MANUAL – REFLEX EZ-TRAC™ | 79
11.2.3 In front of drill string
Surveying with the instrument pushed in front of the drill string is most
commonly used for Multi Shot surveys. With this method it is possible
to survey both in and out of the borehole, which allows for
repeatability and averaging of survey results.
Using an adapter, the survey system is attached to the drill string.
The survey system is pushed in front of the drill string as it is being
run into the hole.
To recollect the instrument, the drill string has to be tripped out. The
survey system will come with the drill string as it is being removed
from the hole.
The survey system for surveying in front of the drill string consists of
the
REFLEX EZ-TRAC™ instrument, a minimum of three aluminium
extension rods and an adapter.
Do not rotate the drill string counter-clockwise when advancing the
survey system into or out of the borehole. In that case, the survey
system might be un-threaded.
In front of drill string
1. Thread the adapter into the box end of the aluminium extension
rod and tighten with pipe wrenches.
2. Gently place the survey system in the collar of the hole. Be
careful to secure the survey system to prevent it from falling into
the hole.
3. Thread the survey system onto the drill string. Tighten with pipe
wrenches.
4. Slowly move the survey system forward to the first survey station.
5. Keep the survey system stationary at the survey station until the
measurement has been taken.
6. Continue adding drill rods to advance to next survey station and
repeat the measuring process.
7. Repeat step 5 and 6 until the last station is measured or the
bottom of the hole is reached. Caution, always stop short of
bottom depth to prevent damaging of the survey system - the
system extends 4.5 m/15 ft beyond the drill string, and build up of
sledge and loose material can be located at the bottom.
8. Begin removing the rods. If surveying out of hole is required,
remove the correct amount of rods until the next survey station
has been reached.
9. Keep the survey system stationary at the survey station until the
measurement has been taken.
10. Continue removing rods and repeat step 8 and 9 until the adapter
reaches the collar of the hole.
11. Gently lift the survey system from the hole.
12. Place the survey system in a safe position away from the
borehole and unthread the running gear.
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