Seismic Data Processing Techniques Quiz

AVO Attributes Calculation

• Noise Attenuation Techniques: Methods to effectively reduce interference with primary amplitudes
• Residual NMO Correction: Distortion of AVO response due to inaccurate velocity analysis
• Interference Effects: Caused by reverberations or 'multiples' in seismic wavefield

Seismic Data Processing

• Correctly Focusing and Positioning: Achieving desired primary signal while correcting for noise
• NMO Stretch: Broadening of wavelet shape at further offsets
• Attenuation and Dispersion: Changes in amplitude due to wave spreading or subsurface interactions
• Tuning Effects: Can cause interference in the primary wavefield

Residual NMO Correction

• Purpose: To reduce the impact of distorted AVO response
• Requirement: Denser velocity analysis

Migration Step

• Purpose: Corrects moveout and aligns events in data processing
• Role: By aligning events across a gather

Seismic Data Preparation

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

Seismic Processing Issues and Solutions

• Noise Removal: Denoising techniques
• NMO Correction: Time variant corrections
• Amplitude Preservation: True-amplitude processing
• Trace Muting: Elimination of bad traces

Factors Affecting Seismic Amplitudes

• Wave Propagation Effects: Geologic effects
• Acquisition Effects: Noise effects
• Processing Artifacts: Impact on AVO analysis

AVO Analysis

• Objectives:
  • Preserve seismic wave amplitudes
  • Ensure data accuracy
  • Maintain data integrity
• Types of Phenomena Distorting Seismic Amplitudes:
  • 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

Amplitude-Controlled Processing

• True-Amplitude Processing: Methods ensuring accurate amplitude representation

• Amplitude-Preserved Processing: Techniques maintaining original signal strength### Seismic Data Quality Improvement

• NMO Stretch Correction attempts to remove the effect of NMO stretch to improve seismic data quality.

• Multiple Attenuation reduces random noise and preserves offset-dependent amplitude variations.

Seismic Data Types

• Supergathers are formed by stacking adjacent gathers in a spatial configuration to reduce random noise.
• Forward Modeled Gather is a synthetic representation showing expected AVO behavior.
• Gradient Section illustrates AVO results before and after addressing NMO stretch effect.
• CMP Gather shows predicted AVO response before post-imaging processing.

Seismic Workflow Steps

• 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.
• Far Offset Muting Application prevents lower frequency events from affecting stack resolution.
• AVO Analysis Limitations Mitigation Process seeks to expand the range of angles and reduce error in estimated AVO attributes.

Noise Types and their Impact

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

Seismic Attributes

• AVO Attributes are quantities derived from the Amplitude Variation with Offset analysis.
• NMO Stretch Function is a time variant stretch function leading to frequency distortion.
• Stack Resolution is the level of detail or clarity in a stacked seismic image.
• Amplitude Effect from Multiples is the varying amplitude impact caused by multiple reflections.

Seismic Concepts and their Impact on Data Interpretation

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