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 Dimatec’s
extended length reaming shells are available for most wireline
core barrel assemblies in the ‘AWL’ (Ø
48,0 mm) to ‘PWL’ (Ø 122,6 mm) size range.
Their purpose is to assist in minimizing the degree of drill
hole angular deviation in target or deep hole drilling situations.
Stabilized reaming shells are available in two styles.
The first is a “Long-Ring” type with a 254mm
(10 inch) overall length that features a single extended
length diamond set matrix body gauge ring. The second is
a “Stabilized” type with a 467mm (18-3/8 inch)
overall length that features three matrix body gauge rings.
The lower (leading) gauge ring on the “Stabilized”
type is diamond set while the middle and upper gauge rings
are simply set with tungsten-carbide.
In all cases, the matrix body gauge rings
are cast onto the steel tool body. In terms of design, the
gauge rings are similar to the “Heavy
Duty” type in that the lower gauge ring includes
a tapered leading edge for ease of movement down the drill
hole. Wide spiral waterway canals are moulded into the gauge
rings. The setting on gauge ring of the “Long-Ring”
reaming shell and on the lower gauge ring of the “Stabilized”
reaming shell has the same density as that of the “Heavy
Duty” type and as such is designed to provide
the longest possible life. The gauge ring setting materials
are a combination of mechanically rounded natural drill
diamond in the size range of 20 to 35 stones per carat,
mesh-size synthetic diamond and seismic grade tungsten-carbide
wear pads. This setting is cast into a tough, abrasion resistant
matrix body. While the 254mm “Long-Ring” reaming
shells are designed to accept a standard inner tube stabilizer
ring, the 467mm (three ring) “Stabilized” reaming
shells may be supplied with either a recess for a standard
inner tube stabilizer ring OR an integral inner tube stabilizer
that is built-in to the body of the tool, depending on the
customer’s preference.
The Dimatec “Long-Ring” and “Stabilized”
reaming shells are suitable for use in all formation conditions
ranging from broken and abrasive to consolidated and non-abrasive.
As most stabilized reaming shells are physically longer
than the standard “D-Series”
and “Heavy Duty”
versions, it is necessary to use an appropriate inner tube
extension in order to compensate for the difference in overall
reaming shell length.
Optional setting is also available where the
natural mined diamond is replaced with synthetic materials
and is intended for use on drilling projects where potential
contamination by natural diamond crystals is objectionable.
 Tungsten-carbide
reaming shells do not include any form of diamond setting
and are used in applications where drilling depths are
limited to the overburden layer and there is no penetration
into the bedrock. This type of reaming shell is commonly
used in conjunction with tungsten-carbide set core bits.
Instead of a diamond set gauge ring, these
tools have hard-metal strips fused to the outside diameter
of the tool body. These hard-metal strips are composed
of micron sized tungsten-carbide particles that are
suspended in a metal alloy and are applied by means
of a plasma spray apparatus. These strips are then mechanically
ground to the appropriate set
diameter.
 Reaming
shell substitutes are steel adapters that are used in
place of a reaming shell where the stabilization of
the core barrel assembly is not required. They are manufactured
to the same physical dimensions as a diamond set reaming
shell of the corresponding size but do not include any
form of a gauge ring.
 Reaming
shell field gauges are used at a drill site to measure
the minimum permissible set diameter of the tool. Working
reaming shells that fully pass through a field gauge
should be taken out of service to prevent the possibility
of an undersized drill hole. These field gauges are
manufactured from hardened tool steel with a ground
gauging surface and are available for most standard
sizes of reaming shells.
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