U.S. patent application number 14/766576 was filed with the patent office on 2015-12-31 for dual bearing rotating control head and method.
The applicant listed for this patent is SMITH INTERNATIONAL, INC.. Invention is credited to Jason Philip Lock.
Application Number | 20150376972 14/766576 |
Document ID | / |
Family ID | 51300280 |
Filed Date | 2015-12-31 |
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United States Patent
Application |
20150376972 |
Kind Code |
A1 |
Lock; Jason Philip |
December 31, 2015 |
DUAL BEARING ROTATING CONTROL HEAD AND METHOD
Abstract
An apparatus comprises a first bearing assembly, a second
bearing assembly, a housing and a pipe. The first bearing assembly,
the second bearing assembly and the housing define an interior
space. The pipe extends through the first bearing assembly and the
second bearing assembly and through the interior space.
Inventors: |
Lock; Jason Philip; (Red
Deer, Alberta, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SMITH INTERNATIONAL, INC. |
Houston |
TX |
US |
|
|
Family ID: |
51300280 |
Appl. No.: |
14/766576 |
Filed: |
February 11, 2014 |
PCT Filed: |
February 11, 2014 |
PCT NO: |
PCT/US2014/015709 |
371 Date: |
August 7, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61762989 |
Feb 11, 2013 |
|
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Current U.S.
Class: |
166/250.08 ;
166/381; 166/84.3 |
Current CPC
Class: |
E21B 33/085 20130101;
E21B 19/00 20130101; E21B 33/06 20130101; E21B 21/08 20130101; E21B
47/06 20130101 |
International
Class: |
E21B 33/06 20060101
E21B033/06; E21B 21/08 20060101 E21B021/08; E21B 47/06 20060101
E21B047/06; E21B 19/00 20060101 E21B019/00 |
Claims
1. An apparatus comprising: a first bearing assembly; a second
bearing assembly; a housing, the first bearing assembly, the second
bearing assembly and the housing defining an interior space, and a
pipe extending through the first bearing assembly and the second
bearing assembly and through the interior space.
2. The apparatus of claim 1, wherein the housing comprises at least
one port in fluid communication with the interior space.
3. The apparatus of claim 2, further comprising a main pressure
sensor in fluid communication with the interior space.
4. The apparatus of claim 2, further comprising a fluid pump in
fluid communication with the interior space.
5. The apparatus of claim 4, further comprising a pressure
regulator in fluid communication with the interior space.
6. The apparatus of claim 5, wherein the fluid pump moves a
lubricant.
7. The apparatus of claim 1, further comprising a first pressure
sensor located exteriorly of the interior space functionally
adjacent the first bearing assembly.
8. The apparatus of claim 1, further comprising a second pressure
sensor exteriorly of the interior space adjacent the second bearing
assembly.
9. The apparatus of claim 1, wherein each of the first bearing
assembly and the second bearing assembly comprises a stripper
element, the pipe to be accommodated by the stripper elements.
10. The apparatus of claim 1, wherein the apparatus comprises a
rotating control head.
11. A method comprising: pressurizing fluid to a predetermined
value in an interior space defined by a housing, a first bearing
assembly and a second bearing assembly; and measuring a pressure of
the interior space to determine a leak in at least one of the first
bearing assembly and the second bearing assembly when the measured
pressure differs from the predetermined by a predetermined
amount.
12. The method of claim 11, further comprising measuring a pressure
from a first pressure sensor located exteriorly of the interior
space and adjacent the first bearing assembly to determine a leak
in the first bearing assembly.
13. The method of claim 11, further comprising measuring a pressure
from a second pressure sensor located exteriorly of the interior
space and adjacent the second bearing assembly to determine a leak
in the second bearing assembly.
14. The method of claim 11, wherein the fluid comprises a
lubricant.
15. The method of claim 11, further comprising replacing at least
one of the first bearing assembly and the second bearing
assembly.
16. A method comprising: pumping lubricant into an interior space
of an apparatus defined by at least a first bearing assembly and a
second bearing assembly, each of the first bearing assembly and the
second bearing assembly comprising a stripper element; and
inserting a pipe through the interior space so as to go through the
first bearing assembly and the second bearing assembly.
17. The method of claim 16, further comprising moving the pipe with
respect to the interior space so as to lubricate at least one
stripper element.
18. The method of claim 17, wherein moving the pipe in a first
direction introduces the lubricant to the stripper element
associated with the first bearing assembly.
19. The method of claim 17, wherein moving the pipe in a second
direction introduces the lubricant to the stripper element
associated with the second bearing assembly.
20. The method of claim 17, wherein the pumping generates a
pressure substantially equal to a pressure in an annular space in a
wellbore.
Description
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0001] Not applicable.
BACKGROUND
[0002] This disclosure relates generally to the field of wellbore
pressure control devices. More specifically, the disclosure relates
to pressure control devices that control and diver drilling and
wellbore fluids while providing a seal around a tubular
component.
[0003] Wellbore pressure control devices include devices known as
rotating control heads, rotating diverters, rotating blowout
preventers (hereinafter rotating control head or "RCH"). Such
pressure control devices are configured to enable a string of pipe
and/or wellbore drilling or intervention tools to sealingly pass
therethrough axially, and further to enable rotation of the pipe
while sealing the wellbore hydraulically. When used, for example in
wellbore drilling operations, a drill pipe string is passed through
a bearing assembly in the RCH. The bearing assembly enables a seal
element therein and the pipe to rotate relative to a housing that
may be affixed to the top of a casing or other pipe disposed at
least partially into the wellbore. The housing is configured to
enable hydraulic communication to the interior of the wellbore
below the bearing assembly. One non-limiting use for RCHs may be in
managed pressure drilling.
[0004] When bearings in the bearing assembly fail, expensive and
difficult procedures to remove the pipe from the wellbore are
conducted while maintaining the wellbore hydraulic seal through the
RCH. Also, difficult and expensive pipe removal operations are
conducted because seal elements in the bearing assembly fail.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a schematic view of a pipe being inserted into a
wellbore through a rotating control head (RCH);
[0006] FIG. 2 is a first side view of an example RCH according to
the present disclosure;
[0007] FIG. 3 is a cut away view of the RCH shown in FIG. 1;
[0008] FIG. 4 is a second side view of the assembled RCH shown in
FIG. 3; and
[0009] FIG. 5 is a cut away view of the RCH shown in FIG. 4.
DETAILED DESCRIPTION
[0010] An example wellbore operation in which a rotating control
head (RCH) may be used is shown schematically in FIG. 1. A wellbore
12 may be drilled into subsurface Earth formations 13 to a selected
depth. A pipe 14, for example, a drill pipe or drill string may
include one or more structures 10, such as centralizers,
stabilizers or other drilling tools that have a diameter larger
than the nominal outer diameter (diameter) of the pipe 14. The pipe
14 may be lowered into the wellbore 12 by a hoisting system such as
a drilling rig 16 or the like. The drilling rig 16 may include a
drawworks 20 or similar hoisting apparatus that extends and
retracts a drill line 21. Movement of the drill line 21 cooperates
with sheaves or "blocks" 18 to cause upward and downward motion of
a top drive 22 or similar device to enable rotational motion of the
pipe 14.
[0011] Typically, during operations, the wellbore 12 is filled with
fluid 11, such a "drilling mud", a completion brine or other fluid
used to drill and/or complete the wellbore 12. The fluid 11 is
typically lifted from a pit or tank 26 disposed at the surface. The
tank 26 may include a supply of cleaned or conditioned fluid 28.
The fluid 28 may be lifted by a pump 24 which discharges the fluid
to the top drive 22. Internal rotating seal elements in the top
drive 22 enable the fluid 28 to be pumped through the interior of
the pipe 14 into the wellbore 12. The top drive 22 may also be used
to rotate the pipe 14, such as for axially lengthening (drilling)
the wellbore 12.
[0012] The wellbore 12 may include a pipe or casing 33 ("surface
casing") set to a relatively limited depth near the surface. An
upper end of the surface casing 33 may be coupled to a sealing
element called a rotating control head 34. The rotating control
head 34 may be coupled to the casing by a flange 34B to a
corresponding flange 33A at the upper end of the surface casing 33,
although the manner of coupling the rotating control head 34 to the
surface casing 33 is not a limitation on the scope of the present
disclosure.
[0013] The rotating control head 34 seals an annular space 12A
between the exterior of the pipe 14 and the interior of the surface
casing 33 to prevent uncontrolled release of fluid 11 from the
wellbore 12. The rotating control head 34 may include a fluid
discharge outlet 34A. The fluid discharge outlet 34A may be
disposed below sealing elements (FIGS. 2 and 3) in the rotating
control head 34 to enable flow of the fluid 11 out of the annular
space 12A. The fluid outlet 34A may be coupled through a
controllable choke 32 or similar variable restriction flow control
device that ultimately may return the fluid 11 to the tank 26. In
some examples, the fluid discharge outlet 34A may include a pump 30
coupled thereto at its discharge side so that fluid pressure in the
wellbore 12 outside the pipe 14 may be maintained at a selected
level. The pressure of fluid being discharged from the annular
space 12A may be measured using a pressure sensor 127C in fluid
communication with the fluid discharge outlet 34A.
[0014] The example shown in FIG. 1 has a pipe 14 in the form of a
drill string being inserted into the wellbore 12. It should be
clearly understood that the rotating control head 34 of the present
disclosure is equally applicable to any type of pipe being inserted
into a wellbore, including as non-limiting examples casing, liner,
coiled tubing, production tubing and rod strings. Accordingly, a
rotating control head according to the present disclosure is not
limited in scope to being used with a drill string. If the pipe 14
is a casing or liner, the structures 10 may be centralizers affixed
to the exterior of the pipe 14 to provide force to urge the pipe 14
toward the center of the wellbore 12 when inserted therein. A
possible advantage of the rotating control head 34 of the present
disclosure when structures are used on the pipe 14 having a larger
diameter than the nominal outer diameter of the pipe 14 will be
further explained below.
[0015] In an example dual bearing assembly rotating control head
according to the present disclosure, and as will be explained
further below, two independent bearing assemblies, each having a
sealing or stripper element associated therewith, may be assembled
to a rotating control head housing in tandem and connected to each
other in spaced apart relation by a housing such as a spacer spool.
A first bearing assembly may be configured to support most of the
operating load of wellbore operations. As the first bearing
assembly reaches the end of its operable life, whether by impending
failure of the bearing and/or the sealing element, a second bearing
assembly may enable continuing wellbore operations to a point where
the ordinary sequence of wellbore operations would allow for a
bearing assembly to be replaced without unduly interrupting
wellbore operations.
[0016] In the present example, and as will be further explained
below with reference to FIGS. 2 and 3, the bearing assemblies may
be connected to each other and longitudinally spaced apart by a
housing such as a "spacer spool" and clamping system. A first
bearing assembly 118 may bolt to or otherwise be affixed to the
bottom of the interior of a main rotating control head housing that
is affixable to the wellbore pipe or surface casing (33 in FIG. 1),
or, for example, to a drilling riser when the rotating control head
is used in marine drilling operations. A second bearing assembly
110 may be affixed in place on the upper end of the housing or
spacer spool using fasteners similar to those used in conventional
rotating control heads, for example, band-type clamps or threaded
rings. The entire dual bearing system may then clamp onto the main
rotating control head housing using, for example, a single band
type clamp or other type of fastener, e.g., mating flanges with an
internal o-ring seal. As will be further explained, the spacer
spool may have an interior space between the bearing assemblies
that is in fluid communication with a port in the spacer spool.
Such port may be used, for example, for measurement of pressure
and/or introduction of fluid into the interior space in the spacer
spool.
[0017] The first bearing assembly 118 as well as the second bearing
assembly 110 may require additional seals within a bearing pack,
sufficiently strong to control the intended maximum operating
pressures (e.g., 3000 pounds per square inch static) in the
wellbore (12 in FIG. 1). The bearing pack and associated seals will
be explained below with reference to FIG. 3. The spacer spool 114
may allow the first and second bearing assemblies 118, 110 to
operate independently. With suitably selected longitudinal spacing
between the first and second bearing assemblies 118, 110, such as
may be obtained by suitable selection of the length of the spacer
spool 114, the housing or spacer spool 114 may enable a
continuously engaged seal around at least part of a nominal outer
diameter portion of the pipe (e.g., 14 in FIG. 1) when
through-passing larger diameter pipe elements, such as casing
collars or drill pipe tool joints are used with such pipe (14 in
FIG. 1) thus limiting possible fluid bypass from the annular space
(12A in FIG. 1) when stripping operations (i.e., longitudinal
movements of the pipe 14 in FIG. 1) occur.
[0018] The example first and second bearing assemblies 118, 110 may
be stabbed onto a pipe (e.g., the pipe 14 in FIG. 1), positioned
within the rotating control head housing and the spacer spool 114,
respectively, retained in place and the interior space in the
spacer spool 114 between the two bearing assemblies 118, 110 may
subsequently be filled with a fluid medium, e.g., lubricant, and
pressurized to a predetermined pressure. Such pressure may be a
equal to or above anticipated operating pressures in the wellbore
(12 in FIG. 1) in some implementations. By measuring pressure
within the spacer spool 114, the wellbore operator may be able to
detect pressure anomalies both within the spacer spool 114 and the
bearing assemblies 118, 110. For example, a measured pressure spike
or loss within the spacer spool 114 may indicate first bearing
assembly 118 leakage or proximate failure. The foregoing may enable
the wellbore operator sufficient warning to allow determining a
timeline of the anticipated life expectancy of the second bearing
assembly 110, thus enabling the wellbore operator to plan a bearing
assembly change at a point within the wellbore operations that
minimizes disruption of the ordinary course of such operations.
[0019] A side view of an assembled dual bearing assembly rotating
control head 34 according to the present disclosure is shown in
FIG. 2. A second bearing assembly 110 may be retained in place
within an upper end of a second housing, hereinafter referred to as
a "spacer spool" 114 by a band clamp 112 or other retaining element
known in the art.
[0020] The spacer spool 114 may include one or more ports 114A,
terminated with couplings such as flanges or other pressure tight
coupling features. The one or more ports 114A may be in fluid
communication with an interior space (114B in FIG. 3) in the spacer
spool 114. The interior space 114B may enable fluid introduced
therein to contact both bearing assemblies 118, 110 (explained
further below). By providing one or more ports 114A, it may be
possible to measure pressure within the spacer spool 114, and/or to
pump fluids into the spacer spool 114. Measuring pressure may be
performed by having a main pressure sensor 127 in fluid
communication with one of the ports 114A. Measuring pressure using
the main pressure sensor 127 is functionally equivalent to
measuring pressure proximate the first bearing assembly 118 outside
the interior space (114B in FIG. 3). It may be possible, for
example, to pump fluid such as a lubricant (e.g., lubricating oil)
into the spacer spool 114 through the one or more ports 114A to
clean and lubricate, and thus possibly extend the operating
lifetime of a first bearing assembly (see 118 in FIG. 3) and/or the
second bearing assembly 110. In one example, a fluid pump 129 may
be in fluid communication with the one or more ports 114A to enable
such pumping. The pressure applied by the pump 129 may be
maintained at any selected value by a pressure regulator 127A
coupled to either of the ports 114A. In another example, the pump
129 may be used to pump fluid into the interior of the spacer
spool, e.g., through one of the ports 114A so that the rotating
control head (34 in FIG. 1) may be tested for any leakage. Such
pressure testing may require insertion of a pipe (e.g., 14 in FIG.
1) through the first and second bearing assemblies (110 and 118,
respectively, in FIG. 3) to close a passage (explained below)
provided through the first and second bearing assemblies.
[0021] The first bearing assembly (118 in FIG. 3) may be retained
in place in a main rotating control head housing 124 using a
flange-type bearing retainer 123. The flange type bearing retainer
123 may be affixed to a first housing, hereinafter referred to as
the "main rotating control head housing" 124 using a band clamp 120
or any other coupling device. The flange type bearing retainer 123
may be coupled to a mating flange 121 on the spacer spool 114 using
studs and nuts, shown generally at 125, such studs and nuts being
of types known in the art for affixing mating flanges in a flange
coupling together.
[0022] The main rotating control head housing 124 may couple to the
wellbore pipe or casing (33 in FIG. 1) using a fluid pressure tight
connector of any type known in the art, for example a flange 34B as
shown in FIG. 2. The example flange 34B shown in FIG. 2 is not
intended to limit the scope of what may be used to couple the main
rotating control head housing 124 to the wellbore pipe (33 in FIG.
1).
[0023] The fluid discharge port 34A explained with reference to
FIG. 1 is shown in FIG. 2 in a convenient position in the main
rotating control head housing 124. The use of band clamps as shown
in FIG. 2 is not intended to limit the scope of means by which the
main rotating control head housing 124 and the first bearing
assembly (118 in FIG. 3) are respectively coupled. Likewise, using
a band type clamp 112 to couple the second bearing assembly 110 to
the spacer spool 114 is only provided as an example and is not
intended to limit the means by which the second bearing assembly
110 may be affixed to the spacer spool 114.
[0024] Some of the details of the first and second bearing
assemblies will now be explained with reference to FIGS. 3-5. FIG.
4 shows a view of the rotating control head shown in FIG. 2 rotated
90 degrees. The view of FIG. 4 more clearly shows the one or more
ports 114A in the spacer spool. In the example shown in FIG. 4, the
main rotating control head housing 124 may include an additional
fluid discharge port 34B, which is in hydraulic communication with
the interior of the main rotating control head housing 124. FIG. 5
shows a cross-sectional view of the view shown in FIG. 4. The ports
114A are visible as being in fluid communication with the interior
of the spacer spool 114. The two fluid discharge ports 34A, 34B in
the main rotating control head housing 124 are also observable as
being in fluid communication with the interior of the main rotating
control head housing 124 below the first stripper element (122 in
FIG. 3).
[0025] Each of the first 118 and second bearing 110 and assemblies
may include a respective stripper element 122, 116 to provide
sealing engagement to a pipe or pipe string moved longitudinally
through each bearing assembly 118, 110, respectively, e.g., the
pipe 14 as shown in FIG. 1. With reference to the second bearing
assembly 110, such assembly may include a sleeve 110A for engaging
and/or guiding the pipe (14 in FIG. 1) as it is moved
longitudinally through the second bearing assembly 110. The
stripper element 116 may be affixed to a lower end of the sleeve
110A so that pipe moved through the sleeve 110A has a pressure
tight seal to substantially prevent escape of fluid from within the
interior space 114B in the spacer spool 114.
[0026] The sleeve 110A may include a shoulder 110F on an exterior
thereof. The shoulder 110F may be in contact with an upper bearing
110C and a lower bearing 110D each on one side of the shoulder
110F. The upper bearing 110C and the lower bearing 110D may
rotatably transfer axial loading from the sleeve 110A to a bearing
housing 110E. The bearing housing 110E may be the portion of the
second bearing assembly that is coupled to the spacer spool 114.
The upper bearing 110C and the lower bearing 110D may each be
sealed with respective seals 111 of any type known in the art to
seal a rotating shaft passing through a bearing supporting such
shaft rotatably in a fixed housing.
[0027] The first bearing assembly 118 may be mounted in the main
rotating control head housing 124 as explained above, and may have
substantially the same components, including a sleeve and stripper
element 122 as explained with reference to the second bearing
assembly 110.
[0028] An additional pressure sensor 127B may be disposed in a
chamber therefor located above the upper seal 111. In the event any
fluid leaks past the second bearing assembly 110, suck leakage may
be detected by an increase in the pressure measured by the
additional pressure sensor 127B. By using measurements of pressure
from the pressure sensor (127 in FIG. 2) in communication with one
of the ports (114A in FIG. 2) and the additional pressure sensor
127A, it may be possible to identify which of the first and second
bearing assemblies and associated stripper elements may be
leaking.
[0029] As explained above, by having at least one port (114A in
FIG. 2) in fluid communication with an interior 114B of the spacer
spool 114, it may be possible to measure pressure inside the spacer
spool 114. Thus, indications of any fluid leakage from the wellbore
(12 in FIG. 1) through the first bearing assembly 118 and/or the
second 110 bearing assembly may be observed. In one example, if the
measured pressure inside the spacer spool 114 deviates from a
setpoint or predetermined pressure (such as may be applied by the
pump 129 in FIG. 2) by a predetermined amount, an indication of
leakage in the first bearing assembly and/or its associated
stripper element may be inferred. In one example, depending on a
pressure in the wellbore (12 in FIG. 1), an increase in measured
pressure in the spacer spool 114 may indicate the stripper element
122 in the first bearing assembly 118 is leaking. In another
example, a reduction in pressure measured in the spacer spool 114
may indicate that the striper element 116 in the second bearing
assembly 110 is leaking. In addition, measurements of pressure
using the additional pressure sensor may indicate leakage of the
seal and bearing pack associated with the second bearing assembly
110.
[0030] One or more of such indications based on measured pressure
may provide the wellbore operator an indication that the first
bearing assembly requires removal and replacement. In some
examples, such removal and replacement may be performed at a time
during wellbore operations so as to minimize disruption of such
operations. One specific example may be during a time in which the
entire pipe is removed from the wellbore to change a drill bit.
During the time in which wellbore operations continue even with
failure of the stripper element 122 in the first bearing assembly
118, the stripper element 116 in the second bearing assembly 110
may prevent fluid from bypassing the rotating control head 34, thus
providing the wellbore operator with a possible opportunity to
continue wellbore operations uninterrupted until a convenient time
is available for bearing assembly replacement. The foregoing
continuation of wellbore operations may be based on an estimated
remaining lifetime of the second bearing assembly and/or the
stripper element associated therewith. Provided that the estimated
remaining lifetime is at least or exceeds an expected time until
the convenient time, wellbore operations may continue until the
convenient time, whereupon the first and/or second bearing
assemblies may be replaced.
[0031] Having two bearing assemblies as described above with
reference to FIGS. 2 and 3 may also enhance safety of wellbore
operations by reducing the possibility of fluid leakage past the
rotating control head 34 as a result of having redundant bearing
assemblies.
[0032] As previously explained, it may also possible to use the one
or more ports (114A in FIG. 2) in the spacer spool 114 to pump
lubricant, such as oil, into the space (114B in FIG. 3) between the
first and second bearing assemblies to clean and lubricate the
stripper elements (116 and 118 in FIG. 3), thus prolonging their
lifetime. For example, when the pipe (14 in FIG. 1) is moved
downwardly, lubricant on the exterior of the pipe may be moved into
the interior of the first stripper element (122 in FIG. 3). When
the pipe is move upwardly, lubricant may be moved into the interior
of the second stripper element (118 in FIG. 3). Such lubrication
may substantially increase the useful life of the stripper elements
(116, 118 in FIG. 3).
[0033] Another example may be to pump fluid, e.g., lubricant, into
the interior of the spacer spool (114B in FIG. 3) to a pressure
substantially equal to the expected operating pressure in the
wellbore casing (33 in FIG. 1). By pumping fluid into the interior
space (114B in FIG. 3) to such pressure, it may be possible to
avoid sudden introduction of wellbore pressure to the second
bearing assembly (110 in FIG. 3) and stripper element (116 in FIG.
3) in the event of failure of the first bearing assembly seals
and/or the associated stripper element (118 in FIG. 3). By
preventing such sudden introduction of pressure to the second
bearing assembly, the possibility of consequent failure of the
second bearing assembly and/or the associated stripper element may
be reduced.
[0034] A rotating control head that includes two independent and
sealed bearing assemblies and sealing elements may provide
increased safety in wellbore operations and reduced risk of
wellbore fluid leakage and consequent environmental hazard.
[0035] In one example, an apparatus comprises a first bearing
assembly, a second bearing assembly, a housing and a pipe. The
first bearing assembly, the second bearing assembly and the housing
define an interior space. The pipe extends through the first
bearing assembly and the second bearing assembly and through the
interior space.
[0036] In another example, a method comprises pressurizing fluid to
a predetermined value in an interior space defined by a housing, a
first bearing assembly and a second bearing assembly. The method
further comprises measuring a pressure of the interior space to
determine a leak in at least one of the first bearing assembly and
the second bearing assembly when the measured pressure differs from
the predetermined by a predetermined amount.
[0037] In yet another example, a method comprises pumping lubricant
into an interior space of an apparatus defined by at least a first
bearing assembly and a second bearing assembly. Each of the first
bearing assembly and the second bearing assembly comprises a
stripper element. The method further comprises inserting a pipe
through the interior space so as to go through the first bearing
assembly and the second bearing assembly.
[0038] Although the preceding description has been described herein
with reference to particular means, materials and embodiments, it
is not intended to be limited to the particulars disclosed herein.
Rather, it extends to all functionally equivalent structures,
methods and uses, such as are within the scope of the appended
claims.
* * * * *