Attribute Matrix 2010[1]

Petrel* 2010 Attribute Matrix Seal Trap

Description

Reservoir Charge

Short Description and Meaning

Iso-Frequency

3D Curvature

Variance (Edge Method)

Dip Guided Variance

Filter

Dip deviation

PATENTED Spectral decomposition at user-selected frequencies. Obtained by cosine correlation transform (CCT) analysis that estimates the contribution of each frequency to the input seismic. By exploiting the tuning effects provides indications on stratigraphic thickness. N.B.: it works in time domain.

Structural attribute that describes how bent a curve is at a particular point. Enables the detection of subtle structural changes in dip-saturated data. Equivalent to the second-order derivative when the dip is zero.

Signal coherency analysis: Estimates trace to trace variance (1-semblance). Amplitude Invariant (but not orientation invariant); i.e. it will produce the same response for the same seismic signature, whether in a low or high-amplitude region.

Same as variance with an added principle component based guiding. Improves continuity of non-vertical events.

RMS Amplitude

Measure of reflectivity within a time window: The square root of the sum of the squared amplitudes divided by the number of live Samples

Remove Bias

Removes DC bias for the seismic traces. DC bias occurs when the average of the trace values departs from zero and may be caused by processing artifacts and/or geological factors.

Relative Acoustic Impedance

Physical attributes that reflects physical property contrast and provides better tie to well domain for geological analysis: Assumes zero phase data. Generated by integration of seismic trace and subsequent low cut filter to remove arbitrary long wavelength trends

Event, Gradient, Principle component

Local Structural Dip Event, Gradient, Principle component

Structural Smoothing Structural Smoothing Options: dip guide, edge enhance

Original Amplitude T* attenuation Chaos

Delineate Salt extents as separable from sediment on frequency content

Edge Detection (Structural)

Fault lineament detection, in particular in dip saturated data. Helps indentifying upthrown and downthrown sides of a fault

Reveals discontinuities in seismic data either related to stratigraphic Can help outline salt extents terminations or structural lineaments

Fault detection from continuous variance response. Gas chimney mapping

Reveals discontinuities in seismic data. As above, useful for structural and stratigraphic terminations.

Fault detection from continuous variance response. Gas chimney mapping

Can help outline salt extents

Formation Orientation

General Stratigraphic

Discerns flexure and position of anticline / syncline hinges

Detection of subtle depositional elements for seismic geomorphology such as channel incisions, gullies, incised valleys, drainage patterns and gas vents (negative curvature) or channel fills, splays, lobes, lens, isolated bars, mounds and wedges (positive curvature)

Must be a density change in channel fill and surrounds. Useful for channel development

Can discriminate between low and high continuity of seismic reflections. Interpretation of progradational versus aggradational stacking patterns on stratal slices.

High variance can suggest faults or fractures swarms

Useful for channel sweep at Z values for channel development

Can discriminate between low and high continuity of seismic reflections. Interpretation of progradational versus aggradational stacking patterns on stratal slices.

High variance can suggest faults or fractures swarms

Frequency filtered data is useful input for frequency based attributes.

Fault attribute enhancement and fault extraction

WARNING: the interior of a salt accumulation can be chaotic

Possible fracture indicator by local high dip deviation response

Delineate laterally continuous discontinuities based on a conditioned input

Large (seismic scale) fracture swarms detection

Derivative based attribute for stratigraphic and structural Provides information about the local application: The gradient for each voxel is calculated analytically by orientation field of the reflectors and its changes in the three directions the spatial derivatives in t/d, x and y directions

Input for edge detection like variance as it is amplitude sensitive

A measure of compass direction of the “normal” to the plane of the Captures structural orientation local seismic event

Second derivative

Reflection Intensity

Instantaneous Quality Time Gain

Genetic inversion

Dominant Frequency

Sweetness

Can be used as texture attribute for seismic facies analysis

Shows karsts and sinkholes, in addition to fracture corridors) and stratigraphic (carbonates build-ups/ reefs, channels, etc.) features

AVO Workflows

Hydrocarbon Indicator

Directional curvature can enhance the geology by suppressing footprints

Karst and sinkhole delineation. Good discriminator for seis- Detection and mapping of buildups/reefs within layer cake mic facies analysis depositional environments

Time gated frequency filter. Mute unwanted frequencies

Classical attribute for bright spot detection (highly correlated to Envelope)

Can differentiate between tight or shaly and good porosity limestone

Good discriminator for facies analysis

Provides better tie to lithology and can be related to porosity (non linear)

Discriminates weak coherent noise.

Use a wrapping colour map Captures stratigraphic orientation

A measure of the inclination of the seismic event measured from the horizontal plane

Captures structural dip

Define dipping direction of events

Performs data smoothing by local averaging with a Gaussian weighted averaging filter. Use as input for variance, dip deviation or chaos

General smoothing. Increased signal/ noise ratio for structural Interpretation

Use to remove noise from the data

Performs data smoothing by local averaging with a Gaussian weighted averaging along flow surfaces following the local dip/ azimuth

Shows the dip orientation of events

Captures stratigraphic dip

Help identify channel edges

Estimating local signal magnitude (absolute amplitude)

Provides increased layer continuity without sacrificing vertical resolution Increased signal/noise ratio

Enhance discontinuities

Can illuminate “flat spots” or fluid contacts

Used as possible data conditioning step before generation of variance attribute in Ant tracking workflow.

Delineate channel edges

The original amplitude of the seismic data

PATENTED Frequency attenuation-based algorithm which compares frequencies above and below selected points of analysis

Indicator of open fractures if gas is present

Open Fracture indicator

Maps the “chaoticness” of the local seismic signal from statistical analysis of dip/azimuth estimate.

Delineate Salt extents

Faults and fractures identification

Useful for identifying; Channel infill , Gas chimneys, Reef internal texture, Sink holes, Salt diapir, Shale diapir

Determines to which degree local orientation is planar

Good stratigraphic indicator: Reef internal texture Sink holes Channel infill in particular subtle features

Time derivative of the phase

First derivative

Can improve the image of subtle stratigraphic S/N can improve at selected features as well as frequencies sub-seismic faults

Lithology Indicator

Fracture corridors, Karst delinea- Filter using a stereonet to tion eliminate azimuthal features

Good stratigraphic discriminator

Bed thickness indicator and can detect lateral changes in lithology Laterally increasing instantaneous frequency can indicate bed thinning or pinch outs.

Trace AGC

Can be used as input to facies mapping in particular for seismic geomorphology analysis

Stratigraphic layering. High contrast indicates possible sequence boundaries, Reveals unconformity surfaces

Reveals discontinuities and improves structural delineation

Detect lithological changes, Sequence boundaries, Thin-bed tuning effects

Graphic Equalizer

Noise Reduction

Removes DC bias from the trace

Mainly represents the acoustic impedance contrast, hence reflectivity. Indicates the group, rather than phase component of the seismic wave propagation.

Apparent Polarity

Carbonates

Detects amplitude variations for channels with density changes to surrounds

Envelope (Reflection Strength)

Instantaneous Phase

Texture Attribute

Filtered seismic can show channels clearer

Discriminates rapid changes in Use in softer lithologies local orientation. where the downthrown Input to Ant Tracking side of the fault shows dip

Local Flatness

Cosine of Instantaneous Phase

Channels

High curvature zones especially on the Maximum Curvature are often associated with high fracture density zones.

Maps the “flatness” of the local seismic signal, 3D. “Flatness” is the degree to which local reflectors are flat/planar (not necessarily horizontal).

Instantaneous Frequency

Fracture Indicator

Selected frequencies, also combined with other Identification of thin beds and subtle stratiattributes in a ANN, can graphic features (e.g. pinch-out, reefs, chandetect possible fractures zones For channel mapping and nels, etc.). via attenuation analysis, or, thickness estimation Can be used along stratal slices for seismic geoconversely can highlight submorphology analysis seismic faults

Selected frequencies can provide sharper image of small faults than the input data for input to workflows such as Ant Tracking.

Detects subtle changes in structural trend and/or tectonic features and lineaments, convex up (positive curvature) or concave down (negative curvature) structures

Edge detection attribute: Estimates difference between sample dip and local dip. A threshold can be applied.

Ant Tracking

Local Structural Azimuth

Can enhance subtle structural features.

Salt Workflow

Apply a frequency filter over time gates to seismic data. Various methods and tapers are available

PATENTED Fault enhancing attribute. Connects attribute responses by using principles of swarm intelligence (“ants”)

Gradient Magnitude

General Structural

Cosine function applied to the instantaneous phase

Description of the phase angle at any instant along a trace independent of amplitude. It reveals weak and strong events with equal strength

Continuity boundary of sediment at salt face

Improves lateral continuity of layers

Continuity boundary of sediment at salt face

Discriminator for geometrical shape Good indicator of continuities, angular unconformities, faults, pinch-outs, sequence boundaries, onlap patterns

Can help when used in combination to isolate faults

Channel infill

High pass filter enhances terminations and discontinuities for fault mapping. Low pass filter enhances signal/noise to improve seismic event continuity.

High pass filter enhances terminations and discontinuities for fault mapping

Detection and mapping of buildGood discriminator for seis- ups/reefs within mic facies analysis Layer-cake depositional environments.

Spatial correlation to porosity and other lithologic variations

Fracture zone indicator, since fractures may appear as lower frequency zones

Enhances low amplitude sections for improved horizon interpretation Drawback is that relative amplitude information is lost

Time rate of change of the amplitude

Useful for Stratigraphic analysis, facies estimation, QC interpretation (zero crossing)

Second derivative measures the variation in the tangents of the selected seismic amplitude, directly above and below the reflection. High values indicate rapid shift from peak to trough (short wavelength)

Second derivative can be used to help guiding the pick by providing continuity in areas of where reflections are poorly resolved on the raw amplitude May help resolve subtle stratigraphic patterns such as shingled/low angle prograding fore-sets

May enhance terminations and discontinuities

A quality factor that is assigned based on the instantaneous envelope

Can be used for fracture Detection

Show onlap and channel edges via frequency filtering

May help distinguish different kinds of bright spots (due to gas, limestone..)

Reduce frequencies from noisy seismic

Boosts weak events but also boosts noise

Can help isolate channels features

In combination with Envelope, useful for (Near—Far) / Near

Karst delineation

Can indicate fluid content and absorption character of a reservoir

Can be used for fracture detection Helps identify time dependant weaknesses in seismic amplitudes

Enables the balancing of amplitudes as a function of time. If the gain is >1 amplitudes will increase with time and if gain is