Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TOP DRIVE APPARATUS
This invention relates to a top drive apparatus and
a method for transferring fluid from a rotor of a top
drive apparatus to a non-rotating conduit, such as a
gooseneck.
A top drive system for drilling wellbores, such as
oil and gas wells, is one of two common types of system,
the other being a rotary table system. A top drive system
generally comprises a main body which houses a motor for
rotating a sub which has a rotor connected to a sub
connectable to a single, stand or string of tubulars. The
tubulars may be any of: drill pipe, casing, liner,
premium tubular or any other such tubular used in the
construction, maintenance and repair of wellbores, such
as oil and gas wells. A top drive system is generally
arranged on a substantially vertical track on a derrick
of a rig. The top drive system is lifted and lowered on
the track with a line over a crown block on a travelling
block connected to the top drive system. The line is
reeled in and let out using a winch commonly known as a
drawworks. The top drive system can thus be used to trip
tubulars in and out of the wellbore; turn the drill
string to facilitate drilling the wellbore; and turn a
single or stand of tubulars in relation to a string of
tubulars hung in the wellbore to threadedly connect or
disconnect tubulars from a string of tubulars in the
drill string to length or shorten the string of tubulars.
An elevator generally depends on links attached to the
top drive to facilitate handling of tubulars and
alignment with the sub for connection and disconnection
therewith. A top drive system may also be used in
conjunction with a passive or active spider and/or with
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rotary tongs to facilitate connection and disconnection
of tubulars from the string of tubulars. A casing running
tool can be used to allow a top drive to connect a joint
of casing to a string of casing held in a spider in the
floor of a drilling rig. The casing running tool may have
external slips or internal slips to allow the joint of
casing to be gripped and rotated by the top drive
relative to the static casing string held in the spider.
The casing running tool may comprise a fluid connection
so that circulation of drilling mud can continue whilst
the joint of casing, once connected to the string, can be
lowered into the well. The casing running tool may also
comprise a blow out preventer for inhibiting a blow out
during tripping of the casing string.
Drilling fluids are transmitted to drilling swivels,
used in rotary table systems and top drive drilling
apparatus through a high-pressure swivel apparatus known
as a"washpipe" with a seal known as a"washpipe packing"
assembly. This packing assembly consists of a tubular
component which is held stationary, and through which the
drilling fluid flows under high pressure. A rotating
seal assembly of contact lip seals is mechanically fixed
to and rotates with the main shaft of the top drive or
swivel, and forms a dynamic seal against the outer
surface of the tubular washpipe as the main shaft rotates
while drilling. Due to the high pressures and surface
speeds involved in this arrangement, service life of the
washpipe packing is limited. Drilling fluid leaks are
therefore common on many drilling rigs, causing
contamination and damage to associated components and
environmental disruption.
The prior art discloses a variety of top drive
apparatus; for example, and not by way of limitation, the
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following U.S. Patents present exemplary top drive
apparatus and sealing assemblies: 4,458,768; 4,807,890;
4,984,641; 5,433,279; 6,276,450; 4,813,493; 6,705,405;
4,800,968; 4,878,546; 4,872,577; 4,753,300; 6,007,105;
6,536,520; 6,679,333; 6,923,254.
In top drives and rotary drilling the wash pipe
typically sealingly engages a set of circumferential
seals contained within a seal housing. Often, the wash
pipe remains stationary while the seals and the seal
housing rotate. Such seal assemblies have conventionally
included a series of reinforced, elastomeric, chevron
type seals interspersed with a series of reinforcing back
up rings. In certain prior art apparatus, one seal is
exposed to full hydraulic pressure on one side, and
atmospheric pressure on the opposite side. Full
differential pressure of the drilling mud acts on one
seal until that seal fails and the next seal in the
assembly then acts as the primary seal. Some prior art
swivel designs have sought to compensate for potential
run out and offset problems by allowing the wash pipe and
the seal housing to articulate.
According to the present invention, there is
provided a top drive apparatus for wellbore operations,
the top drive apparatus comprising a rotor with a bore
for the passage of fluid therethrough, drive apparatus
for rotating the rotor at a working speed, and a non-
rotating conduit in fluid communication with the rotor
characterised in that the top drive apparatus further
comprises a speed reducer apparatus connected between the
rotor and the conduit, a seal arranged between the rotor
and the speed reducer apparatus and a further seal
arranged between the speed reducer apparatus and the
conduit. The seal may be any known seal, including
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dynamic seals, rubber seals, elastomeric seals, seals
with one fin or a plurality of fins, or metal to metal
seals.
Preferably, the speed reducer apparatus comprises a
wash pipe, the seal arranged between the rotor and the
wash pipe and a further seal arranged between the wash
pipe and the conduit.
Advantageously, the speed reducer apparatus further
comprises a gear system. Preferably, the gear system
comprises a planetary gear system. Advanta geously, the
planetary gear system comprises a primary gear wheel
substantially concentric with the wash pipe and may be
fixed to the rotor or rotationally fixed to the rotor.
Preferably, the planetary gear system comprises at least
one satellite gear wheel which meshes with the primary
gear wheel. Advantageously, the at least one satellite
gear wheel rotates a secondary gear wheel rotationally
fixed to the wash pipe. Preferably, the wash pipe
comprise splines to mesh with a gear of the gear system.
Advantageously, the seal is arranged in a seal holder.
Preferably, the seal holder is fixed to the rotor.
Advantageously, the seal is rotationally fixed in the
seal holder. Alternatively, the seal is allowed rotate
within the seal holder. Preferably, the further seal is
arranged in a further seal holder. Advantageously, the
further seal holder is fixed to the conduit. Preferably,
the further seal is rotationally fixed in the seal
holder. Alternatively, the seal is allowed rotate within
the seal holder.
Preferably, the conduit comprises a gooseneck
(12,102), which may be rigid or flexible. The conduit can
comprise a straight piece of rigid pipe or flexible hose.
Preferably, the speed reducer apparatus reduces the
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rotational speed to at least 25% less than the rotor
rotational speed. Advantageously, the speed reducer
apparatus reduces the rotational speed to about 50% of
the rotor rotational speed.
Preferably, the speed reducer apparatus has a ring
housing, and a torque arrester. Preferably, the ring
housing allows rotation of the washpipe and the gear
system within the ring housing, advantageously on
bearings. Preferably, the torque arrester is in a fixed
relation to the conduit, and preferably, fixed to the
further seal holder. Advantageously, the torque arrester
comprises a bar. Preferably, the bar is substantially
parallel to the washpipe.
The present invention also provides a method for
transferring fluid from a rotor of a top drive apparatus
to a non-rotating conduit, the rotor rotating at a
working speed, characterised in that a seal is arranged
between said rotor and a speed reducer apparatus and a
further seal arranged between the speed reducer apparatus
and the non-rotating conduit, the method comprising the
step of the speed reducer apparatus rotating at a speed
slower than the working speed, such that the seal and
further seal each rotate at slower speed than the working
speed.
The present invention, in certain aspects, provides
a shaft sealing assembly in which an auxiliary shaft
rotated by a rotating main shaft is connected to and
rotates with the shaft via a speed reducer, for example,
a gear drive apparatus, between the main shaft and the
auxiliary shaft so that the auxiliary shaft rotates at a
reduced speed compared to the speed of the main shaft,
for example about one-half the main shaft speed, thus
exposing seals dynamically sealing against the auxiliary
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shaft to a surface which is moving at the reduced speed,
thus enhancing seal life.
In one particular aspect the main shaft is the main
drive shaft of a top drive used in wellbore operations,
for example drilling operations, and the auxiliary shaft
is in fluid communication with a washpipe through which
drilling fluid or mud flows to and through the top drive
apparatus.
The present invention discloses, in certain
embodiments, a top drive apparatus with a drive motor; a
drive quill or main shaft; a gear apparatus coupled to
the drive motor; a top drive support apparatus for
supporting various items; and a washpipe shaft in
accordance with the present invention connected with the
top drive main shaft via a speed reducer for rotation at
a speed less than that of the main shaft to enhance the
life of seal assemblies, for example with packings used
to seal against the washpipe shaft.
Accordingly, the present invention includes features
and advantages which are believed to enable it to advance
top drive shaft sealing technology. Characteristics and
advantages of the present invention described above and
additional features and benefits will be readily apparent
to those skilled in the art upon consideration of the
following detailed description of preferred embodiments
and referring to the accompanying drawings.
The present inventors have recognized the problems
associated with the rotation of a shaft with respect to
packing or seals and have realized that effective
reduction of the speed of shaft rotation can enhance seal
life and reduce seal wear.
By reducing the surface speed at which the seals
effectively operate, the present invention extends the
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service life of washpipe packing. Instead of the packing
rotating at main shaft speed against a stationary
washpipe, the present invention provides a speed reducing
mechanism (for example, a gear drive apparatus) which
rotates a washpipe shaft at, for example, one-half the
speed of the main shaft, thus the washpipe packing is not
subjected to the full speed of the main shaft. In one
embodiment of the present invention, a similar dynamic
sealing assembly is, optionally, added at the upper,
formerly stationary, end of the washpipe. By rotating
the washpipe shaft with the main shaft, but at a lower
speed than the main shaft, for example at one-half main
shaft speed, the or each of the sealing assemblies are
only subjected to one-half the original surface speed
(thus one half the original contact with a rotating
surface), increasing the overall service life of the
packing and washpipe assembly. Rotation of the washpipe
shaft is driven by the main shaft through a speed
reducing mechanism.
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For a better understanding of the present invention,
reference will now be made, by way of example, to the
accompanying drawings, in which:
Figure 1 is a schematic view of a prior art drilling
rig comprising a top drive drilling apparatus;
Figure 2 is a front view of a top drive apparatus
comprising a washpipe apparatus in accordance with the
present invention;
Figure 3 is a cross-section view of part of the
apparatus shown in Figure 2;
Figure 4 is a cross-section of part of the apparatus
shown in Figure 2;
Figure 4A is a schematic side cross-section view of
part of the apparatus in accordance with the present
invention; and
Figure 5 is an enlarged cross-section view of part
of the part shown in Figure 4.
Figure 1 shows a typical prior art drilling rig with
a derrick DK supporting a top drive TD which rotates
drill pipe DP. The top drive TD is supported from a
travelling block TB beneath a crown block CB. A
drawworks DS, on a rig floor RF raises and lowers the top
drive on a line L. The top drive moves on a guide track
GT.
Figure 2 shows a apparatus S in accordance with the
present invention with a top drive 1 with a drive motor
2; a gear apparatus 3 coupled to the top drive 1 with a
bearing support 4 and support links 4a; a washpipe
apparatus 10 with a washpipe shaft in accordance with the
present invention; an elevator load ring 5; a mud saver
apparatus 9; a lower internal blowout preventer 6; a
saver sub 7; a gooseneck 24; and a pipe gripper 8 with
supports 8A connected to the elevator load ring 5.
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As shown in Figure 3 a washpipe apparatus 10 in
accordance with the present invention has a main washpipe
body 12 disposed above and in fluid communication with a
main shaft M of the top drive apparatus S. A washpipe
shaft 70 projects into an upper packing assembly 16 and
rotates with the main shaft M (but is connected to the
main shaft only via a gear apparatus described below).
Upper and lower packing assemblies 16 and 18
respectively, have seals which seal against the washpipe
shaft 70.
Drilling mud flows through a channel 22 of the
gooseneck 24 into an interior 70a of the washpipe shaft
70 and from there down a channel C through the main shaft
M into the drill pipe.
Packing 15 of the upper packing assembly 16 does not
rotate with the washpipe shaft 70. The outer surface of
the washpipe shaft 70 rotates against the packing 15.
Preferably, the packing is in a rotationally fixed
relation to the gooseneck 24. The gooseneck 24 is
connected to gooseneck support 25 with bolts 26. For
assembly purposes a support 28 is connected to the upper
packing assembly 16 with a bolt (or bolts) 32 connected
to a housing 34. A bolt (or bolts) 36 connect the lower
packing assembly 18 adjacent the main shaft M. Following
assembly, the support 28 and the bolts 32, 36 may be
removed.
A primary gear 40 is secured to and rotates with the
main shaft within the housing 34. Teeth 40a on the
primary gear 40 mesh with teeth 42a on planetary gears 42
which are mounted on shafts 44 of a gear carrier 46.
Ball bearings 48 in a lower part 52 of the housing 34 and
ball bearings 49 under an upper part 54 of the housing 34
isolate the housing 34 from the rotation of the main
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shaft M, rotation of the primary gear 40, and rotation of
the planetary gears 42. A shield 62 shields items below
it from falling drilling mud and inhibits the leakage or
flow of mud from going into apparatuses below the shield
62, for example a top drive gear box.
Figures 4 and 5 show another embodiment of a
apparatus 100 in accordance with the present invention
useful as a washpipe apparatus in the apparatus S of
Figure 2. An s-pipe extension 101 is connected to a
gooseneck 102 (sometimes referred to as a washpipe
apparatus). Drilling mud flows through a channel lOla in
the s-pipe extension 101 into a channel 102a through the
gooseneck 102 down into a channel 121 of a washpipe shaft
120 and then to a channel 141 through a top drive shaft
140 driven by a top drive motor 105 (for example a
rotating shaft projecting from a top drive gear box 104
(shown in dotted line). A connector 103 with seals 103a,
103b, connects the s-pipe extension 101 to the gooseneck
102.
An upper seal carrier 106 connected too the
gooseneck 102 houses seal assemblies 107 (which include
seal carriers and seals) which seal against an outer
surface of the washpipe shaft 120. The upper seal holder
106 maintains the top of the washpipe shaft 120 in place.
A lower seal holder 108 connected to the shaft 140 houses
seal assemblies 109 (which include seal carriers and a
seal) which seal against an outer surface of the washpipe
shaft 120. The lower seal carrier 108 maintains the
bottom of the washpipe shaft 120 in place.
A speed reducer 160 interconnected between the shaft
140 and the washpipe shaft 120 reduces the speed of the
washpipe shaft 120 as compared to the speed of the shaft
140. Thus the seals 107 and 109 seal against a shaft
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(the washpipe shaft 120) rather than against the lower
shaft (the top drive shaft 140) and the seals are,
therefore, subjected to a shaft surface rotating at a
speed less than (for example, in certain aspects, at
least 25% less than, and, in other aspects about 50% less
than) the speed of the lower shaft.
Ports 106p and 108p house bolts 106b, 108b,
respectively, which maintain the seal assemblies 107,
respectively, in place. Bolts 102b bolt the gooseneck to
other structure. A torque arrester 112 is connected to
the washpipe, for example to the upper seal holder 106
and to the speed reducer 160. This torque arrester 112
prevents the ring housing 164 of the speed reducer 160
from rotating with other parts of the speed reducer 160.
The ring housing 164 provides a housing for bearings and
gears of the speed reducer 160. A splash shield 114 is
connected to the shaft 140.
A sun gear 162 is connected to the lower seal holder
108 and rotates with the shaft 140. Planetary gears 166
(for example, but not limited to, four planetary gears)
mounted on shafts 167 to a planetary gear carrier 168
mesh with and are driven by the sun gear 162. Splines
169 on the planetary gear carrier 168 mesh with
corresponding splines 128 on the washpipe shaft 120 to
rotatively drive the washpipe shaft 120.
The ring housing 164 houses a bearing assembly 170
with bearings 172 between the ring housing 164 and the
sun gear 162. The ring housing 164 houses a bearing
assembly 174 with bearings 176 between the ring gear and
the planetary gear carrier 168. The sun gear and the
planetary gears are sized, designed and configured to
achieve a desired gear reduction to reduce the speed of
the shaft 120 as compared to the speed of the shaft 140.
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For example, in one particular aspect, the gears are
designed so that the shaft 140 rotates twice as fast as
the shaft 120. In certain prior apparatuss seals (like
the seals 109) were subjected to a shaft (like the shaft
140) rotating at its operational speed and seals (like
the seals 107) were held stationary. The seals (like two
seals 107; and the seals 109) in apparatuss in accordance
with the present invention are now subjected to a shaft
rotating at a much lower speed.
Figure 4A shows schematically a apparatus 200 in
accordance with the present invention in which a washpipe
shaft 202 connected to a washpipe 204 is interconnected
via a speed reduction device 206 to a rotatable top drive
shaft 208. Seals 211, 212 seal against the washpipe
shaft 202. Both seals are subjected to a surface of the
washpipe shaft 202 against which they seal that is
rotating at a speed less than the rotational speed of the
top drive shaft 208. The seals 211 are in a seal holder
218 connected to the washpipe 204. Although the seals
212 are connected to a lower seal holder 214 that is
connected to the top drive shaft 208, the seals 212 only
"see" a surface speed of the washpipe shaft 202 which is
less than that of the top drive shaft 208 since the
washpipe shaft 202 and the top drive shaft 208 are
rotating in the same direction. The speed reduction
device 206 may be any suitable speed reducer, including,
but not limited to, a gear apparatus.
The present invention, therefore, provides in at
least certain embodiments, a top drive apparatus for
wellbore operations, the top drive apparatus having: a
main shaft with a main shaft channel therethrough; drive
apparatus for rotating the main shaft at a main shaft
speed; a speed reducer apparatus connected to the main
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shaft; a washpipe shaft connected to the speed reducer
apparatus so that the washpipe shaft is rotatable by the
speed reducer apparatus at a washpipe shaft speed less
than the main shaft speed; the washpipe shaft having a
top end and a bottom end, and a washpipe shaft channel
therethrough; a washpipe having a washpipe channel
therethrough, the washpipe shaft channel in fluid
communication with the washpipe channel; the washpipe
shaft channel in fluid communication with the main shaft
channel; a first seal holder connected to the washpipe
and holding first seal assemblies for sealing against the
top end of the washpipe shaft; and a second seal holder
connected to the main shaft and holding second seal
assemblies for sealing against the second end of the
washpipe. Such a apparatus may have one or some, in any
possible combination, of the following: the speed reducer
apparatus reducing the washpipe shaft speed to at least
25% less than the main shaft speed; the speed reducer
apparatus reducing the washpipe shaft speed to about 50%
of the main shaft speed; the speed reducer apparatus is a
gear apparatus including first gear apparatus connected
to the main shaft and second gear apparatus connected to
the washpipe shaft, the first gear apparatus for driving
the second gear apparatus; the first gear apparatus
includes a first gear, the second gear apparatus includes
a plurality of second gears, and the first gear drives
the plurality of second gears to rotate the washpipe
shaft; the speed reducer apparatus having a ring housing,
and a torque arrester connected to the ring housing and
to the washpipe; wherein the torque arrester is connected
to the first seal holder which is connected to the
washpipe; and/or wherein the drive apparatus includes a
top drive motor and a top drive gear apparatus driven by
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the top drive motor.
The present invention, therefore, provides in at
least certain embodiments, a top drive apparatus for
wellbore operations, the top drive apparatus having: a
main shaft with a main shaft channel therethrough; drive
apparatus for rotating the main shaft at a main shaft
speed; a speed reducer apparatus connected to the main
shaft; a washpipe shaft connected to the speed reducer
apparatus so that the washpipe shaft is rotatable by the
speed reducer apparatus at a washpipe shaft speed less
than the main shaft speed; the washpipe shaft having a
top end and a bottom end, and a washpipe shaft channel
therethrough; a washpipe having a washpipe channel
therethrough, the washpipe shaft channel in fluid
communication with the washpipe channel; the washpipe
shaft channel in fluid communication with the main shaft
channel; a first seal holder connected to the washpipe
and holding first seal assemblies for sealing against the
top end of the washpipe shaft; a second seal holder
connected to the main shaft and holding second seal
assemblies for sealing against the second end of the
washpipe; the speed reducer apparatus reduces the
washpipe shaft speed to about 50% of the main shaft
speed; the speed reducer apparatus is a gear apparatus
including first gear apparatus connected to the main
shaft and second gear apparatus connected to the washpipe
shaft; the first gear apparatus for driving the second
gear apparatus; and the drive apparatus includes a top
drive motor and a top drive gear apparatus driven by the
top drive motor.
The present invention, therefore, provides in at
least certain embodiments, a method for dynamically
sealing a drive shaft of a top drive apparatus, the top
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drive apparatus suitable for wellbore operations, the
method including: rotating a washpipe shaft of a top
drive apparatus; sealing against a top end and a bottom
end of the washpipe shaft, the washpipe shaft being part
of the top drive apparatus, the top drive apparatus
having a main shaft with a main shaft channel
therethrough, drive apparatus for rotating the main shaft
at a main shaft speed, a speed reducer apparatus
connected to the main shaft, a washpipe shaft connected
to the speed reducer apparatus so that the washpipe shaft
is rotatable by the speed reducer apparatus at a washpipe
shaft speed less than the main shaft speed, the washpipe
shaft having a top end and a bottom end, and a washpipe
shaft channel therethrough, a washpipe having a washpipe
channel therethrough, the washpipe shaft channel in fluid
communication with the washpipe channel, the washpipe
shaft channel in fluid communication with the main shaft
channel, a first seal holder connected to the washpipe
and holding first seal assemblies for dynamically sealing
against the top end of the washpipe shaft, a second seal
holder connected to the main shaft and holding second
seal assemblies for dynamically sealing against the
second end of the washpipe, and rotating the washpipe
shaft at a speed less than the speed of the main shaft;
wherein the washpipe shaft speed is at least 25% less
than the main shaft speed; wherein the washpipe shaft
speed is about 50% of the main shaft speed; wherein the
speed reducer apparatus is a gear apparatus including
first gear apparatus connected to the main shaft and
second gear apparatus connected to the washpipe shaft,
and the first gear apparatus for driving the second gear
apparatus, the method further including: driving the
second gear apparatus with the first gear apparatus;
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wherein the first gear apparatus includes a first gear,
the second gear apparatus includes a plurality of second
gears, and the first gear is for driving the plurality of
second gears to rotate the washpipe shaft, the method
further including: driving the plurality of second gears
with the first gear to rotate the washpipe apparatus;
wherein the speed reducer apparatus has a ring housing,
and a torque arrester connected to the ring housing and
to the washpipe; wherein the drive apparatus includes a
top drive motor and a top drive gear apparatus driven by
the top drive motor, the method further including driving
the top drive gear apparatus with the top drive motor,
and driving the main shaft with the top drive gear
apparatus.
The present invention, therefore, provides in at
least certain embodiments, a top drive shaft apparatus
including: a main shaft with a main shaft channel
therethrough; drive apparatus for rotating the main shaft
at a main shaft speed; a speed reducer apparatus
connected to the main shaft; a washpipe shaft connected
to the speed reducer so that the washpipe shaft is
rotatable by the speed reducer apparatus at a washpipe
shaft speed less than the main shaft speed; the washpipe
shaft having a top end and a bottom end, and a washpipe
shaft channel therethrough; a washpipe having a washpipe
channel therethrough, the washpipe shaft channel in fluid
communication with the washpipe channel; and the washpipe
shaft channel in fluid communication with the main shaft
channel. Such a apparatus may have one or some, in any
possible combination, of the following: a first seal
holder connected to the washpipe and holding first seal
assemblies for sealing against the top end of the
washpipe shaft, and a second seal holder connected to the
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main shaft and holding second seal assemblies for sealing
against the second end of the washpipe; wherein the speed
reducer apparatus reduces the washpipe shaft speed to at
least 25% less than the main shaft speed; and/or wherein
the speed reducer apparatus reduces the washpipe shaft
speed to about 50% of the main shaft speed; and/or the
speed reducer apparatus having a ring housing, and a
torque arrester connected to the ring housing and to the
washpipe.
The present invention, therefore, provides in at
least certain embodiments, a drive shaft apparatus
including: a main shaft with a main shaft channel
therethrough; drive apparatus for rotating the main shaft
at a main shaft speed; a speed reducer apparatus
connected to the main shaft; a secondary shaft connected
to the speed reducer apparatus so that the secondary
shaft is rotatable by the speed reducer apparatus at a
secondary shaft speed less than the main shaft speed; the
secondary shaft having a top end and a bottom end, and a
secondary shaft channel therethrough; a pipe having a
pipe channel therethrough, the secondary shaft channel in
fluid communication with the pipe channel; the secondary
shaft channel in fluid communication with the main shaft
channel; first sealing apparatus for sealingly contacting
the secondary shaft for sealing a main-shaft secondary-
shaft interface; and second sealing apparatus for
sealingly contacting a secondary-shaft-pipe interface.
In this document, the word "comprising" is used in
its non-limiting sense to mean that items following the
word are including, but items not specifically mentioned
are not excluded. A reference to an element by the
indefinite article "a" does not exclude the possibility
that more than one of the element is present, unless the
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context clearly requires that there be one and only one
of the elements.
