Geophysical Data Visualization Demo - User Guide

Overview

The geophysical demo (examples/scientific/geophysical_demo.xdl) is a comprehensive workflow that demonstrates XDL’s capabilities for 3D seismic data analysis and visualization. It generates synthetic seismic data with realistic geological features and provides interactive 3D visualization.

Features

Data Generation

  • 3D Seismic Cube: 64×64×32 volume (configurable)
  • Geological Structures:
    • Anticline (dome) structure for hydrocarbon trapping
    • Normal fault with vertical offset
    • Multiple stratigraphic layers
  • Realistic Physics: Reflection coefficients, wavelet modeling

Analysis Capabilities

  1. Section Extraction
    • Inline sections (constant X)
    • Crossline sections (constant Y)
    • Time slices (constant Z)
  2. Seismic Attributes
    • Instantaneous amplitude
    • Vertical gradient
    • Horizontal gradient (fault indicator)
  3. Automated Interpretation
    • Fault detection via gradient analysis
    • Horizon auto-picking
    • Structural interpretation
  4. Statistical Analysis
    • Amplitude statistics
    • Signal-to-noise ratio
    • Frequency content estimation
  5. 3D Volume Visualization
    • Interactive ray-casting volume renderer
    • Configurable colormap (Rainbow, Viridis, etc.)
    • Real-time rotation, zoom, and pan
    • Threshold and opacity controls

Running the Demo

Basic Execution 

# Run the complete demo with 3D visualization
xdl examples/scientific/geophysical_demo.xdl

Environment Variables 

# Use specific VIZ3D backend
VIZ3D_BACKEND=threejs xdl examples/scientific/geophysical_demo.xdl

# Available backends:
# - threejs (default): Three.js WebGL (best compatibility)
# - webgpu: Native WebGPU renderer
# - browser: Browser-based WebGPU

Workflow Steps

Step 1: Survey Parameters 

Survey dimensions:  64 x 64 x 32
Inline spacing:     25.0 m
Crossline spacing:  25.0 m
Time sampling:      4.0 ms

Step 2: Geological Model

Creates stratigraphic layers:

  • Layer 1: Shallow sediments (0-30ms)
  • Layer 2: Sandstone reservoir with anticline (30-50ms)
  • Layer 3: Faulted shale cap (50-70ms)
  • Layer 4: Deeper formations (70-128ms)

Step 3: Seismic Data Generation

Generates synthetic seismic amplitudes with:

  • Reflection wavelets at layer boundaries
  • Anticline geometry (petroleum trap)
  • Normal fault with ~20ms throw
  • Realistic noise

Step 4-6: Section Extraction

Extracts representative sections:

  • Inline section at mid-position
  • Crossline section through anticline
  • Time slice at reservoir level (40ms)

Step 7: Seismic Attributes

Computes diagnostic attributes:

  • Instantaneous amplitude (envelope)
  • Vertical gradient (layer boundaries)
  • Horizontal gradient (fault indicator)

Step 8: Fault Detection

  • Gradient-based fault probability map
  • Identifies fault location and orientation
  • Estimates fault throw

Step 9: Horizon Tracking

  • Auto-picks reservoir horizon (40ms ± 10ms)
  • Tracks anticline structure
  • Computes structural relief

Step 10: Structural Interpretation

Analyzes geological features:

  • Anticline closure area (km²)
  • Structural relief (ms)
  • Fault characteristics (type, throw, location)

Step 11: Amplitude Analysis

  • Extracts amplitude at reservoir level
  • Interprets hydrocarbon indicators
  • Classifies reflection strength

Step 12: Data Quality

Assesses seismic data quality:

  • Mean amplitude and standard deviation
  • Signal-to-noise ratio
  • RMS amplitude
  • Frequency content estimation

Step 13: 3D Volume Visualization ✨

Interactive 3D rendering of the seismic cube:

  • Window: 1280×720 HD display
  • Colormap: Rainbow (shows amplitude variations)
  • Camera: Positioned for optimal viewing angle
  • Volume: Full 64×64×32 seismic cube
  • Features visible: Anticline and fault structures

3D Visualization Controls

When the 3D viewer opens:

Mouse Controls

  • Left Click + Drag: Rotate camera around volume
  • Mouse Wheel: Zoom in/out
  • Right Click + Drag: Pan camera

GUI Controls

The viewer includes sliders for:

  • Threshold: Filter low-amplitude values
  • Opacity: Adjust transparency
  • Colormap: Switch color schemes
  • Camera Reset: Return to default view

Keyboard Shortcuts

  • ESC: Close viewer
  • Space: Pause/resume rotation (if auto-rotating)
  • R: Reset camera to default position

Output Example 

> Step 13: Launching 3D visualization...

VIZ3D: Initialized (1280x720)
  Volume loaded:  64  x  64  x  32
  Amplitude range: [ -0.1 ,  0.9 ]

  Rendering 3D seismic cube...
  - Blue/negative: Troughs (possible hydrocarbon indicators)
  - Red/positive: Peaks (strong reflections)
  - Structures: Anticline and fault visible in volume

🚀 Launching Three.js volume visualization...
Controls:
  - Left mouse: Rotate camera
  - Mouse wheel: Zoom in/out
  - GUI sliders: Adjust threshold and opacity

✓ Three.js volume visualization launched
  Volume: 64×64×32
  Colormap: RAINBOW

✓ 3D visualization complete!

Key Results

Typical output from the demo:

Key Features Identified:
  • Anticline closure area:  0.996 km²
  • Structural relief:  14.3 ms
  • Normal fault with ~20ms throw
  • Reservoir reflection amplitude:  -0.099

Data Quality:
  • Signal-to-noise ratio:  6.27
  • RMS amplitude:  0.149
  • Dominant frequency: ~80 Hz

Geological Interpretation

Anticline Structure

The synthetic data includes a classic 4-way closure anticline:

  • Structural trap for hydrocarbons
  • ~14ms of structural relief
  • Closure area of ~1 km²
  • Visible in all three orthogonal views

Normal Fault

A normal (extensional) fault cuts through the structure:

  • Vertical throw: ~20ms
  • Orientation: North-South strike
  • Location: Inline position ~800m
  • Creates footwall and hanging wall compartments

Reservoir Characteristics

The reservoir layer (30-50ms) shows:

  • Moderate amplitude reflection
  • Consistent across anticline crest
  • Potential for hydrocarbon accumulation

Technical Implementation

Array Operations

Uses XDL’s multi-dimensional array support:

seismic = FLTARR(nx, ny, nz)  ; 3D array
min_val = MIN(seismic)         ; Works on entire volume
max_val = MAX(seismic)         ; No manual loops needed
mean_val = MEAN(seismic)       ; Direct computation

VIZ3D Functions Used 

VIZ3D_INIT, WINDOW_SIZE=[w, h], TITLE='...'
VIZ3D_COLORMAP, 'RAINBOW'
VIZ3D_CAMERA, POSITION=[x,y,z], TARGET=[x,y,z], FOV=45.0
VIZ3D_VOLUME, data, DIMENSIONS=[nx,ny,nz]
VIZ3D_RENDER, /INTERACTIVE, TITLE='...'

Performance

  • Generation: ~2-3 seconds for 64³ volume
  • Analysis: ~1 second for all attributes
  • Rendering: Real-time (60fps) with Three.js

Customization

Change Volume Size 

; Larger volume (higher resolution)
nx = 128
ny = 128
nz = 64

; Smaller volume (faster execution)
nx = 32
ny = 32
nz = 16

Modify Geological Features 

; Stronger anticline
anticline_relief = 20.0  ; instead of 15.0

; Larger fault offset
fault_offset = 30.0  ; instead of 20.0

Different Colormap 

VIZ3D_COLORMAP, 'VIRIDIS'  ; or 'PLASMA', 'TURBO', etc.

Applications

This demo illustrates workflows for:

  1. Seismic Interpretation
    • Structural mapping
    • Fault identification
    • Horizon picking
  2. Petroleum Exploration
    • Trap identification
    • Reservoir characterization
    • Prospect evaluation
  3. Educational Use
    • Teaching seismic interpretation
    • Understanding 3D data visualization
    • Learning XDL programming
  4. Algorithm Development
    • Testing attribute algorithms
    • Validating auto-picking methods
    • Benchmarking visualization
  • medical_imaging_demo.xdl - CT/MRI visualization
  • viz3d_demo1_gaussian.xdl - Simple 3D Gaussian blob
  • viz3d_demo3_turbulence.xdl - Turbulent flow visualization

Next Steps

To extend the demo:

  1. Import Real Data: Replace synthetic data with SEG-Y files
  2. Advanced Attributes: Add coherence, curvature, etc.
  3. Well Integration: Incorporate well log data
  4. Quantitative Analysis: Reservoir property estimation
  5. Time-Lapse: Compare 4D seismic surveys

Technical Requirements

  • XDL interpreter with VIZ3D support
  • ~50MB RAM for 64³ volume
  • WebGL-capable GPU (for Three.js backend)
  • Modern web browser (embedded Tauri window)

Troubleshooting

Visualization doesn’t appear 

# Check backend selection
VIZ3D_BACKEND=threejs xdl examples/scientific/geophysical_demo.xdl

# Enable verbose logging
RUST_LOG=debug xdl examples/scientific/geophysical_demo.xdl

Performance issues

  • Reduce volume size (nx, ny, nz)
  • Use lower opacity in visualization
  • Close other GPU-intensive applications

Colormap errors

Use valid colormap names:

  • RAINBOW, VIRIDIS, PLASMA, INFERNO, TURBO, GRAYSCALE

References

Author

Generated with XDL - Extended Data Language