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OpendTect Attributes Matrix

Abbreviations: OS=Open Source; OD=OpendTect; DS=Dip-Steering; NN=Neural Networks; HC=HorizonCube; CCB=Common Contour Binning; SCI=Seismic Colored Inversion; SSB=Seismic Spectral Bluing; SFE=Seismic Feature Enhancement; DI=Deterministic Inversion; MPSI=Multi-Point Stochastic Inversion; DHI=Direct Hydrocarbon Indicator; QI=Quantitative Interpretation; FF=Faults and Fractures


Note: Some attributes such as Similarity have open source and commercial versions. Detailed information about the Open Source version is given in the attribute name link while more information about the commercial version can be found under the Dip-Steered Attribute Name link.


Amplitude-based
Attribute Description Plugin Structural Stratigraphic Siliciclastics Carbonates Fluids Noise Other
Energy


References

Sum of Amplitudes Squared in a time-gate OS, OD Highlights packages with different reflection strengths Energy may correlate with lithology & porosity Enhances Bright Spots Use Sqrt output option to control output dynamic range
Scaling


References

Various functions to correct amplitudes vs. time OS, OD Scaling can be tuned to facilitate structural interpretation AGC time-gates smaller than 500ms should be avoided in quantitative interpretation Do not apply in workflows that require preservation of original amplitudes
Event


References
Quantifies the shape of an event or relative distance between events OS, OD Useful to determine horizon quality Useful inputs for 3D NN facies classifications
Stratal Amplitude


References
Returns statistical property (min, max, sum etc.) of an attribute in an interval defined along one horizon or between two horizons OS, OD Useful to characterize intervals
Frequency-based
Attribute Description Plugin Structural Stratigraphic Siliciclastics Carbonates Fluids Noise Other
Frequency


References
Returns a characteristic feature of an amplitude spectrum OS, OD Useful inputs for 3D NN facies classifications Frequency Slope Fall may pick up frequency loss below HC reservoirs Sweetness = RMS Energy / Average Freq. (construct with mathematics) may highlight hydrocarbons and thick sands
Instantaneous


References
Returns Instantaneous Attributes (amplitude, phase, frequency, and derivatives) OS, OD Amp. useful for sequence boundaries and thin bed tuning; Phase for pinch-outs, sequence boundaries,lapout patterns Amp. correlates with lithology & porosity Freq. indicator for fractured zones which show up as low frequency anomalies Freq. picks up HC associated low frequency anomalies; Amp. picks up bright spots
Spectral Decomposition


References
Decomposes a trace segment into frequency components (FFT) or Wavelet coefficients (CWT) OS, OD Picks-up thickness variations below seismic resolution caused by tuning; visualized on RGB(A) color-blended horizons; Useful inputs for 3D NN facies classifications Useful in analysis of channel systems and turbidites using seismic geomorphology Hydrocarbons may have a distinctive frequency signature. Gas anomalies typically associated with low frequency components Can be used to obtain information at high frequencies not normally believed to be useful Where there is a strong hydrocarbon signature masking the underlying geology the hydrocarbon signature may not be present at certain frequencies. These frequencies can be used to map geology.
Multi-trace Attributes
Attribute Description Plugin Structural Stratigraphic Siliciclastics Carbonates Fluids Noise Other
Similarity


References
Returns a value indicating how much two or more trace segments look alike OS,(DS) Visualize faults, salt edges Visualize abrupt pinch-outs ; erosional incisions; lateral variable lithofacies Visualize channels, point bar and barrier bar edges, can be used to identify mudflows from internal geometry Visualize reef edges, karst features, fracture zones Dip-steered Similarity is superior in dipping strata
Thinned Fault Likelihood


References
Returns the likelihood (0 and 1) of being a fault; Horizontal width is collapsed by thinning to one sample FF Visualize faults Visualize fracture zones when used as input to fracture density and fracture proximity attributes Input for automated fault plane extraction and un-faulting
Semblance


References
Returns semblance coefficient which is a meassure of multichannel coherence Visualize faults, salt edges Visualize abrupt pinch-outs; erosional incisions; lateral variable lithofacies Visualize channels, point bar and barrier bar edges, can be used to identify mudflows form internal geometry Visualize reef edges, karst features, fracture zones
Volume Statistics


References
Generic attribute returns a statistical property from a volume of data points OS,(DS) Core attribute in various user-defined filters, e.g. dip-steered median filter
Texture


References
Family of GLCM texture attributes from image processing to capture roughness / smoothness of the seismic response OS,(DS) Useful to capture variations in seismic facies either as stand-alone attributes, or as input to UVQ networks Visualize channels, lobes, slumps, flood plains etc. Visualize reefs, platforms, karsts, etc. Dip-steered Texture attributes should honor stratigraphy better than non dip-steered texture; Image anisotropy can be studied in all 13 possible directions
Fracture


References
Set of attributes to compute fracture properties OS, OD Helps in directly visualizing fracture properties from an input fracture-related discontinuity volume, such as curvature, similarity, semblance, texture etc. Characterize distance to the nearest fracture and proximity of individual fractures, as well as their density in a given area Proximity attribute may also be used to visualize the distance to the nearest DHI (e.g. a bright spot) defined on the basis of a simple seismic amplitude cutoff
Fault Extraction


References
Automated fault extraction work flow based on finger vein recognition algorithm (Start from Processing menu, or Volume Builder!) OS, DS Visualize faults score volumes and fault-orientations; extract fault sticks, or fault planes
Impedance-based
Attribute Description Plugin Structural Stratigraphic Siliciclastics Carbonates Fluids Noise Other
Absolute Acoustic Impedance


References
Model-driven deterministic inversion with stochastic add-on to evaluate uncertainties DI, MPSI Impedance is a layer property, tuning-effects are removed, pinch-outs are better visible AI often correlates with lithology, porosity and pore-fill; Absolute impedance values are a prerequisite in quantitative rock-property predictions; input to quantitative NNs Relation between AI and lithology, porosity and pore-fill is more variable and needs to be assessed on case by case basis Contacts may stand out better; pore-fill prediction is often possible Inverted data contains less random noise AI may be used for net pay estimation and assessing reservoir connectivity ; in presence of thin layers this is best done using the stochastic add-on
Relative Acoustic Impedance


References
Fast, band-limited Acoustic Impedance approach that optimally inverts data by globally honoring well information SCI Facilitates interpretation in geologic layers as opposed to interfaces Facilitates discrimination between hard and soft layers May pick up high-porosity sweet-spots in tight carbonate reservoirs Highlights contacts and DHI’s High-frequency noise is reduced Advantage: no exact well tie needed; With SNP plugin Net Sand or Net Pay can be mapped
Seismic Net Pay


References
Computes Net Pay or Net Sand from SCI input and top and bottom reservoir horizons SCI, SNP Designed for siliciclastic settings with relatively thin reservoirs
Extended Elastic Impedance


References
Inverts angle stack data to EEI; Target EEI well logs can be created in OD from Density, P-Sonic and S-Sonic. DI, MPSI, SCI Used to incorporate pre-stack information in QI work flows for better separation of lithologies and fluids May help separate true and false DHI anomalies
Dip & Azimuth-based
Attribute Description Plugin Structural Stratigraphic Siliciclastics Carbonates Fluids Noise Other
Dip


References
Computes dips in various directions and azimuth from a SteeringCube that stores inline - and crossline dip DS Polar dip is useful in fault interpretation; Apparent dip highlights faults in specified azimuth direction Incisions and undulations can be emphasized calculating a lateral gradient of the dip; angular unconformeties can be visualized calculating the vertical gradient of the dip Taking gradients (convolve attribute) from the dip often enhances interpretability; apply the volume statistics - variance attribute to the dip gives a measure of chaos
Curvature


References
Group of attributes derived from a SteeringCube that return how curved the dip field is DS Highlights faults and fracture zones, local morphologies (bowl, valley, ridge, dome). In extensional settings high curvature-density is an indicator for high fracture-density. In compressional settings high fracture-density occurs in flat areas with low curvature-density Might be used to detect differentially compacted features such as sand vs clay filled channels ; detects erosional incisions Useful to pick reef edges, karst features, identification of fractured zones Possible usage in fluid flow patterns
Processing & Filters
Attribute Description Plugin Structural Stratigraphic Siliciclastics Carbonates Fluids Noise Other
Mathematics


References
Attribute that returns the output of a user-defined formula, or logical expression OS, OD Used in many filters; complex chains of attributes can be computed; Supports Recursive filters (e.g. in Evaluate Attributes - default set)
Dip-Steered Median Filter


References
Edge-preserving smoothing filter; enhances laterally continuous events; removes random noise; default attribute set DS Facilitates structural interpretation, improves auto-tracker performance Removes random noise without smearing spikes Amplitude and edge preserving
Dip-Steered Diffusion Filter


References
Sharpens faults in seismic data; Pre-processing step for fault attributes, e.g. Similarity; default attribute set DS Facilitates structural interpretation; Should not be used in QI because amplitudes are shifted laterally Creates artifacts, best used as intermediate step to Fault Enhancement Filter
Fault Enhancement Filter


References
Evaluates the quality of the seismic data from Similarity; applies dip-steered median filter in good-quality data and a dip-steered diffusion filter in bad data zones (around faults); default attribute set DS Facilitates structural interpretation; sharpens the edges near discontinuities (faults), while smoothing else where; output has sharper faults and higher contrast between signal and background Erosional incisions are also enhanced
Smoothing


References
Structurally Oriented Filter that heavily smooths seismic without smearing across faults. Takes Thinned Fault Likelihood attribute as input FF Facilitates structural interpretation; Generates seismic with razor sharp edges
Seismic Spectral Blueing


References
Attribute that balances the seismic amplitudes within the bandwidth to match the well reflectivity spectrum SSB Small scale faults get better imaged Can create “ringing” if incorrectly applied Makes the amplitude spectrum “blue”: High frequencies have more energy that low energies.
Ridge Enhancement Filter


References
Sharpens ridges in a Similarity cube; Filter compares three neighboring similarity values in four different time-slice directions and outputs the largest ridge value; improves resolution OS, OD Facilitates structural interpretation Be aware of side lobes, clip at zero
Frequency Filter


References
Lowpass, Highpass and Bandpass FFT, or Butterworth filters OS, OD Facilitates structural interpretation Useful to remove frequency-related noise
Convolve


References
Group of filters that return the output of a convolution; Lowpass removes high frequencies and smooths the data; Laplacian is an edge-preserving filter; Prewitt returns the gradient which is used to enhance contrasts; Wavelet convolves the data with a wavelet OS, OD Facilitates structural interpretation Often used to enhance other attributes such as dip, similarity or curvature
GapDecon


References
Removes multiples from minimum-phase data with an inverse filter that aims to attenuate a user-defined part of the auto-correlation function; convert to minimum-phase: see Evaluate Attributes default set OS, OD Facilitates structural interpretation when multiples interfere with target horizons Facilitates stratigraphic interpretation in intervals contaminated with multiples GapDecon becomes a Whitening filter (=Spiking deconvolution) with lag=0
Velocity Fan Filter

References
3D filter to pass, or suppress energy with apparent velocities (Time surveys) or apparent dips (Depth surveys) OS, OD Useful e.g. to suppress flat multiples obscuring dipping primaries Can be tuned to suppress coherent noise with specific velocity (/ dip)
Match Delta & Delta Resample


References
Two attributes that together enable residual alignment of seismic volumes; Match Delta computes vertical shifts that are applied in Delta Resample OS, OD Residual alignment of multi-azimuth stacks, or NMO sub-stack before final stacking Residual alignment of Time-lapse volumes in 4D studies Can also be used to align sub stacks prior to avo calculations
Position


References
Returns any attribute calculated at the location where another attribute has its minimum, maximum or median within a small volume OS, OD Position is the key attribute in the design of a dip-steered diffusion filter
Reference Shift


References
Moves the evaluation position in 3D space; can be used to return Amplitude at [0,0] OS, OD Powerful combination with mathematics for designing special filters (e.g. ridge-enhancement)
Fluid Contact Finder


References
Stacks amplitudes along depth contour lines to enhance possible hydrocarbon effects FCF Enhances flat-spots and amplitude anomalies; pinpoints fluid contacts; powerful tool in exploration & appraisal to investigate untested blocks FCF pre-stack option enhances AVO effects; local FCF enhances 4D fluid-related effects
Seismic Feature Enhancement


References
Stacks traces along and across random lines to enhance flat-spots SFE Enhances flat-spots and amplitude anomalies in channels
Meta-Attributes
Attribute Description Plugin Structural Stratigraphic Siliciclastics Carbonates Fluids Noise Other
ChimneyCube


References
Highlights vertical disturbances in seismic data; Used in hydrocarbon migration path mapping and geohazard interpretation DS, NN Can discriminate active (vertically leaking) against passive (vertically sealing) faults Onset of chimneys may indicate source rock Highlights Thermobaric fluid paths (secondary porosity); Associated A-shapes indicate porosity decrease, V-shapes indicate karstification / increase Gas Chimney can derisk DHIs for low hydrocarbon saturation; positively identify hydrocarbon expulsion, migration and reservoir charge; predict oil vs gas phase reservoirs
FaultCube


References
Highlights major faults DS, NN Facilitates mapping of the structural framework User can chose between two input attribute sets; standard and advanced
SaltCube


References
Highlights salt bodies DS, NN Helpful in mapping the edges of salt domes
SlumpCube


References
Highlights slumped deposits DS, NN Mapping of slumps and turbidites
Fingerprint


References
Returns how similar the seismic response is to the response at user-defined locations; response is captured by user-defined attributes OS, OD Useful to find similar good reservoirs as encountered in certain wells Useful to find similar good reservoirs as encountered in certain wells Find similar responses as those at known oil and gas locations
UVQ Waveform


References
Clustering of seismic trace segments around a mapped horizon; available as Quick UVQ from horizon tree-menu NN Shows patterns in the interval that are associated with stratigraphy Picks up channels, lobes, levees, bars, etc. Picks up reefs, platforms, barriers, ramps, tidal flats etc. UVQ network can also output 3D volumes; Input attributes should then be phase-independent (no waveforms)
NN Classification


References
Supervised Neural Network Classification NN Alternative to UVQ; Difference is that patterns represent stratigraphic features the network was trained to recognize Classification of: good vs bad reservoirs; sands / silts / shales etc. Classification of: good vs bad reservoirs; reef / fore-reef / back-reef etc. Classification of: Gas / Oil / Brine Target well logs can be real, or simulated with the SynthRock plugin
NN Rock Property


References
Rock Properties predicted by MLP network that was trained on target well logs and impedance & seismic input volumes NN AI often relates to porosity and fluids. Vshale, Gamma-ray usually requires additional pre-stack input Porosity from AI is typically feasible Sw prediction may be possible with Acoustic Impedance, Elastic Impedance and Density inputs Target well logs can be real, or simulated with the SynthRock plugin
HorizonCube & SSIS-based
Attribute Description Plugin Structural Stratigraphic Siliciclastics Carbonates Fluids Noise Other
Systems Tracts ID


References
Assigns a unique ID to interpreted systems tracts for mathematical manipulations and visualization HC, SSIS Enables volume rendering of interpreted packages Unravel depositional architecture of channel systems Understand reef build-ups, platform architecture
Systems Tracts Isopach


References
Returns the thickness of the systems tract unit; helps to understand how sedimentation filled a basin as a function of geologic time HC, SSIS Used as color-overlay in Wheeler diagrams; enables study of depositional trends and sedimentation rates in space and time
HorizonCube Density


References
Returns the number of horizons in a continuous HorizonCube per time (depth) interval HC Highlights un-conformities and condensed sections Facilitates systems tracts identification Facilitates decomposition of carbonate build-ups
HorizonCube Thickness


References
Returns the thickness (in 2WT or depth) between consecutive horizons in a continuous HorizonCube HC Highlights variations in sedimentation patterns Useful in identification of un-conformities, condensed sections, pinchouts, slumps Highlights internal variations in carbonate build-ups
Pre-stack Attributes
Attribute Description Plugin Structural Stratigraphic Siliciclastics Carbonates Fluids Noise Other
AvO and AvA


References
Computes Intercept & Gradient from offset or angle gathers; Derived products from I & G and near-far stacks are available as default attribute sets OS, OD AvO / AvA analyses works best in loose, unconsolidated sands, but can be applied on more mature sands too (often AVO class I or II); can in select cases also be used for lithological prediction Due to the higher and more unpredictable variations of rock properties limited success in carbonates ; review applicability on case by case basis Primary DHI Well calibration and forward modeling/sensitivity analysis reduces uncertainty ; note sine2 axis transformation (4.4.0c and later) needs radians as input
Statistics


References
Returns a statistical property from gathers, e.g. to create (partial) stacks that can serve as input for derived AvO attributes from default attribute set OS, OD Re-stacking with new parameters may improve structural image Primary use is pre-processing for AvO attributes in QI work flows
Velocity Picking


References
Pick NMO or RMO velocities on gathers as input to Pre-Stack Depth Migration VMB Structural image is improved in an iterative process of velocity picking, gridding, and seismic migration. Updated velocities can be used to re-stack gathers
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Page last modified on January 26, 2016, at 08:45 AM