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Surveys Using an Overshot in Normal Core
Retrieval
A Pajari Quik-Connect
coupling is installed between your cable swivel or spearhead at the top of
the overshot.
The e-SYNC
has the same Quik-Connect
couplings that you just installed on
your overshot. When it
is time to take a survey, you simply insert the e-SYNC
and make it part of your overshot.
This now allows the e-SYNC
to take a survey, the same time as you retrieve your core barrel. The
Quik-Connect set-up also allows
you to easily remove the e-SYNC when
you just want to use your normal overshot.
This "Steep Hole" assembly,
is capable of surveying holes from vertical (-90º) to -35º. Lowering to the core barrel is achieved by using gravity.
In flat holes and up holes a standard pump-in
overshot would be required.
The threads on the e-SYNC
are an internal
1"
- 16 TPI thread making the cable swivel/spearhead collar standard with Q and O designated wireline
overshots.
Retrieving
The Core
Normal drilling practices can be followed to retrieve the core with only two procedural cautions.
When lowering the instrument in steep holes (- 90º to -50º), lower it as rapidly as it will naturally fall then gently slow it down to 30% of the lowering speed for the last 30-40 meters. This will protect the instrument from unnecessary shock.
In shallow holes (-50º to -35º), it is not necessary to slow the overshot down as slowing down may result in failure to retrieve the core barrel assembly.
Once the instrument has reached the core barrel, allow the cable to stay slack and leave the instrument to lock undisturbed for
20 seconds. After the locking time is complete, raise the core barrel as rapidly as you would normally until the overshot reaches the top of the drill rods.
On retrieval the e-SYNC
is ready to download the survey results as soon as it clears the collar.
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