Topic:
Are there any 'helpful hints' when defining a drift curve?

Description:
        

Solution:
Defining the drift curve is the second most important influence (after correctly 
edited logs) on the quality of the final synthetic.  While it is possible to 
edit checkshot data, most companies treat checkshots as data to be interpreted 
not edited.  The geophysically correct treatment is to accept the checkshot data 
and interpret it to define a drift curve.  The drift curve is used to adjust the 
overall time-depth relationship of the sonic log to that of the checkshot data, 
but keeping all of the high-frequency data within the log data.

With this in mind, some rules of thumb for defining a drift curve are:

1.)  Use as few points as possible.
2.)  Honor all of the checkshot data within the accuracy of the checkshots
    (typically, +/- 2 msec).
3.)  If a single checkshot really doesn't seem to fit, ignore it.



Last Modified on: 10-FEB-99