Geophysical Data Analysis 1

Course notes for the Geophysical Data Analysis 1 course (2025/2026 - 1) taught by Ayunda Aulia Valencia, S.T., M.T. and Agus Riyanto, M.Si. at the Department of Geoscience for BSc. in Geophysics. This course is divided into two classes, each taught by a different lecturer. While the overall learning objectives are aligned, there may be slight differences in the syllabus and course materials between the two.

flowchart TD
    A[/Raw Seismic Data/] --> B[Convert SEGY to SU]
    B --> C[/Raw Data SU Format/]
    C --> D[Apply Geometry]
    D --> E[/Geometry Applied Raw Data/]
    E --> F[Amplitude Recovery]
    F --> G[/Amplitude Corrected Data/]
    G --> H[F-K Filter]
    H --> I[/F-K Filtered Data/]
    I --> J[Band-Pass Filter]
    J --> K[/Band-Pass Filtered Data/]
    K --> L[Deconvolution]
    L --> M[/Deconvolved Data/]
    subgraph First Pass
    direction LR
        M --> |Sort to CDP| Z1[Velocity Analysis]
        Z1 --> Z2[NMO]
        Z2 --> |Satisfied ?| Z3[/NMO Corrected Data/]
    end

    M --> N[Elevation Statics Correction]
    N --> O[/Elevation Statics Corrected Data/] 
    subgraph Second Pass
    direction LR
        O --> |Sort to CDP| Z4[Velocity Analysis]
        Z4 --> Z5[NMO]
        Z5 --> |Satisfied ?| Z6[/NMO Corrected Data/]
    end

    O --> P[Residual Statics Correction]
    P --> Q[/Residual Statics <br/> Corrected Data/]
    subgraph Third Pass
    direction LR
        Q --> |Sort to CDP| Z7[Velocity Analysis]
        Z7 --> Z8[NMO]
        Z8 --> |Satisfied ?| Z9[/NMO Corrected Data/]
    end

    Z9 --> |Selected Velocity| T[Stacking]
    T --> U[/Stacked Data/]
    U --> V[Time Migration]
    V --> W[/Time Migrated Data/]
    W --> X[Convert SU to SEGY]
    X --> Y[/SEGY Output/]

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Prerequisites & Dependencies

• Seismic Un*x: Required for running the Seismic Un*x-related scripts and exercises. Installation instructions can be found at the Seismic Un*x website.
• Python 3.x: Necessary for running the Python scripts.
  • Libraries: Ensure you have the following libraries installed (using pip):
    • numpy
    • matplotlib
• MATLAB/Octave: For running the MATLAB/Octave scripts. Octave is recommended as a free alternative.
• A Linux/Unix-like environment: While some tools might work on Windows, the scripts are designed for a Unix-like environment (e.g., Linux, macOS, or WSL on Windows).

Installation & Setup Instructions

1. Clone the repository:

   git clone https://github.com/vandanue/ADG-1.git
   cd ADG-1

2. Seismic Un*x:

   • Make sure Seismic Un*x is installed and properly configured in your environment.
   • Verify that the $CWPROOT environment variable is set correctly.

3. Python Environment (Optional):

   • Create a virtual environment (recommended):

     python3 -m venv venv
     source venv/bin/activate  # On Linux/macOS
     # venv\Scripts\activate  # On Windows

   • Install the required Python packages:

     pip install numpy matplotlib

4. MATLAB/Octave:

   • Ensure MATLAB or Octave is installed on your system.
   • Octave is free and can be easily installed with your distribution's package manager (e.g., apt-get install octave).

Usage Examples

Applying Geometry using Octave

1. Navigate to the Scripts/1_geometry/matlab-octave/ directory.

2. Open geom_octave.m in Octave.

3. Run the script:

   octave:1> geom_octave

   This script requires the extract_geom_ps and geom_header_reg_offset.bin files to be present in the same directory.

Applying Geometry using Python

1. Navigate to the Scripts/1_geometry/python/ directory.

2. Open geometry.py.

3. Run the script:

   python geometry.py

Running Seismic Un*x Commands (Examples are within the note files)

Refer to the specific markdown files in the Notes/ directory for examples on how to use Seismic Un*x commands within shell scripts for tasks like gain testing and noise attenuation. Example usage is explained in each markdown file.

Configuration Options

• Most scripts can be configured by modifying variables directly within the script files (e.g., changing file paths, adjusting gain parameters, etc.).
• Seismic Un*x configuration is typically done through environment variables and parameters passed to SU commands. Refer to the SU documentation for more details.

Contributing Guidelines

1. Fork the repository.

2. Create a new branch for your feature or bug fix:

   git checkout -b feature/your-feature-name

3. Make your changes and commit them with descriptive messages.

4. Push your branch to your forked repository.

5. Create a pull request to the main repository.

License Information

This project has no license currently specified. All rights are reserved by the owner.

Acknowledgments

• The content of this repository is based on course materials from Geophysical Data Analysis 1 (SCGF603501).
• Seismic Un*x is a product of the Center for Wave Phenomena (CWP) at the Colorado School of Mines.