Rock Physics

Seismic Methods
By OgbonLab

From grains and fluids to velocity: choose the model, bound the answer, calibrate it to the rock.

The physics that links rocks to seismic: elastic bounds, fluid properties, Gassmann substitution, granular and inclusion models, and calibration to a real well, ending in a Rock Physics Lab where you compose a rock and predict its velocities.

13 parts 70 sections Free, browser-native
Start reading → First up: Why Rock Physics? The Missing Link

Table of contents

Every section is a working session: text, math, code, interactive widgets. Click any title to jump in.

Part 0: Part 0: The Bridge

  1. Why Rock Physics? The Missing Link
  2. Velocity Is a Model
  3. The Rock Physics of a Reflection
  4. Scales and Frequencies
  5. The Toolkit Map

Part 1: Part 1: Elasticity and the Moduli

  1. Stress, Strain, and Hooke's Law
  2. The Moduli That Matter
  3. From Moduli to Velocities
  4. Poisson's Ratio and Vp/Vs
  5. The Minerals

Part 2: Part 2: Bounds and Mixtures

  1. The Mixing Problem
  2. Voigt and Reuss
  3. The Hill Average
  4. Hashin-Shtrikman
  5. Bounds as Diagnostics
  6. Critical Porosity

Part 3: Part 3: The Fluids

  1. Why the Fluid Matters
  2. Brine
  3. Oil
  4. Gas
  5. Mixing Fluids
  6. Patchy Saturation

Part 4: Part 4: Gassmann and Fluid Substitution

  1. The Gassmann Idea
  2. The Workflow
  3. What Moves and What Doesn't
  4. Sensitivity
  5. When Gassmann Fails
  6. Fluid Substitution on Ogbon-1

Part 5: Part 5: Granular Rocks and Contact Models

  1. A Rock as a Grain Pack
  2. Hertz-Mindlin
  3. The Soft-Sand Line
  4. The Stiff-Sand Line
  5. Contact Cement
  6. Cement or Sorting

Part 6: Part 6: Inclusion Models

  1. Pores as Inclusions
  2. Kuster-Toksoz
  3. The Differential Effective Medium
  4. The Self-Consistent Medium
  5. The Xu-White Model
  6. Carbonate Pore Types

Part 7: Part 7: Calibration, From Data to Model

  1. Empirical Backbones
  2. Vs From Vp
  3. Density Without a Log
  4. Calibrating to Ogbon-1
  5. The Rock Physics Template
  6. Screening With the Template

Part 8: Part 8: Pressure, Stress, and Time-Lapse

  1. Effective Pressure
  2. Velocity and Pressure
  3. Detecting Overpressure
  4. Pressure or Fluid?
  5. Stress and Anisotropy
  6. Will the 4D Signal Show?

Part 9: Part 9: Layers, Shales, and Frequency

  1. The Layered Earth
  2. Backus Averaging
  3. Why Shales Are Anisotropic
  4. Velocity Dispersion
  5. Attenuation and Q
  6. Reconciling Lab, Log, and Seismic

Part 10: Part 10: Capstones, Fit for Rock

  1. Is the Bright Spot Gas?
  2. The Cemented Sand That Isn't Pay
  3. The Carbonate Porosity Paradox
  4. Overpressure or Gas?
  5. Watching CO₂

Part 11: Part 11: Review and Final Exam

  1. Review Question Bank
  2. Final Examination

Part 12: Part 12: The Rock Physics Lab

  1. The Lab
  2. The Model Reference Card
  3. Python Presets
  4. From the Lab to Research
  5. Which Model? An Advisor

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