Acquisition and Processing of Marine Seismic Data

Description

Acquisition and Processing of Marine Seismic Data demonstrates the main principles, required equipment, and suitable selection of parameters in 2D/3D marine seismic data acquisition, as well as theoretical principles of 2D marine seismic data processing and their practical implications. Featuring detailed datasets and examples, the book helps to relate theoretical background to real seismic data. This reference also contains important QC analysis methods and results both for data acquisition and marine seismic data processing. Acquisition and Processing of Marine Seismic Data is a valuable tool for researchers and students in geophysics, marine seismics, and seismic data, as well as for oil and gas exploration. Front Cover Acquisition and Processing of Marine Seismic Data Copyright Dedication Contents Chapter 1: Introduction 1.1. Underwater Acoustics 1.2. Marine Acoustic Methods 1.2.1. Bathymetric Systems 1.2.2. Side-Scan Sonar 1.2.3. Subbottom Profiler 1.2.4. Single Channel and Multichannel Seismics 1.2.5. Yesterday/Today/Future of Seismic Exploration at Sea 1.3. Fundamentals of Marine Seismics 1.3.1. Seismic Waves 1.3.2. Reflection From an Interface 1.3.3. Shot Gathers 1.3.4. Reflection Hyperbolas Chapter 2: Marine Seismic Data Acquisition 2.1. Components of Marine Seismic Acquisition 2.1.1. Seismic Vessels 2.1.2. Hydrophones and Streamer 2.1.3. Marine Seismic Energy Sources 2.1.4. Gun Control Systems 2.1.5. Streamer Depth Controllers 2.1.6. Seismic Recorder 2.1.7. Integrated Navigation System 2.1.8. Tail Buoys, Dilt Floats and Paravanes 2.1.9. Lead-in and Deck Cables 2.2. Air Gun Arrays 2.2.1. Air Gun Principles 2.2.2. Air Gun Bubble Effect 2.2.3. Ghost Reflection 2.2.4. Near-/Far-Field Source Signatures 2.2.5. Cluster/String/Array 2.2.6. Tuning and Array Performance 2.3. 3D Marine Seismic Acquisition 2.3.1. Acquisition Patterns 2.3.2. Streamer Steering 2.3.3. Streamer Layout 2.3.4. Acoustic Network 2.3.5. Flip-Flop Shooting 2.3.6. Slant Streamer Acquisition 2.3.7. Fan Mode Acquisition 2.3.8. Multiazimuth Surveys 2.4. Specific Acquisition Techniques 2.4.1. Ocean Bottom Seismic Acquisition 2.4.1.1. Ocean Bottom Cable 2.4.1.2. Ocean Bottom Seismometer 2.4.1.3. Ocean Bottom Nodes 2.4.2. Time-Lapse (4D) Seismic 2.4.3. Transition Zone Acquisition 2.4.4. P-Cable Acquisition 2.5. Data Acquisition Parameters 2.5.1. Parameters for Survey Geometry, Sources, and Receivers 2.5.1.1. Shot Interval 2.5.1.2. Streamer/Source Depth 2.5.1.3. Group Interval 2.5.1.4. Offset Distance 2.5.1.5. Sail Line Azimuth 2.5.1.6. 2D and 3D Coverage 2.5.1.7. Bin Size 2.5.1.8. Line Interval and Infill 2.5.1.9. Run-In and Run-Out Distances 2.5.1.10. Air Gun and Array Parameters 2.5.1.11. Tow Distance and Vessel Speed 2.5.2. Parameters for Data Recording 2.5.2.1. Record Length 2.5.2.2. Sampling Rate 2.5.2.3. Recording Filter Cut-Off Frequencies 2.5.2.4. Dynamic Range and Seismic Sample Format 2.5.2.5. Optimum Fold 2.6. QC in Data Acquisition 2.6.1. Preacquisition Instrument Tests 2.6.1.1. Tests for Navigation System and Components 2.6.1.2. Tests for Seismic System and Streamer 2.6.1.3. Tests for Gun Array and Components 2.6.2. Analysis of Seismic Data 2.6.3. Analysis of Navigation Data 2.6.4. Analysis of Seismic Source 2.6.5. QC Reporting 2.6.5.1. Mobilization Report 2.6.5.2. QC Reports Per-Line 2.6.5.3. Daily Reports 2.6.5.4. Weekly and Monthly Reports 2.6.5.5. Final Survey Report 2.6.5.6. HSE Report 2.6.5.7. Final Deliverables Chapter 3: Noise in Marine Seismics 3.1. Operational Noise 3.2. Bubble Effect of the Air Gun 3.3. Multiple Reflections 3.4. Swell Noise 3.5. Bird Noise 3.6. Inline Waves 3.6.1. Tail Buoy Noise 3.6.2. Mechanical Cable Noise 3.6.3. Direct Waves 3.6.4. Refracted Waves 3.7. Diffractions 3.8. Guided Waves 3.9. Seismic Interference 3.10. Other Noise Types 3.10.1. Powerline Harmonic Noise 3.10.2. Spikelike Noise 3.10.3. Side-Sweep 3.10.4. Noise From Other Marine Vehicles 3.10.5. Marine Mammals 3.10.6. Streamer Ballasts Chapter 4: Fundamentals of Data Processing 4.1. Autocorrelation 4.2. Crosscorrelation 4.3. Convolution 4.4. Fourier Series 4.5. 1D Fourier Transform 4.6. 2D Fourier Transform 4.7. z Transform 4.8. Hilbert Transform 4.9. τ-p Transform (Slant Stack) 4.10. Sampling Theory Chapter 5: Preprocessing 5.1. Demultiplexing 5.2. Data Loading 5.3. Single Trace Section 5.4. Geometry Definition 5.4.1. QC in Geometry Loading 5.5. Band-Pass Filter 5.5.1. Filter Operator 5.5.2. Band-Pass Filtering of Marine Seismic Data 5.5.3. Time Varying Filtering 5.5.4. QC in Band-Pass Filtering 5.6. Gain Recovery 5.6.1. Spherical Divergence Correction 5.6.2. Time Raised to a Power Correction (tP) 5.6.3. Automatic Gain Control 5.6.4. QC in Gain Recovery 5.7. Trace Edit 5.8. Muting 5.8.1. QC in Muting 5.9. f-k Dip Filters 5.9.1. f-k Filtering of Marine Seismic Data 5.9.2. QC in f-k Filtering 5.10. Brute Stack Chapter 6: Deconvolution 6.1. Convolutional Model 6.2. Assumptions for Deconvolution 6.2.1. Assumption 1: A Simple Earth Model 6.2.2. Assumption 2: Stationary Wavelet 6.2.3. Assumption 3: Noise Component 6.2.4. Assumption 4: Source Waveform 6.2.5. Assumption 5: Wavelet Causality 6.2.6. Assumption 6: Random Reflectivity 6.3. Spiking Deconvolution 6.3.1. Deconvolution With Inverse Filter 6.3.2. Inverse Filtering With Least Squares 6.3.3. Optimum Wiener Filters 6.3.4. Prewhitening 6.4. Predictive Deconvolution 6.5. Determination of Deconvolution Parameters 6.5.1. Autocorrelation Time Gate 6.5.2. Deconvolution Design Gate 6.5.3. Operator Length 6.5.4. Prediction Lag 6.6. Poststack Deconvolution 6.7. Maximum Entropy (Burg) Deconvolution 6.8. Shaping Filters 6.9. Surface Consistent Deconvolution 6.10. QC in Deconvolution Chapter 7: Suppression of Multiple Reflections 7.1. CDP Stack 7.2. Predictive Deconvolution 7.3. Deconvolution in τ-p Domain 7.4. Radon Velocity Filter 7.5. Wave Equation Multiple Rejection 7.6. f-k Filtering 7.7. Surface-Related Multiple Elimination 7.8. QC in Multiple Suppression Chapter 8: CDP Sort and Binning 8.1. CDP Geometry 8.2. CDP Fold 8.3. Binning in 3D 8.4. QC in Sort and Binning Chapter 9: Velocity Analysis 9.1. Types of Seismic Velocity 9.1.1. Interval Velocity (Vint) 9.1.2. Average Velocity (Vave) 9.1.3. Instantaneous Velocity (Vins) 9.1.4. Root-Mean-Square Velocity (VRMS) 9.1.5. NMO or Stacking Velocity (VNMO) 9.1.6. Dix Interval Velocity (VDIX) 9.2. Velocity Determination From Seismic Data 9.2.1. Constant Velocity Scan 9.2.2. Constant Velocity Stack 9.2.3. Velocity Spectra 9.3. Velocity Analysis in Practice 9.3.1. Supergather 9.3.2. Effect of Reflection Depth 9.3.3. Effect of Streamer Length 9.3.4. Effect of Fold Number 9.3.5. Effect of Multiple Reflections 9.3.6. Effect of Time Gate 9.3.7. Effect of Velocity Increment 9.3.8. Effect of Semblance Sample Rate 9.3.9. Effect of Noise 9.3.10. Effect of Muting 9.4. QC in Velocity Analysis Chapter 10: Normal Moveout Correction and Stacking 10.1. Normal Moveout Time 10.1.1. NMO Time for Single Horizontal Interface 10.1.2. NMO Time for Several Horizontal Interfaces 10.1.3. NMO Time for Dipping Interfaces 10.1.4. NMO Corrections for Long Offsets 10.1.5. NMO Velocity in Azimuthally Anisotropic Medium 10.2. NMO Stretching 10.3. Stacking 10.4. Specific Stacking Methods 10.4.1. Partial Stack 10.4.2. Median Stack 10.4.3. Trimmed Stack 10.4.4. Common Reflection Surface Stack 10.5. QC in NMO Correction and Stacking Chapter 11: Seismic Migration 11.1. Migration Concept 11.1.1. Effects of Migration 11.1.2. Types of Migration 11.2. Kirchhoff Migration 11.2.1. Migration Aperture 11.2.2. Maximum Dip Restriction 11.2.3. Effect of Velocity on Kirchhoff Migration 11.3. Finite-Difference Migration 11.3.1. Depth Step Size 11.3.2. Effect of Velocity on Finite-Difference Migration 11.4. Frequency-Wavenumber (f-k) Migration 11.4.1. Stolt Stretch Factor (W) 11.4.2. Effect of Velocity on f-k Migration 11.5. Reverse Time Migration 11.6. Poststack Migration 11.7. Prestack Migration 11.8. Depth Migration 11.9. 3D Migration 11.10. Dip Moveout 11.11. Which Migration to Use? 11.12. QC in Migration Chapter 12: Specific Methods 12.1. f-x Prediction Filter (f-x Decon) 12.2. Median Filter 12.3. Trace Mixing 12.4. Time-Variant Spectral Whitening 12.5. Instantaneous Attributes 12.6. Amplitude vs. Offset 12.6.1. AVO Equations 12.6.1.1. Zoeppritz Equations 12.6.1.2. Aki-Richards Approximation 12.6.1.3. Shuey Approximation 12.6.2. Intercept and Gradient 12.6.3. AVO Classes 12.6.3.1. Class I (Dim Out) AVO Anomalies 12.6.3.2. Class II (Phase Reversal) AVO Anomalies 12.6.3.3. Class III (Bright Spot) AVO Anomalies 12.6.3.4. Class IV AVO Anomalies 12.6.4. Processing Considerations for AVO 12.6.5. AVO Analysis 12.6.5.1. Partial Stack 12.6.5.2. Gradient Analysis 12.6.5.3. AVO Attributes 12.6.5.4. AVO Crossplots References Index Back Cover