Depth Conversion Calculator

Convert between seismic two-way time (TWT) and depth using various velocity models. Supports constant velocity, interval velocity (Vint), and RMS velocity (Vrms) workflows. Essential for interpretation, well ties, and depth mapping.

Time-Depth Velocity Seismic Interpretation Well Ties

Input Parameters

Conversion Direction

Velocity Model

m/s
Typical water: 1500 m/s, sediments: 2000-3500 m/s

Input Time

ms

Results

Theory & References

Time-Depth Conversion

Depth = (TWT × Vavg) / 2

TWT = (2 × Depth) / Vavg

Key Concepts:

  • TWT: Two-Way Time (seismic reflection time)
  • OWT: One-Way Time = TWT / 2
  • Vavg: Average velocity from surface to depth
  • Vint: Interval velocity within a layer

Velocity Models

Constant Velocity:

Simple model with single velocity. Good for quick estimates or thin sections.

Interval Velocity (Vint):

Layer-cake model with different velocities per layer. Most realistic for stratified geology.

Depth = Σ (Δti × Vint,i) / 2

RMS Velocity (Vrms):

Root-mean-square velocity from NMO analysis. Common in processing.

Vrms = √[Σ(Vint,i² × Δti) / Σ Δti]

Dix Equation

Convert RMS to interval velocity:

Vint = √[(tnVrms,n² - tn-1Vrms,n-1²) / (tn - tn-1)]

Used to derive interval velocities from stacking velocities.