Thank you for your post.
You could create a calculation field that searches for "Log #" and if exists, grab everything that follows the "#" character. Assuming your field is entitled "Tape Number", create a calculation field, CALC, with the formula:
If ( PatternCount ( Tape Number ; "Log #" ) > 0 ; Right ( Tape Number ; Length ( Tape Number ) - Position ( Tape Number ; "Log #" ; 1 ; 1 ) - 4 ) ; "" )
You could also put this in a script and place the result in another field.
If you need clarification for any of the above functions, let me know.