The starting point for subsurface depth measurements.
The most popular
Logging Reference Points
are:
Rig Floor
( in
Open Hole Logging
applications )
Tubing Head
( in
Cased-Hole Logging
applications )
Rotary Table
( in drilling applications)
Kelly Bushing
Sea Level
( in
geodetic
applications)
Ground Level
( in
geodetic
applications
)