Time-Depth Dix Calculator

Convert RMS velocities to interval velocities using the Dix equation, then perform accurate time-to-depth conversion. Input velocity picks from seismic velocity analysis and generate depth-converted horizons with detailed velocity profiles.

Dix Equation Interval Velocity Time-Depth Velocity Analysis

Velocity Picks

Time-Vrms Pairs

Data Import/Export

CSV format: time(ms), vrms(m/s)

Results

Theory & References

Dix Equation

The Dix equation converts RMS (stacking) velocities to interval velocities:

Vint(n) = √[(Vrms(n)² × tn - Vrms(n-1)² × tn-1) / (tn - tn-1)]

Key Points:

  • Converts velocity analysis picks to layer velocities
  • Assumes horizontal layers (Dix, 1955)
  • Sensitive to Vrms picking errors
  • May give unrealistic values in complex geology

RMS Velocity (Vrms)

Root-mean-square velocity from NMO velocity analysis:

Vrms = √[Σ(Vint,i² × Δti) / Σ Δti]

Characteristics:

  • Obtained from semblance or velocity spectrum
  • Best-fit hyperbolic moveout velocity
  • Always ≥ average velocity
  • Smoothly increasing with time for normal geology

Time-to-Depth Conversion

Once interval velocities are known:

Depthn = Σ(Vint,i × Δti / 2)

Workflow:

  1. Pick Vrms at key horizons from velocity analysis
  2. Apply Dix equation to calculate Vint for each interval
  3. Integrate Vint to get depth for each horizon
  4. Build time-depth relationship for volume conversion