MANUAL – REFLEX EZ-TRAC™ | 76
Figure 92 Landing collar box type
Landing collar box type
1. Thread the pin end of the landing collar into the box end of the
aluminium extension rod and tighten with pipe wrenches.
2. Thread the box end of the landing collar onto the overshot
assembly and tighten with pipe wrenches.
11.2 Surveying methods
The survey system may be run into and recollected from the borehole
using one of the surveying methods below.
11.2.1 Through drill string - wireline
Surveying with wireline through the drill string is most commonly used
for Single Shot surveys. This method allows surveying to be
performed without interrupting the drilling activity.
The instrument is run down the drill string, through the drill bit and into
the open hole. A landing collar is needed to prevent the survey
system from passing out of the drill string completely. There has to be
an opening at the drill bit, large enough for the instrument to pass
through, but small enough for the landing collar to stop.
When surveying with wireline through the drill string, gravity is used to
lower the instrument down the hole. Hence, the method is best suited
for inclined boreholes, with inclinations up to 45 degrees from vertical.
The survey system for surveying with wireline through the drill string
consists of the
REFLEX EZ-TRAC™ instrument, three aluminium
extension rods and a landing collar. This configuration allows the
instrument to extend 4.5 m/15 ft past the drill string, to avoid any
magnetic interference that the string may cause.
Through drill string - wireline
1. Before lowering the survey system down the drill string, ensure
that the drill rods are raised from the bottom a minimum of seven
meters.
2. With the survey system – including a landing collar of appropriate
size – attached to the overshot assembly, raise the system up the
drill slide.
3. Slowly lower the survey system down the drill string.
4. When the survey system reaches the bit, the landing collar will
rest in the bit – with the instrument extending 4.5 m/15 ft past the
bit – and the wireline should become slack.
5. Keep the survey system stationary at the survey station until the
measurement has been taken.
6. Using the wireline, slowly raise the survey system until it reaches
the collar of the hole.
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