Note: Descriptions are shown in the official language in which they were submitted.
CA 02203091 1997-04-18
INTEGRAL PUMPING TEE BLOWOUT PREVENTER AND TUBING ROTATOR
TECHNICAL FIELD
The present invention relates to an apparatus for attachment to a
wellhead. More specifically, the invention relates to an assembly of wellhead
equipment comprising a flow or pumping tee, a blowout preventer and a tubing
rotator, wherein the flow tee, the blowout preventer and the tubing rotator
are
combined and permanently connected to form a single, integral apparatus.
BACKGROUND ART
A typical wellhead is often comprised of a pumping tee or flow tee
connection, a blowout preventer and a tubing rotator. These individual
components
are typically joined to each other and to the wellhead by way of temporary
connections
between two of the components or between one of the components and the
wellhead.
The tubing rotator is typically mounted to the wellhead adjacent the upper end
of the
casing string at the ground surface by bolting a flanged surface on the lower
end of the
tubing rotator to a flanged surface on the wellhead. The blowout preventer is
then
typically mounted on top of the tubing rotator by bolting together flanged
surfaces on
the upper end of the tubing rotator and the lower end of the blowout preventer
respectively, and the flow tee is then typically mounted on top of the blowout
preventer by bolting together flanged surfaces on the upper end of the blowout
preventer and the lower end of the flow tee respectively. The remainder of the
wellhead structure is then typically mounted on top of the flow tee by being
bolted to a
flanged surface on the upper end of the flow tee. Other forms of temporary
connections amongst the wellhead and the individual components are also
possible.
These connections are designed to be temporary in order to facilitate the
dismantling
of all or a portion of the wellhead structure for the purpose of servicing the
well.
Tubing rotators are used in the industry to suspend and rotate the tubing
string within the wellbore. By rotating the tubing string, typical wear
occurring within
the internal surface of the tubing string, by either a reciprocating or
rotating rod string,
is distributed over the entire internal surface. As a result, the tubing
rotator may
prolong the life of the tubing string. Further, the constant movement of the
inner
surface of the tubing string relative to the rod string may inhibit or reduce
buildup of
wax and other materials within the tubing string.
CA 02203091 1997-04-18
The pumping tee or flow tee provides a connection between one or more
production flow lines and the wellhead such that the wellbore fluid may be
directed
through the wellhead and into the production flow lines. The blowout preventer
provides a mechanism for sealing off the production tubing about the rod
string
within the wellhead. In particular, the blowout preventer provides means for
sealing
off the annulus between the rod string and the production tubing in order to
inhibit
the release of pressure or fluid from the wellbore through the wellhead.
The combined use of a conventional flow tee, blowout preventer and
tubing rotator connected in series on a wellhead results in the wellhead
having
multiple connections and significant height. It has been found that excessive
wellhead
height may cause weakening and instability of the wellhead and present
servicing
difficulties. The temporary connections between the components may also
contribute
to this weakening and instability. Canadian Patent Application No. 2,153,612
describes
an "Integral Blowout Preventer and Flow Tee" combining the functions of a flow
tee
and a blowout preventer in a single apparatus, thus reducing the number of
temporary
connections and the overall height of the wellhead, but does not contemplate
combining the functions of a flow tee, a blowout preventer and a tubing
rotator in a
single apparatus, which provides even fewer temporary connections and the
possibility of even more sturdiness, stability and further reduced wellhead
height.
There is therefore a need in the industry for an apparatus which provides
for the functions of a flow tee, blowout preventer and tubing rotator in an
integral
unit. Specifically, there is a need for an apparatus which combines the
functional
elements of the flow tee, the blowout preventer and the tubing rotator in a
single
apparatus which is sturdier and more stable in comparison with a flow tee,
blowout
preventer and tubing rotator as separate or individual units mounted together.
There
is also a need in the industry for such an integral apparatus that will still
facilitate
servicing of the well.
DISCLOSURE OF INVENTION
The present invention combines the functions of a flow tee, a blowout
preventer and a tubing rotator in a single integral apparatus, thus reducing
the
number of temporary connections that must be made to a wellhead in comparison
with a flow tee, blowout preventer and tubing rotator which are mounted on a
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CA 02203091 1997-04-18
wellhead separately. This reduced number of temporary connections in turn may
result in a more sturdy and stable wellhead, and may also result in reduced
overall
wellhead height.
In one aspect, the present invention presents an improvement in an
assembly of wellhead equipment comprising a flow tee having an upper end and a
lower end, a blowout preventer having an upper end and a lower end and a
tubing
rotator, for suspending and rotating a tubing string contained within a
wellbore,
having an upper end and a lower end, and wherein the lower end of the flow tee
is
connectable to the upper end of the blowout preventer and the lower end of the
blowout preventer is connectable to the upper end of the tubing rotator,
wherein the
improvement comprises combining the flow tee, the blowout preventer and the
tubing rotator in a single apparatus so that the lower end of the flow tee is
permanently connected to the upper end of the blowout preventer and the lower
end
of the blowout preventer is permanently connected to the upper end of the
tubing
rotator.
By combining the flow tee, the blowout preventer and the tubing rotator
in a single apparatus, the temporary connection between the lower end of the
flow tee
and the upper end of the blowout preventer and the temporary connection
between
the lower end of the blowout preventer and the upper end of the tubing rotator
can be
eliminated. Preferably, the overall height of the apparatus is less than that
of a flow
tee, blowout preventer and tubing rotator when mounted separately on a
wellhead.
This reduced height may be realized by eliminating connecting flanges between
the
flow tee and the blowout preventer and eliminating connecting flanges between
the
blowout preventer and the tubing rotator.
In a preferred embodiment of the invention, the apparatus comprises a
housing having an upper end, an upper section, a middle section, a lower
section, a
lower end and a fluid path extending therethrough between the upper and lower
ends
and wherein the flow tee is comprised of the upper section of the housing, the
blowout
preventer is comprised of the middle section of the housing and the tubing
rotator is
comprised of the lower section of the housing. Preferably, the upper, middle
and
lower sections of the housing comprise a continuous housing which is
integrally
formed as one piece, but the housing may be comprised of several pieces
permanently
connected together, such as by welding.
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Preferably, the apparatus has a lower end and an upper end, and further
comprises temporary connection means located at the upper and lower ends of
the
apparatus which may be comprised of any means which are compatible with the
wellhead and with other wellhead equipment. Where the apparatus comprises a
housing, these temporary connection means comprise respectively means for
connecting the upper end of the housing to other wellhead equipment and means
for
mounting the lower end of the housing on a wellhead. The upper end connecting
means may be comprised of the housing, which housing may comprise an upper
surface on the upper end of the housing or a connecting flange located at the
upper
end of the housing. The mounting means may be comprised of the housing, which
housing may comprise a lower surface on the lower end of the housing, a
mounting
flange located at the lower end of the housing, or a base plate connected to
the lower
end of the housing.
The tubing rotator may be further comprised of a supported member for
connecting to the tubing string and a supporting structure for rotatably
supporting the
supported member so that the tubing string is rotatably supported within the
wellbore.
Any combination of supported member and supporting structure which performs
this
basic function may be used in the invention. Preferably, however, the
supporting
structure engages the wellhead, and may comprise a support flange for mounting
on
the wellhead, or may comprise the lower section of the housing, including the
base
plate in circumstances where the housing comprises a base plate. In
circumstances
where the wellhead is comprised of a casing bowl having a tapered inner
surface, the
supporting structure may include a tapered outer surface which is compatible
with the
inner surface of the casing bowl.
As can be seen, the servicing of wells which include the apparatus of the
present invention may be simplified, in that the apparatus can be removed from
and
installed upon the wellhead as one unit, rather than as three separate
components, as
is the case where the flow tee, blowout preventer and tubing rotator are not
combined
in one integral apparatus. In addition, in the preferred embodiment of the
invention,
the apparatus may be removed from the wellhead to facilitate servicing without
compromising the safety of the well, since the tubing string can remain
anchored in
the wellbore while most of the apparatus is removed and is replaced with a
service
blowout preventer.
BRIEF DESCRIPTION OF DRAWINGS
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CA 02203091 1997-04-18
Embodiments of the invention will now be described with reference to
the accompanying drawings, in which:
Figure 1 is a side view of a wellhead having a reciprocating rod and
walking beam, in which the apparatus is mounted for operation;
Figure 2 is a side view of a wellhead having a rotating rod in which the
apparatus is mounted for operation;
Figure 3 is a top view of a preferred embodiment of the apparatus
connected to a gear box;
Figure 4 is a longitudinal sectional view of the preferred embodiment of
the apparatus taken along line 4-4 of Figure 3 showing a preferred embodiment
of the
tubing rotator;
Figure 5 is a longitudinal sectional view of the apparatus taken along line
5-5 of Figure 3;
Figure 6 is a longitudinal sectional view of the apparatus taken along line
6-6 of Figure 3 including a polished rod ram and a polished rod ram rubber
backer;
Figure 7 is a pictorial view of the polished rod ram shown in Figure 6;
Figure 8 is a pictorial view of the polished rod ram packer shown in
Figure 6;
Figure 9 is an outer end view of the polished rod ram shown in Figure 7;
Figure 10 is a cross-sectional view of the polished rod ram taken along
line 10-10 of Figure 9;
Figure 11 is a longitudinal sectional view a first alternate embodiment of
the apparatus taken along a line similar to that of Figure 4, showing a first
alternate
embodiment of the tubing rotator;
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Figure 12 is a longitudinal sectional view of a second alternate
embodiment of the apparatus taken along a line similar to that of Figure 4,
showing a
second alternate embodiment of the tubing rotator;
Figure 13 is a longitudinal sectional view of a third alternate embodiment
of the apparatus taken along a line similar to that of Figure 4, showing a
third alternate
embodiment of the tubing rotator;
Figure 14 is a top view of a drive ring shown in the tubing rotator of
Figures 12 and 13;
Figure 15 is a cross-sectional view of the drive ring taken along line 15-15
of Figure 14;
Figure 16 is a top view of a lower supported member shown in Figures 12
and 13; and
Figure 17 is a longitudinal sectional view of the lower supported member
taken along line 17-17 of Figure 16.
BEST MODE OF CARRYING OUT INVENTION
Referring to Figures 1 and 2, the within invention is directed at an
improvement of an assembly of wellhead equipment. A typical wellhead (20) is
comprised of plurality of components mounted at the ground surface above a
wellbore, including a wellhead flange (22) and wellhead equipment such as a
tubing
rotator for suspending and rotating a tubing string (24) contained within the
wellbore,
a blowout preventer, a flow tee or pumping tee and a rod stuffing box (26).
Typically,
the wellhead equipment is mounted above the wellhead flange (22).
Further, typically, a lower end of the tubing rotator is directly or
indirectly
mounted, or otherwise connected, to the wellhead flange (22). As well, the
upper end
of the tubing rotator is directly or indirectly mounted or connected to the
lower end of
the blowout preventer. The upper end of the blowout preventer is then mounted
or
connected to the lower end of the flow tee. Finally, the upper end of the flow
tee is
typically mounted or connected to the lower of the rod stuffing box (26). The
wellhead
equipment may be interconnected in this manner by any suitable means,
structure,
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CA 02203091 1997-04-18
apparatus or mechanism. However, typically, each of the flow tee, blowout
preventer
and tubing rotator includes a flange located at each of its upper and lower
ends. Thus,
the equipment is mounted together or interconnected by joining or fastening
the
adjacent flanges on the lower end of the flow tee and the upper end of the
blowout
preventer and by joining or fastening the adjacent flanges on the lower end of
the
blowout preventer and the upper end of the tubing rotator.
Further, a rod or rod string (28) is run through the wellhead (20) and into
the wellbore through a continuous fluid passage or pathway which extends
through
each of the flow tee, the blowout preventer and the tubing rotator. The well
may be
produced by a reciprocating rod (28), reciprocated by a pump jack or walking
beam at
the surface as shown in Figure 1. Alternately, the well may be produced by a
rotating
rod (28), driven by a rotary pump drive at the surface as shown in Figure 2.
In either
case, the upper end of the rod (28) includes a polished rod (30) that extends
through the
entire wellhead (20). The polished rod (30) provides a smooth sealable surface
between
the reciprocating or rotating rod (28) and the rod stuffing box (26) or the
rod blowout
preventer when it is closed or sealed against the polished rod (30). The upper
end of
the polished rod (30) is held by a rod clamp such that the rod (28) is
suspended in the
wellhead (20) and the wellbore. The rod clamp is supported either by the
walking
beam, as shown in Figure 1, or from a thrust bearing plate forming part of the
rotary
pump drive, as shown in Figure 2.
The wellbore of the well is typically completed by cementing a casing
string (32) in at least the upper portion of the wellbore. Typically, the
wellhead flange
(22) is comprised of a casing bowl (34), welded or screwed to the top of the
casing string
(32), having a flange at its uppermost surface. The casing bowl (34) may
include an
inwardly tapered inner surface (36).
The within invention is comprised of an improvement in the above
described wellhead equipment. In particular, the improvement is comprised of
combining the flow tee, blowout preventer and tubing rotator in a single,
integral or
continuous unit or apparatus (27). Thus, an apparatus (27) is provided which
combines the functions of each of these three components. The apparatus (27)
combines the flow tee, blowout preventer and tubing rotator, and is configured
or
arranged such that a lower end of the flow tee is permanently connected to, or
associated with, an upper end of the blowout preventer and a lower end of the
blowout
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CA 02203091 1997-04-18
preventer is permanently connected to, or associated with, an upper end of the
tubing
rotator.
The permanent connections between the flow tee, blowout preventer and
tubing rotator may be made by any means, method, process, device, mechanism or
apparatus suitable for permanently connecting or affixing together the
adjacent ends or
surfaces of the various components such that a single apparatus (27) is formed
therefrom. More particularly, connecting flanges, fastened together by bolts,
screws or
the like, or other interconnecting members, such as nipples and the like, are
not
located between the flow tee and the blowout preventer and between the blowout
preventer and the tubing rotator. For instance, the adjacent ends or surfaces
may be
welded together. However, in the preferred embodiment, the flow tee, blowout
preventer and tubing rotator are permanently connected together by casting,
machining or otherwise forming the components of the apparatus (27), being the
flow
tee, blowout preventer and tubing rotator, as a continuous or integral unit.
Specifically, in the preferred embodiment, the apparatus (27) is comprised of
a housing
(38) which is preferably cast, machined or otherwise formed as a continuous
unit or
piece. The flow tee, blowout preventer and tubing rotator are each comprised
of a
section of the housing (38) as described further below.
Referring to Figures 4 and 11-13, the apparatus (27) is comprised of a
housing (38) having an upper end (40), an opposing lower end (42), a
longitudinal axis
extending therebetween and an outer surface or wall (43). The housing (40) may
be of
any shape or configuration suitable for its intended function or purpose, as
described
herein. However, the housing (38) is preferably circular on cross-section, as
shown in
Figure 3, such that the circumference of the housing (38) defines the outer
wall (43).
A primary fluid passage (44) or pathway is defined by the apparatus (27)
and extends longitudinally therethrough such that the primary fluid passage
(44)
permits the wellbore fluids from the tubing string (24) to pass through the
apparatus
(27). The primary fluid passage (44) extends through the housing (38) between
the
upper and lower ends (40, 42) and is preferably aligned such that the primary
fluid
passage (44) is substantially parallel to the longitudinal axis of the housing
(38).
Further, a longitudinal axis of the primary fluid passage (44) is preferably
concurrent or
coincident with the longitudinal axis of the housing (38) such that the
primary fluid
passage (44) is substantially centrally located within the housing (38). In
operation, the
polished rod (30) passes through the apparatus (27) within the primary fluid
passage
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CA 02203091 1997-04-18
(44). The primary fluid passage (44) may be of any shape or size suitable for
its
intended function and which permits the reciprocation or rotation of the
polished rod
(30) therein. However, in the preferred embodiment, the primary fluid passage
(44) is
circular on cross-section in order to facilitate the passage of the wellbore
fluid
therethrough and to facilitate the movement of the polished rod (30) therein.
The upper end (40) of the housing (38) is preferably connectable to other
wellhead equipment by any fastening or connecting means, mechanism, structure
or
device suitable for temporarily fastening or connecting the apparatus (27) to
such other
wellhead equipment. Thus, further wellhead equipment may be mounted upon the
apparatus (27). In the preferred embodiment, the housing (38) further
comprises a
connecting flange (46) located at the upper end (40) of the housing (38) for
connecting
the apparatus (27) to the other wellhead equipment. As a result, the
connecting flange
(46) forms the uppermost surface of the apparatus (27).
In the preferred embodiment, the connecting flange (46) is integral or
continuous with the remainder or balance of the housing (38). Preferably, the
housing
(38) is cast, machined or otherwise formed such that the connecting flange
(46) is
incorporated into or comprises the housing (38). However, alternately, the
connecting
flange (46) may comprise a separate or distinct portion of the housing (38),
which is
connected to the upper end (40) of the housing (38) by any fastening or
connecting
means, device, apparatus or mechanism suitable for fastening or connecting the
adjacent surfaces of the connecting flange (46) and the housing (38). In this
instance,
the connection is preferably permanent, however, the connecting flange (46)
may be
removably attached or connected to the upper end (40) of the housing (38)
where
preferred or otherwise desirable to permit versatility or flexibility with
respect to the
specific wellhead equipment which may be mounted upon the connecting flange
(46).
As shown in Figures 3-5, in the preferred embodiment, the connecting
flange (46) is comprised of an upper surface (47) on the upper end (40) of the
housing
(38), which upper surface (47) is adapted for connection to the other wellhead
equipment. Any manner of adapting, or any structure, device or mechanism for
adapting, the upper surface (47) for connection to the other wellhead
equipment may
be used. However, in the preferred embodiment, the connecting flange (46) is
comprised of the upper surface (47) defining at least two apertures (48), and
preferably a
plurality of apertures (48), spaced circumferentially about the primary fluid
passage
(44). The apertures (48) are for receiving fasteners, such as bolts, screws or
the like,
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CA 02203091 1997-04-18
therein such that the other wellhead equipment may be fastened to the
connecting
flange (46). Thus, the arrangement or configuration of the apertures (48) must
be
compatible with the adjacent wellhead equipment to be mounted upon the
apparatus
(27), and in particular, must be compatible with a flange or lowermost surface
of such
equipment. Further, the upper surface (47) of the housing (38) comprising the
connecting flange (46) preferably defines an annular groove (50) about the
circumference of the primary fluid passage (44), for receiving an O-ring or
other seal,
for sealing between the adjacent surfaces of the connecting flange (46) and
the other
wellhead equipment.
Similarly, the lower end (42) of the housing (38) is preferably connectable
to the components of the wellhead, or wellhead equipment, which are located in
the
wellhead beneath the apparatus (27). Preferably, the lower end (42) of the
housing (38)
is directly connected to the wellhead flange (22). However, the lower end (42)
may be
indirectly connected to the wellhead flange (22) where other wellhead
equipment is
located between the apparatus (27) and the wellhead flange (22). Thus, in the
preferred
embodiment, the apparatus (27) is further comprised of means for mounting the
lower
end of the housing (38) on the wellhead (20), and preferably, on the wellhead
flange
(22). The lower end (42) may be connected to the wellhead flange (22) by any
fastening
or connecting means, mechanism, structure or device suitable for temporarily
fastening or connecting the lower end (42) of the housing (38) to the wellhead
(20). For
instance, the mounting means may be comprised of a mounting flange permanently
or temporarily connected at the lower end (42) of the housing (38).
. In the preferred embodiment, the mounting means is comprised of a
lower surface (51) on the lower end (42) of the housing (38), which lower
surface (51) is
adapted for connection to the wellhead, and preferably, the wellhead flange
(22).
However, as stated above, the lower surface (51) may be adapted for connection
to
further wellhead equipment located between the apparatus (27) and the wellhead
flange (22). Any manner of adapting, or any structure, device or mechanism for
adapting, the lower surface (51) for connection to the wellhead flange (22)
may be used.
However, in the preferred embodiment, the lower surface (51) defines at least
two
apertures (52), and preferably a plurality of apertures (52),
circumferentially spaced
about the lower surface (51). The apertures are for receiving fasteners (54),
such as
bolts, screws or the like, therein. The apertures (52) are arranged or
configured on the
lower surface (51) to be compatible with the wellhead flange (22). In the
preferred
embodiment, the fastener (54), being a stud bolt, is screwed into the
apertures (52) in
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the lower surface (51) of the housing (38). When the apparatus (27) is mounted
upon
the wellhead (20), the fasteners (54) extend from the apertures (52) in the
lower surface
(51) of the housing (38), through compatible apertures defined by the wellhead
flange
(22). A nut (56) is then screwed onto the end of the fastener (54) to secure
the housing
(38), and thus the apparatus (27), upon the wellhead flange (22).
In the preferred embodiment, the lower surface (51) of the housing (38) is
immediately adjacent or proximal to the wellhead flange (22) when the
apparatus (27)
is mounted thereon. In particular, the lower surface (51) is supported by the
upper
surface of the wellhead flange (22) and the lower surface (51) directly
engages the
wellhead flange (22). However, alternately, the lower surface of the housing
(38) may
be a spaced distance from the wellhead flange (22) such that the lower surface
(51) does
not directly engage the wellhead flange (22). For instance, one or more
further
elements or components of the apparatus (27) may be located between the lower
surface (51) and the wellhead flange (22). Thus, the lower surface (51) of the
housing
(38) engages the further element or elements and the further elements, in
turn, engage
the wellhead flange (22). In addition, depending upon the specific mounting
means of
the lower surface (51), and depending upon the specific manner of engagement
of the
lower surface (51) with the wellhead (20), the lower surface (51) of the
housing (38) may
include a seal for sealing the lower surface (51) to the adjacent surface of
the wellhead
flange (22) or other elements of the apparatus (27). For instance, the lower
surface (51)
may define an annular groove for receiving an O-ring or other sealing device.
Further, the housing (38) may be further comprised of a base plate (60)
connected to the lower end (42) of the housing (38) In this instance, the
mounting
means, for mounting the lower end (42) of the housing (38) on the wellhead
(20), is
comprised of the base plate (60), as shown in the Figures 11-13 of the first,
second and
third alternate embodiments of the apparatus (27) respectively. The housing
(38) is
connected or affixed to the base plate (60), and the base plate (60) is, in
turn, connected
to the wellhead by any fastening or connecting means, mechanism, structure or
device
suitable for temporarily fastening or connecting the base plate (60) to the
wellhead (20).
Preferably, in these alternate embodiments, the mounting means is particularly
comprised of the base plate (60) having an upper surface (61) for connection
or
attachment to the lower surface (51) of the housing (38) and a lower surface
(62)
adapted for connection to the wellhead, and preferably, the wellhead flange
(22). Thus,
the mounting means is particularly comprised of the lower surface (62) of the
base
plate (60). However, as stated above, the lower surface (62) may be adapted
for
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connection to further wellhead equipment located between the apparatus (27)
and the
wellhead flange (22).
Any manner of adapting, or any structure, device or mechanism for
adapting, the lower surface (62) for a temporary connection to the wellhead
flange (22)
may be used. However, preferably, the lower surface (62) defines at least two
apertures
(63), and preferably a plurality of apertures (63), circumferentially spaced
about the
lower surface (62). The apertures (63) are substantially identical to the
apertures (52), as
described above, in the lower surface (51) of the housing (38). The apertures
(63) are for
receiving the fasteners (54) therein. The apertures (63) are arranged or
configured on
the lower surface (62) to be compatible with the wellhead flange (22). In the
preferred
embodiment, the fastener (54) is screwed into the apertures (63) in the lower
surface
(62) of the base plate (60). When the apparatus (27) is mounted upon the
wellhead (20),
the fasteners (54) extend from the apertures (63) in the lower surface (62) of
the base
plate (60), through compatible apertures defined by the wellhead flange (22).
The nut
(56) is then screwed onto the end of the fastener (54) to secure the base
plate (60), and
thus the housing (38), upon the wellhead flange (22).
In the first and third alternate embodiments shown in Figures 11 and 13
respectively, the lower surface (62) of the base plate (60) is immediately
adjacent or
proximal to the wellhead flange (22) when the apparatus (27) is mounted
thereon. In
particular, the lower surface (62) is supported by the upper surface of the
wellhead
flange (22) and the lower surface (62) directly engages the wellhead flange
(22).
However, alternately, the lower surface (62) of the base plate (60) may be a
spaced
distance from the wellhead flange (22) such that the lower surface (62) does
not directly
engage the wellhead flange (22) as shown in Figure 12 of the second alternate
embodiment. In this alternate embodiment, one or more further elements or
components of the apparatus (27) may be located between the lower surface (62)
and
the wellhead flange (22). Thus, the lower surface (62) of the base plate (60)
engages the
further element or elements and the further elements, in turn, engage the
wellhead
flange (22).
In the alternate embodiments, depending upon the specific mounting
means of the lower surface (62), and depending upon the specific manner of
engagement of the lower surface (62) of the base plate (60) with the wellhead
(20), the
lower surface (62) of the base plate (60) preferably includes a seal for
sealing the lower
surface (62) to the adjacent surface of the wellhead flange (22) or other
elements of the
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CA 02203091 1997-04-18
apparatus (27). For instance, the lower surface (62) may define an annular
groove for
receiving an O-ring (58) or other sealing device therein.
In the alternate embodiments, as indicated above, the base plate (60) may
be permanently connected or affixed to the lower end (42) of the housing (38).
However, preferably, the base plate (60) is preferably removably connected or
affixed to
the lower end (42) of the housing (38). The base plate (60) may be removably
connected
br affixed by any means, mechanism or structure suitable for temporarily
connecting
the base plate (60) to the lower end (42) of the housing (38). However,
preferably, as
shown in Figures 11-13, the lower surface (51) of the housing (38) is
comprised of an
externally threaded extension (64) extending axially away from the housing
(38). The
extension (64) is received within an internally threaded recess (65) defined
by the upper
surface (61) of the base plate (60). One or more seals, as required, may be
located
between the lower surface (51) of the housing (38) and the adjacent upper
surface (61)
of the base plate (60) when the extension (64) is threaded into the recess
(65).
Although the housing (38) in the preferred embodiment of the apparatus
(27), as shown in Figure 4, is not comprised of the base plate (60). the use
of a
removable base plate (60) may be preferred in some circumstances.
Specifically, a
removable base plate (60) may be preferred where the apparatus (27) is
intended to be
mounted upon varying configurations or sizes of the wellhead flange (22). In
particular, as the diameter and configuration of the apertures for receiving
the
fasteners, or the bolt ring, in the wellhead flange (22) varies between
different
wellheads (20), the base plate (60) may be changed to suit, and be compatible
with, the
particular wellhead flange (22).
Further, in the preferred and alternate embodiments, the housing (38) is
preferably further comprised of an upper section (68), a lower section (70)
and a middle
section (72) located therebetween. Preferably, the flow tee of the apparatus
(27) is
comprised of the upper section (68) of the housing (38), the blowout preventer
of the
apparatus (27) is comprised of the middle section (72) of the housing (38) and
the
tubing rotator of the apparatus (27) is comprised of the lower section (70) of
the
housing (38). Preferably, the sections (68, 70, 72) are permanently connected
together by
any means, method, device, apparatus or mechanism suitable for permanently
connecting or fastening the adjacent surfaces of the sections (68, 70, 72) of
the housing
(38). For instance, the sections (68, 70, 72) of the housing (38) may be
permanently
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CA 02203091 1997-04-18
connected or joined together by welding the sections together at their points
of contact
with each other.
However, preferably, the upper, middle and lower sections (68, 72, 70) are
permanently connected together by casting, machining or otherwise forming the
housing (38) as a continuous, integral unit or single piece or component of
the
apparatus (27). Thus, in the preferred embodiment, the sections (68, 70, 72)
comprise a
continuous housing (38). As indicated above, the primary fluid passage (44)
extends
through the housing (38) through each of the upper, middle and lower sections
(68, 72,
70). Thus, preferably, the continuous housing (38) is comprised of the
connecting
flange (46), the upper section (68), the middle section (72) and the lower
section (70). In
the alternate embodiments, the base plate (60), which further comprises the
housing
(38), is then removably or temporarily connected to the lower surface (51) of
the
housing (38).
As indicated, the flow tee portion of the apparatus (27), or the portion of
the apparatus (27) performing the flow tee function, is comprised of the upper
section
(68) of the housing (38). Referring to Figures 3 and 5, the upper section (68)
of the
housing (38) defines a portion of the primary fluid passage (44) therein.
Further, the
upper section (68) defines at least one secondary fluid passage (76) having a
longitudinal axis intersecting, or extending transversely to, to the primary
fluid
passage (44) such that each secondary fluid passage (76) extends from the
primary fluid
passage (44) to the outer wall (43) of the housing (38) within the upper
section (68) of
the housing (38). As a result, the wellbore fluids are permitted to flow from
the tubing
string (24) through the primary fluid passage (44) in the apparatus (27) and
into, and
subsequently through, each secondary fluid passage (76). The end of each
secondary
fluid passage (76), when in use, is preferably connected to an external
production pipe
(78), as shown in Figures 1 and 2, which does not form part of the apparatus
(27).
Any feasible number of secondary fluid passages (76) which does not
unduly weaken the overall structure of the apparatus (27) may be defined by
the upper
section (68) of the housing (38). However, in the preferred embodiment, as
shown in
Figures 3 and 5, the upper section (68) defines two secondary fluid passages
(76). In this
case, the longitudinal axes of the two secondary fluid passages (76) are
aligned such that
the longitudinal axes are substantially concurrent or coincident with each
other and
the secondary fluid passages (76) exit the outer wall (43) of the housing (38)
at opposing
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CA 02203091 1997-04-18
sides of the housing (38). However, the specific location and configuration of
each
secondary fluid passage (76) may be varied as desired for any particular
application.
Further, each secondary fluid passage (76) is preferably circular on cross-
section. However, any other suitable shape may be used. As well, each
secondary fluid
passage (76) may be of any diameter and the diameters of each secondary fluid
passage
(76) comprising the flow tee need not be the same. Finally, as stated above,
the portion
of each secondary fluid passage (76) adjacent the outer wall (43) of the
housing (38)
preferably includes means for connecting an external production pipe (78) to
the
secondary fluid passage (76). The connecting means may be comprised of any
device,
structure or mechanism suitable for performing this connection function.
However,
in the preferred embodiment, the portion of the secondary fluid passage (76)
adjacent
the outer wall (43) is comprised of a threaded inner surface for engagement
with a
compatible threaded outer surface of the external production pipe (78).
Referring to Figures 3 and 6, the blowout preventer portion of the
apparatus (27), or the portion of the apparatus (27) performing the blowout
preventer
function, is comprised of the middle section (72) of the housing (38). As
stated
previously, the primary fluid passage (44) is defined centrally within the
middle
section (72) of the housing (38) and the polished rod (30) extends
therethrough.
Further, the middle section (72) of the housing (38) defines two rod ram
passages (80)
having a longitudinal axis extending through both passages (80) which
intersects the
longitudinal axis of the primary fluid passage (44) such that the rod ram
passages (80)
extend from the primary fluid passage (44) to opposing locations on the outer
wall (43)
of the housing (38) within the middle section (72). As a result, the rod ram
passages
(80) are aligned on opposing sides of the primary fluid passage (44), and thus
the
polished rod (30). Specifically, in the preferred embodiment, the longitudinal
axis of
the rod ram passages (80) is substantially perpendicular to the longitudinal
axis of the
primary fluid passage (44) and the polished rod (30).
A polished rod ram (82) is movably mounted within each rod ram
passage (80) such that each polished rod ram (82) may be selectively moved
within the
passage (80) into and out of engagement with the polished rod (30).
Preferably, an
outer surface (84) of the polished rod ram (82) seals with the adjacent
surface of the
housing (38) defining the rod ram passage (80). In the preferred embodiment,
the
outer surface (84) defines an aperture (86) about its entire outer surface
(84) for
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CA 02203091 1997-04-18
receiving an O-ring (88) or similar sealing device therein such that the seal
is provided
between the outer surface (84) and the adjacent surface of the housing (38).
Further, each polished rod ram (82) is comprised of an inner end (90)
facing the primary fluid passage (44) and an opposing outer end (92).
Preferably, as
shown in Figures 6-8, a polished rod ram packer (94) is mounted to the inner
end (90)
of the polished rod ram (82) for sealingly engaging the polished rod (30) when
the
polished rod ram (82) and polished rod ram packer (94) are moved into
engagement
therewith. In this manner, the polished rod ram (82) and polished rod ram
packer (94)
provide a seal with the polished rod (30) to prevent or inhibit the passage of
wellbore
fluids and pressure from the tubing string (24) through the apparatus (27) via
the
primary fluid passage (44).
To facilitate the sealing between the polished rod ram (82), including the
packer (94), and the polished rod (30), the inner end (90) of the polished rod
ram (82)
and the corresponding packer (94) define a groove (96) for receiving the
polished rod
therein. When the two polished rod rams (82) are moved into engagement with
the
polished rod (30), the groove (96) of each rod ram (82) and packer (94)
contacts and seals
with one half of the outer diameter of the polished rod (30). Thus, both rod
rams (82)
and packers (94) together contact and seal with the entire outer diameter of
the
polished rod (30).
The polished rod ram packer (94) may be comprised of any resilient,
elastic material capable of providing a seal with the polished rod (30), such
as rubber.
Further, although the packer (94), as shown in Figure 8, is preferably used
for sealing
with the polished rod (30), any mechanism, structure, device or apparatus
suitable for
providing a seal between the polished rod ram (82) and the polished rod (30)
may be
used.
The polished rod ram (82) may be of any shape suitable for performing its
intended purpose and function as described herein. Further, any means,
mechanism,
structure or device may be used for moving the polished rod ram (82) within
the rod
ram passage (80) such that the polished rod ram (82) is movable into and out
of
engagement with the polished rod (30). For instance, conventionally, the outer
portion of each rod ram passage (80) adjacent the outer wall (43) of the
housing (38)
may be internally threaded for receiving an externally threaded end cap (98)
therein.
Each end cap (98) defines an internally threaded aperture (99) therethrough
for
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CA 02203091 1997-04-18
receiving an externally threaded feed screw (100). When inserted, the feed
screw (100)
extends from an outer end (102) of the end cap (98) adjacent the outer wall
(43) of the
middle section (72) of the housing (38), through the end cap (98) towards the
polished
rod ram (82) for engagement with the outer end (92) of the polished rod ram
(82).
Thus, feeding of the feed screw (100) into the end cap (98) moves the polished
rod ram
(82) into engagement with the polished rod (30), while feeding of the feed
screw (100)
out of the end cap (98) moves the polished rod ram (82) out of engagement with
the
polished rod (30).
In this conventional polished rod ram (82) and end cap (98) structure, the
end of the feed screw (100) may engage the polished rod ram (82) at
substantially a
central location on the outer end (92) of the rod ram (82). Further, in such
conventional apparatus, the rod ram (82) may be round or square on cross-
section. In
the event the rod ram (82) is round or circular on cross-section, operation of
the feed
screw (100) may cause turning or rotation of the polished rod ram (82) within
the rod
ram passage (80). When the polished rod ram (82) is square on cross-section,
operation
of the feed screw (100) does not typically result in the movement or rotation
of the rod
ram (82) within the rod ram passage (80).
In the preferred embodiment of the apparatus (27), as shown in Figures 6,
9 and 10, the end cap (98) is not externally threaded, but rather, is
maintained or
mounted within the rod ram passage (80) by one or more fasteners (108), such
as bolts,
screws or the like. Further, the end of the feed screw (100) which engages the
rod ram
(82) includes a plunger portion (104). The plunger portion (104) is loosely
received
within a plunger recess (106) defined by the outer end (92) of the rod ram
(82), which
plunger recess (106) is not centrally located within the outer end (92). In
particular, the
plunger recess (106) is preferably positioned below a central axis passing
between the
inner and outer ends (90, 84) of the rod ram (82). The specific manner of
mounting the
end cap (98) and the non-axial plunger recess (106) permit the use of a rod
ram (82)
having a round or circular configuration on cross-section, while inhibiting
the
rotation of the rod ram (82) within the rod ram passage (80) upon operation of
the feed
screw (100). Thus, the grooves (96) in the rod ram (82) and the packer (94)
tend to stay
aligned with the polished rod (30) such that the polished rod (30) may be
easily
received therein.
Referring to Figure 3, in the preferred embodiment, the longitudinal axis
of the rod ram passages (80) is located in a first vertical plane and the
longitudinal axis
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CA 02203091 1997-04-18
of the secondary fluid passages (76) is located in a second vertical plane.
Preferably, the
first vertical plane is substantially perpendicular to the second vertical.
This
orientation permits or facilitates relatively easy access to the secondary
fluid passages
(76) for connection of external production pipes (78) and to the feed screws
(100) for
operation of the rod rams (82). However, any desired angle may be formed
between
the first and second vertical planes.
Finally, as stated, the tubing rotator portion of the apparatus (27), or the
portion of the apparatus (27) performing the tubing rotator function, is
comprised of
the lower section (70) of the housing (38). Further, the tubing rotator is
comprised of a
supported member (110) having an upper end (112) and a lower end (114) for
connecting, either directly or indirectly, to the tubing string (24). Further,
the tubing
rotator is comprised of a supporting structure for rotatably supporting the
supported
member (110) such that the tubing string (24) is rotatably suspended within
the
wellbore. Thus, the supporting structure permits the rotation of the supported
member (110), while supporting the supported member (110) such that at least
the
upper end (112) of the supported member (110) is contained within the lower
section
(70) of the housing (38).
Preferably, the supported member (110) is tubular such that a bore (116) of
the supported member (110) forms a portion of the primary fluid passage (44)
extending through the apparatus (27). Thus, the polished rod (30) is passed
through
the bore (116) of the supported member (110). Further, preferably, an outer
surface
(118) of the supported member (110) at its upper end (112) sealingly engages
the
adjacent surface of the lower section (70) of the housing (38). Further, a
spaced distance
is preferably provided between the upper end (112) of the supported member
(110) and
the adjacent surface of the housing (38) in order to provide a relatively
loose fit
between the housing (38) and upper end (112) of the supported member (110).
The supporting structure preferably engages the wellhead (20), and more
preferably, the uppermost surface of the wellhead flange (22). However, the
supporting structure may engage further wellhead equipment located between the
apparatus (27) and the wellhead (20). The supporting structure may be
comprised of
any members, elements, structure, device, apparatus or mechanism suitable for
rotatably supporting the supported member (110) such that the tubing string
(24)
connected to the supported member (110) is rotatably supported within the
wellbore.
Further, the supporting structure, as indicated above, may engage the wellhead
(20),
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CA 02203091 1997-04-18
and in particular the wellhead flange (22), in any suitable manner permitting
the
supporting structure to perform its intended function. As well, the supporting
structure may rotatably support the supported member (110) in any manner or by
any
means or mechanism suitable for performing this intended function. In other
words,
any known tubing rotators and tubing rotator structures comprising a supported
member (110) and a supporting structure, as described herein, may comprise the
tubing
rotator of the apparatus (27).
However, in the preferred embodiment, the supporting structure is
comprised of a support flange (120) for mounting on the wellhead (20).
Preferably, the
support flange (120) is mounted upon the uppermost surface of the wellhead
flange
(22). Thus, in the preferred embodiment, as shown in Figure 4, the support
flange
(120) rests upon and is supported by the wellhead flange (22). A seal ring
(122) is
preferably located between the lowermost surface of the support flange (120)
and the
uppermost surface of the wellhead flange (22) to prevent the passage of
wellbore
annulus fluids therebetween.
The support flange (120) may directly support the supported member
(110), however, in the preferred embodiment, the support flange (120)
indirectly
supports the supported member (110) by an outer member (124). Thus, in the
preferred
embodiment, the supporting structure is comprised of the support flange (120)
and the
outer member (124). Preferably, the support flange (120) and the outer member
are
completely or partially contained within the lower section (70) of the housing
(38),
although they need not be. Further, the support flange (120) is preferably
sized and
shaped such that when it is supported by, or resting upon, the wellhead flange
(22), the
support flange (120) is contained within the circumference of the apertures in
the
wellhead flange (22) comprising the bolt ring.
In the preferred embodiment, the support flange (120) is tubular in shape
and is detachably engaged with the outer member (124) such that the outer
member
(124) may be disengaged from the support flange (120) as desired.
Specifically, an inner
surface of the support flange (120) engages an outer surface of the outer
member (124).
The inner surface of the support flange (120) is shaped to be compatible with
the outer
surface of the outer member (124) in order to facilitate sealing of the
surfaces and so
that the outer member (124) may be seated upon and supported by the support
flange
(120). The specific shape of the seating arrangement between the surfaces may
vary
from a gradual angled slope of the outer surface of the outer member (124) to
a vertical
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CA 02203091 1997-04-18
slope containing a protruding horizontal shoulder at any point along the outer
surface
of the outer member (124). Preferably, the outer surface of the outer member
(124) and
the inner surface of the support flange (120) are sealingly engaged.
Specifically, in the
preferred embodiment, the two surfaces are sealingly engaged by a sealing
assembly
comprised of two O-rings mounted within O-ring grooves on the outer surface of
the
outer member (124).
In the preferred embodiment, a lower end (128) of the outer member (124)
extends downward inside the wellhead flange (22) when the outer member (124)
is
mounted on the support flange (120). Preferably, the shape of the lower end
(128) of
the outer member (124) is not dependent upon the shape of the inner surface of
the
wellhead flange (22). Although the shapes of the outer surface of the lower
end (128)
of the outer member (124) and the inner surface of the wellhead flange (22)
may be
compatible to engage each other, this is neither necessary nor preferred in
the preferred
embodiment. The two surfaces are not required to be sealingly engaged for
operation
of the apparatus (27). Further, in the preferred embodiment, the lower end
(128) of the
outer member (124) extends downward from the wellhead flange (22) and
specifically
into the casing bowl (34) without conforming to its shape in order that the
apparatus
(27) may be more easily retrofit to varying shapes and sizes of casing bowls
(34) in
existing wellheads.
Referring to Figure 4, the wellhead flange (22) preferably includes two
holddown screws (130) which extend through the wellhead flange (22) through a
bore
from its outer surface to its inner surface. A nose (136) of each holddown
screw (130) is
engagable with the outer surface of the outer member (124) when the outer
member
(124) is suspended from the support flange (120). The outer surface of the
outer
member (124) includes a compatible engagement surface (138) for receiving the
nose
(136) of each holddown screw (130). The holddown screws (130) are moveable
within
the bore of the wellhead flange (22) such that the holddown screws (130) are
adjustable
in order that the nose (136) may be moved into and out of engagement with the
engagement surface (138) as desired for operation or servicing of the wellhead
(20).
When the holddown screws (130) are loosened or moved away from the engagement
surface (138), the outer member (124) may be removed from the wellhead flange
(22).
Conversely, when the holddown screws (130) are tightened and moved into
engagement with the engagement surface (138), longitudinal movement of the
outer
member (124) relative to the wellhead flange (22) is prevented.
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CA 02203091 1997-04-18
In the preferred embodiment, the inner surface of the outer member (124)
includes a shoulder (140) which extends towards the polished rod (30). A
bearing (142)
is seated on the shoulder (140). The bearing (142) may be any bearing suitable
for its
intended purpose, however, preferably the bearing (142) is comprised of a
thrust
bearing. A compatible shoulder (144) on the outer surface of the supported
member
(110) is then seated on the bearing (142) such that the supported member (110)
is
rotatably supported upon the outer member (124). In this manner, the downward
longitudinal movement of the supported member (110) relative to the outer
member
(124) is inhibited.
Further, the outer surface of the supported member (110) preferably
sealingly engages the inner surface of the outer member (124). The two
surfaces may
be sealingly engaged by any sealing assembly, such as one or more O-rings
mounted in
O-ring grooves on the outer surface of the supported member (110). Further, a
bushing
(146), preferably a radial bushing, is also located between the supported
member (110)
and the outer member (124).
In the preferred embodiment, the apparatus (27) further includes means
for securing the supported member (110) to the outer member (124) such that
upward
longitudinal movement of the supported member (110) relative to the outer
member
(124) is inhibited. The securing means are preferably comprised of a retaining
ring
(148) secured to the supported member (110) adjacent to the lower end (128) of
the
outer member (124). The retaining ring (148) is preferably removable in order
to
permit upward longitudinal movement of the supported member (110) as necessary
for servicing.
Finally, the tubing rotator is further comprised of means for rotating the
supported member (110) within the supporting structure while the supporting
structure remains stationary in order that the tubing string (24) is rotated
within the
wellbore. Any rotating means, mechanism, device, apparatus or gear system
suitable
for and capable of performing this function or purpose may be used. In the
preferred
embodiment, the supported member (110) includes a crown gear (150), and the
rotating
means are comprised of a rotatable pinion (152), releasably engaged with the
crown
gear (150), and means for driving the pinion (152) such that rotation of the
pinion (152)
rotates the supported member (110) within the supporting structure.
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CA 02203091 1997-04-18
The driving means for the pinion (152) is preferably comprised of a
pinion shaft (154), connected to the pinion (152), and means for driving the
pinion
shaft (154). The lower section (70) of the housing (38) defines a pinion
passage (156) for
passage of the pinion shaft (154) therethrough for engagement of the pinion
(152) with
the crown gear (150). Thus, the pinion shaft (154) has a first end (158)
extending into
the housing (38) through the pinion passage (156) for connection to the pinion
(152)
and a second end (160) outside of the housing (38) for connection to the
driving means
of the pinion shaft (154). The pinion (152) and the crown gear (150) are
contained
within the lower section (70) of the housing (38). The pinion shaft (154) may
be
rotatably supported within the pinion passage (156) by any means, structure,
mechanism or device suitable for its intended purpose.
As stated, the second end (160) of the pinion shaft (154) is adapted to be
connected to the driving means. The driving means is comprised of a gear box
(162) in
the preferred embodiment. The gear box (162) may be operated manually or may
be
driven automatically by the reciprocating action of a walking beam as shown in
Figure
1, or by the rotation of a rotating polished rod (30) as shown in Figure 2. In
all modes
of operation, the gear box (162) provides means for creating a mechanical
advantage
which facilitates the generation of sufficient torque to turn the pinion shaft
(154) in
order to rotate the supported member (110).
In the preferred embodiment as shown in Figure 3, a longitudinal axis of
the pinion passage (156) is preferably located in a third vertical plane. The
third
vertical plane preferably forms about a 45 degree angle with the second
vertical plane
including the secondary fluid passage (76) and the first vertical plane
including the rod
ram passages (80). In this manner, each of the elements of the tubing rotator,
flow tee
and blowout preventer are readily accessible by the operator of the apparatus
(27).
However, the first, second and third vertical planes may intersect at any
angle.
In a first alternate embodiment of the apparatus (27) as shown in Figure
11, the supporting structure comprising the tubing hanger is comprised of the
lower
section (70) of the housing (38). In particular, the lower surface (62) of the
base plate
(60) comprising the housing (38) includes an inwardly projecting shoulder
(164). The
shoulder (164) preferably sealingly engages the outer surface of the supported
member
(110). Specifically, the shoulder (164) includes one or more apertures for
containing an
O-ring, or like sealing means, for sealing against the outer surface of the
supported
member (110). Further, a bearing (142) is preferably located between the
shoulder (144)
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CA 02203091 1997-04-18
on the outer surface of the supported member (110) and the shoulder (164) of
the base
plate (60). The bearing (42) may be comprised of any bearing suitable for its
intended
purpose, however, the bearing (142) is preferably a radial bearing or a
tapered roller
bearing.
Referring to a third alternate embodiment of the invention, as shown in
Figure 13, where the casing bowl (34) includes a tapered inner surface (36),
the
supporting structure may be comprised of an outer member (166) having a
tapered
outer surface compatible with the tapered inner surface (36) of the casing
bowl (34). In
this manner, the outer surface (168) of the outer member (166) engages the
inner
surface (36) of the casing bowl (34) such that the downward longitudinal
movement of
the outer member (166) relative to the casing bowl (34) is prevented. In this
instance,
as with the preferred embodiment of the apparatus (27), the outer member (166)
includes an inwardly projecting shoulder (170) which engages and supports
thereon an
outwardly directed shoulder (144) on the supported member (110). A bearing
(142) is
located between the shoulder (144) of the supported member (110) and the
shoulder
(170) of the outer member (166).
Further, referring to the third alternate embodiment of the apparatus (27),
the supported member (110) may be comprised of an upper supported member (172)
and a lower supported member (174). The supporting structure for the upper
supported member (172) is comprised of the base plate (60). The supporting
structure
of the lower supported member (174) is comprised of the tapered outer surface
(168) of
the outer member (166) which engages the inner surface (36) of the casing bowl
(34). In
this particular embodiment, use of one of the supporting structures alone may
be
sufficient to support the entire supported member (110), including both the
upper
supported member (172) and the lower supported member (174). However, in the
third alternate embodiment, both supporting structures are preferably used.
Referring to Figure 12, in a second alternate embodiment of the
invention, the supported member (110) is similarly comprised of an upper
supported
member (172) and a lower supported member (174). Again, the upper supported
member (172) is rotatably supported by a supporting structure comprising the
base plate
(60). The supporting structure for the lower supported member (174) is
comprised of a
support flange (120) for mounting on the wellhead (20). More particularly, the
supporting structure for the lower supported member (174) is comprised of a
support
flange (120) and an outer member (124) similar to those provided for in the
preferred
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CA 02203091 1997-04-18
embodiment shown in Figure 4. Again, use of both of the supporting structures
may
not be required. However, in the preferred second alternate embodiment, both
of the
supporting structures are used to rotatably support the complete supported
member
(110).
In each of the second and third alternate embodiments, as shown in
Figures 12 and 13 respectively, the upper supported member (172) and the lower
supported member (174) are preferably connected or engaged with each other
such that
the upper and lower supported members (172, 174) rotate concurrently as a
single
supported member (110) unit. Any mechanism, structure, device or apparatus
suitable
for engaging a lower end (176) of the upper supported member (172) with the
upper
end (178) of the lower supported member (174) may be used. For instance, the
lower
end (176) of the upper supported member (172) may include splines compatible
with
splines located on the upper end (178) of the lower supported member (174).
However, in the preferred second and third alternate embodiments, the
connection or engagement between the upper and lower supported members (172,
174)
is comprised of a dowel pin connection (180). The dowel pin connection (180)
is
comprised of one or more holes (182) defined about the circumference of the
upper
end (178) of the lower supported member (174). The dowel pin connection (180)
is
further comprised of a dowel pin (184) associated with each hole (182) in the
lower
supported member (174). Each dowel pin (184) includes a first end (186)
mounted or
otherwise affixed within the hole (182) and a second end (188) extending from
the hole
(182) towards the lower end (176) of the upper supported member (172).
Finally, the
dowel pin connection (180) is comprised of a drive ring (190) mounted about
the lower
end (176) of the upper supported member (172). The drive ring (190) defines a
hole
(192) for receiving each of the second ends (188) of the dowel pin (184). Each
of the
holes (192) in the drive ring (190) is preferably tapered at both the top and
bottom
surfaces to guide the dowel pin (184) within the hole (192) as shown in Figure
15.
The drive ring (190) may be rigidly affixed to the lower end (176) of the
upper supported member (172) by any suitable fastening means, device or
mechanism.
However, in the preferred embodiment, the drive ring (190) defines at least
two
threaded holes (194) extending from the outer circumference of the drive ring
(190) to
the inner circumference of the drive ring (190) such that set screws or like
fasteners
may be passed therethrough. Thus, the set screws (not shown) extend from the
outer
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CA 02203091 1997-04-18
circumference of the drive ring (190) through the drive ring (190) for
engagement with
the lower end (176) of the upper supported member (172).
The dowel pin connection (180) may be comprised of any number of
dowel pins (184) sufficient to provide a relatively strong connection between
the upper
and lower supported members (172, 174). In the preferred embodiment, the dowel
pin
connection (180) is comprised of ten dowel pins (184) arranged within ten
holes (182)
in the upper end (178) of the lower supported member (174), which holes (182)
are
arranged circumferentially about the upper end (178) of the lower supported
member
(174). The drive ring (190) is comprised of at least one hole (192) for
receiving each of
the dowel pins (184). However, a greater number of holes (192) may be provided
by the
drive ring (190). In the preferred embodiment, the drive ring (190) defines
twenty
holes (192) for receiving the dowel pins (184) therein.
Finally, as shown in Figure 16, the upper end (178) of the lower supported
member (174) preferably defines a plurality of keyways (196) about its outer
circumference. The adjacent inner circumference of the outer member (124)
defines at
least one matching keyway (198). When servicing the apparatus (27), removal of
the
lower supported member (174) and the adjacent outer member (124) may be
achieved
in the following manner. First, one of the keyways (196) defined by the outer
circumference of the upper end (178) of the lower supported member (174) is
aligned
with the keyway (198) on the inner circumference of the outer member (124). A
key
(not shown) is then inserted into the aligned keyways (196, 198) in order to
lock the
lower supported member (174) and the outer member (124) in position such that
relative rotation is no longer permitted. The housing (38) of the apparatus
(27) is then
removed and a servicing blowout preventer is installed on the wellhead (20). A
pup
joint (not shown) or other structure may then be screwed into an internal
threaded
surface of the lower supported member (174) such that the lower supported
member
(174) and the outer member (124) may be removed through the servicing blowout
preventer.
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