Seismic · Exploration
Seismic Reflections
Part of the seismic energy bounces back to surface at each boundary between rock layers with different acoustic impedance.
What it does
The recorded two way time is converted to depth with a time depth relation built from velocity. Traces are arranged in 2D lines or in a 3D grid of bins that interpreters use to map traps.
Basics
| Cause | Acoustic impedance contrast |
| Measured | Two way travel time |
| 2D | Source and receivers in a line |
| 3D | Receiver lines with shots across them, data in bins |
Common failures
- Wrong time depth relation, which puts the target at the wrong depth
Troubleshooting
- Symptom
- Well finds the target deeper or shallower than mapped
- Likely cause
- Velocity error
- What to check
- Tie the seismic to the well with a synthetic from the sonic log and update velocities