-gun energy, offering wider azimuth and cleaner data than towed streamers.
Ocean-bottom node
An ocean-bottom node (OBN) is a cable-free seismic receiver placed on the seafloor that records data autonomously on battery power and is retrieved for download, offering wide-azimuth imaging advantages.
Pre-stack depth migration
Pre-stack depth migration, or PSDM, is a seismic imaging technique that migrates unstacked traces into a depth image using a velocity-depth model, correctly positioning reflectors under salt and complex structure.
Reverse time migration
Reverse time migration (RTM) is a seismic imaging method that propagates recorded wavefields backward in time using the full two-way wave equation, introduced in the early 1980s.
Seismic attribute analysis
Seismic attribute analysis is a geophysics method that extracts quantitative measures from seismic reflection data to characterize subsurface structure, stratigraphy, and fluid content, revealing faults without hand picking.
Seismic attributes
A seismic attribute is a quantity extracted or derived from seismic data, such as amplitude or frequency, analyzed to enhance subtle information and improve geological interpretation.
Seismic facies analysis
Seismic facies analysis is a geophysical interpretation method that classifies groups of seismic reflections into mappable facies units, inferring depositional environments, lithofacies, and reservoir properties of the subsurface.
Seismic migration
Seismic migration is a geophysical imaging method that repositions recorded seismic reflection events to their true subsurface locations, producing an image of geological structures in the Earth's interior.
Seismic refraction
Seismic refraction is a geophysical surveying method that infers subsurface layer velocities, depths, and dips from refracted wave travel times; it was the first seismic technique used in oil exploration.
Seismic survey
A seismic survey is a geophysical exploration method that generates seismic waves and records reflected returns, imaging subsurface rock layers for oil, gas, and mineral exploration.
Seismic survey vessel
A seismic survey vessel is a specialized ship that tows acoustic sources and hydrophone streamers to image rock layers beneath the seabed, mainly for offshore oil and gas exploration.
Spectral decomposition (seismic)
Spectral decomposition in seismology is a family of time-frequency analysis methods that breaks a seismic trace into its frequency components, revealing bed thickness variations, discontinuities, and fluid effects.
Velocity analysis (seismology)
Velocity analysis is a seismic processing method estimating subsurface velocities from how reflection arrival times vary with source–receiver offset, producing a velocity spectrum of semblance values.
Velocity model building
Velocity model building is the process of constructing a 3D model of seismic wave speeds in the subsurface, iteratively updated so depth migration images reflectors at their true positions.
Vibroseis
Vibroseis is a seismic surveying method in which a truck-mounted hydraulic vibrator radiates a frequency-modulated signal into the ground, replacing explosives; it was developed by Conoco in the 1950s.
Viridien
Viridien, known as CGG (Compagnie Générale de Géophysique) until its 2024 rebrand, is a French geoscience, seismic imaging, and Earth data company headquartered in Paris, with about 3,500 employees worldwide.
Well tie
A well tie, or seismic-well tie, is the alignment of a synthetic seismogram computed from well logs with the actual seismic trace at the borehole, linking depth to time.