AVO Attributes Calculation Quiz

NMO correction = Correction of seismic traces to match reflection arrival times Residual NMO = Distortion of AVO response due to inaccurate velocity analysis Interference effects = Caused by reverberations or 'multiples' in seismic wavefield Noise attenuation techniques = Methods to effectively reduce interference with primary amplitudes

Attenuation and dispersion = Changes in amplitude due to wave spreading or subsurface interactions NMO stretch = Broadening of wavelet shape at further offsets Correctly focusing and positioning = Achieving desired primary signal while correcting for noise Tuning effects = Can cause interference in the primary wavefield

Residual NMO correction requires denser velocity analysis = To reduce the impact of distorted AVO response Reverberations and multiples cause interference in wavefield = Resulting from interactions with subsurface interfaces Processing techniques aim to preserve primary amplitudes = While effectively attenuating noise Migration step corrects for moveout in data processing = By aligning events across a gather

AVO analysis = Qualitative tool used to detect anomalies Migration step = Corrects moveout and aligns events in data processing Calculation of Intercept and Gradient = Extraction of seismic amplitudes for analysis Residual Moveout correction = Addresses distortion of offset-dependent reflectivity

Noise removal = Denoising techniques NMO correction = Time variant corrections Trace Muting = Elimination of bad traces Amplitude preservation = True-amplitude processing

Wave propagation effects = Geologic effects Acquisition effects = Noise effects Processing artifacts = Impact on AVO analysis

Estimate and remove energy losses = Preserve seismic wave amplitudes Remove noise effects = Ensure data accuracy Avoid processing artifacts = Maintain data integrity

Wave propagation and geologic effects = Natural seismic wave behavior Acquisition and noise effects = External interference during data collection Processing artifacts = Errors introduced during data processing

Review factors affecting seismic amplitudes = Understand variables influencing seismic data Discuss processing related issues = Analyze challenges in seismic data manipulation

Amplitude-preserved processing = Techniques maintaining original signal strength True-amplitude processing = Methods ensuring accurate amplitude representation

Residual moveout = Addressed to make events flatter Ground roll = Has very high amplitude and low velocity NMO stretching = Affects offset-dependent reflectivity Trace Mute = Limits influence of long offset traces for optimum stack

Energy losses removal = Part of seismic-data processing for AVO analysis Noise effects removal = Part of seismic-data processing for AVO analysis Near surface effects removal = Part of seismic-data processing for AVO analysis Avoid processing-related artifacts = Part of seismic-data processing for AVO analysis

Residual NMO = Distorts offset-dependent reflectivity NMO stretching = Distorts offset-dependent reflectivity Noise removal effect = Can lead to distortion of AVO response Muting in traditional processing = May restrict maximum range of angle used in AVO analysis

Great variability in amplitudes = Seen before post-imaging processing Consistent plots after processing = Seen after post-imaging processing Class 3 AVO response mismatch = Observed in near and middle angle range Synthetic AVO response mismatch = Observed in near and middle angle range

Limit influence of long offset traces = For producing optimum stack Deals with high amplitude noise = In traditional processing Deals with NMO related issues = In traditional processing Recommended for AVO analysis muting = Should be done separately from stack generation

High amplitude and low velocity = Characteristics of ground roll Distorts near-offset traces = May cause false AVO interpretation Significant decrease in primary amplitudes = Result of aggressive ground roll removal Restricts range of offsets or angles for AVO analysis = May be caused by ground roll

AVO intercept = Measures the zero-offset response AVO gradient = Measures the rate of change of amplitudes with offset Higher order moveout = Incorporates 4th order NMO term related to anisotropy and velocity heterogeneity Conventional Trim Statics = Calculates a single time shift for each trace in a gather to align traces within a time window

Gather flattening using NMO = Constrained by the Normal Moveout equation Conventional Trim Statics = Limited to their calculation windows, making it difficult to align separated events Time-Variant Trim Statics = Performs cross-correlation calculation over smaller, overlapping windows and interpolates the shifts Trim Statics - Strengths and Weaknesses = Simple and fast to apply, but may result in unrealistic shifts due to lack of physical model

Correct velocity for NMO correction = Results in flat gathers with correct amplitude and phase for AVO intercept and gradient Incorrect velocity for NMO correction = Causes non-flat gathers and incorrect amplitude extraction at peak of wavelets Two term NMO application = Refers to applying the first 2 terms of the NMO equation defined by Tsvankin and Thompsen 4th order NMO term = Related to anisotropy and/or velocity heterogeneity, raises velocity to the 4th power

Comparison between 2-term and higher term NMO curves = Shows variations from -20 ms to +50 ms, with greatest deviation at far offsets Example from Ross illustrating higher order move-out effect = Shows how higher order correction produces flatter gathers compared to two term NMO Impact of higher order move-out terms on seismic events = Includes a 4th order NMO term related to anisotropy and velocity heterogeneity Difference in events alignment before and after trim statics application = Highlights how trim statics can improve alignment within analysis window but may not address events outside of it

NMO Stretch = Time variant stretch functions leading to frequency distortion SuperGather = Tool for reducing random noise and preserving offset-dependent amplitude variations AVO Analysis = Methodology to analyze seismic data for amplitude variations with offset Ground Roll = Strong linear noise energy affecting near offsets

Trim Statics = Subject to quality control and considered in the context of AVO class type Random Noise = Described as anything not considered useful signal, can be reduced by forming SuperGathers Coherent Noise = Includes multiple energy causing amplitude effects varying with offset Anomalous AVO Gradients = Obscured by conventional NMO correction, can be removed by addressing NMO stretch

NMO Correction = Stretches traces as a function of time and offset to prevent frequency distortion Noise Attenuation = Removes unwanted noise to improve Signal-to-Noise ratio Stacking = Combines seismic traces to enhance signal clarity Imaging = Post processing step after which additional multiple attenuation may be applied

Far Offset Muting = Restricts range of angles and increases error in estimated AVO attributes Ground Roll Amplitude Distortion = Affects near offsets and interferes with primary AVO measurement Amplitude Effect from Multiples = Varies with offset and affects the amplitude of primary signal events Anomalous AVO Gradients = Indicates anomalies that can affect resolution of stack

SuperGather = Reduces random noise and preserves offset-dependent amplitude variations NMO Stretch Correction = Attempts to remove effect of NMO stretch to improve seismic data quality Multiple Attenuation = Minimizes impact of multiples on AVO analysis results AVO Analysis Tool = Analyzes amplitude variations with offset to extract geological information

Supergathers = Formed by stacking adjacent gathers in a spatial configuration to reduce random noise Gradient Section = Illustrates AVO results before and after addressing NMO stretch effect CMP Gather = Shows predicted AVO response before post-imaging processing Forward Modeled Gather = Synthetic representation showing expected AVO behavior

Far Offset Muting Application = Prevents lower frequency events from affecting stack resolution NMO Stretch Addressing Methodologies = Aim to keep information from far offsets and mitigate NMO distortion Multiple Attenuation Procedure = Reduces impact of interfering energy on primary signal amplitude AVO Analysis Limitations Mitigation Process = Seeks to expand range of angles and reduce error in estimated AVO attributes

Random Noise = Can be reduced by forming SuperGathers to improve Signal-to-Noise ratio Coherent Noise = Includes energy causing interference that varies with offset, impacting AVO analysis Linear Noise Energy (Ground Roll) = Affects near offsets and interferes with primary signal, impacting true AVO measurement Incoherent Noise = Obscures flat seismic events and needs to be removed for clarity in analysis

AVO Attributes = Quantities derived from the Amplitude Variation with Offset analysis. NMO Stretch Function = Time variant stretch functions leading to frequency distortion. Stack Resolution = The level of detail or clarity in a stacked seismic image. Amplitude Effect from Multiples = Varying amplitude impact caused by multiple reflections.

Trim Statics Quality Control = Ensures accurate interpretation considering expected AVO class type. SuperGather Preservation = Maintains offset-dependent amplitude variations while reducing noise. Ground Roll Interference = Affects near offsets, impacting true primary AVO measurement. Anomalous AVO Gradients Removal = Eliminates anomalies that can affect stack resolution.