Note: Descriptions are shown in the official language in which they were submitted.
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1 BLOWOUT PREVENTER AND RAMS
2 BACKGROUND
3 Wellhead blowout preventers are used in oil wellhead assemblies to seal
against
4 a central bore. In a pumping production wellhead, the blow out preventer
(BOP) may
be configured to seal against a polish rod or a tubular member if present. The
rams of
6 a BOP may operate in different ways in closing off a well, or multiple
BOPS may be
7 used in a wellhead stack to provide different functions. In a production
pumping well,
8 opposing polish rod BOP rams accommodate and seal around a polish rod
extending
9 generally vertically through the wellhead. Blind BOP rams seal against
each other
across the central bore when no polish rod is in place.
11 A typical prior art BOP for a production wellhead is disclosed in U.S.
Patent No.
12 5,765,813 to Lam et al., issued Jun. 16, 1998, owned by Stream-Flo
Industries Ltd., the
13 assignee of this patent application. This type of BOP is commonly used
in connection
14 with pumping production wells. With such wells, a sucker rod string is
reciprocated or
rotated to drive a downhole pump, which lifts the produced fluid to the
surface through a
16 tubing string. The BOP is equipped with a pair of opposing polish rod
rams which can
17 be advanced horizontally to seal around the vertical polish rod portion
of the rod string
18 to prevent the upward escape of fluid. Alternatively, if the rod string
is out of the well,
19 the inner or front ends of the rams can be pressed together to cause
closure of the
wellhead assembly fluid passageway.
21 More particularly, a typical pumping production BOP includes a cross-
shaped
22 housing forming a central, generally vertical bore and a pair of
coaxial, horizontal ram
23 bores intersecting the central bore from each side. The BOP is commonly
positioned in
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1 the wellhead assembly between the tubing head and flow tee. In this
configuration, the
2 central bore of the BOP forms part of the wellhead assembly fluid
passageway. Within
3 the BOP, a pair of rams is positioned in the horizontal ram bores.
Actuator
4 mechanisms, which generally include rams screw powered by mechanical,
electrical,
pneumatic or hydraulic actuators, are provided at the outer ends of the ram
bores, for
6 extending or retracting the rams into or out of the central bore, in
order to close or open
7 the central well bore. Each BOP ram comprises a generally cylindrical
body, although
8 other shaped ram bodies are known (ex. oval, rectangular or square in
cross section).
9 The ram generally comprises a steel core, preferably having an outer full
bore diameter
portion (or rear portion) and a reduced diameter inner portion (or front
portion). The
11 ram core inner portion is covered with and bonded to a layer of an
elastomeric material,
12 typically a nitrile rubber. The ram bores, typically cylindrical, extend
into the central
13 bore and the bore surfaces combine at their intersection to form sealing
areas. When
14 the rams move into the central bore, the rubber surfaces of their inner
portions seal
against the sealing surfaces.
16 The rubber-coated inner or front face of each ram is typically formed
to provide a
17 semi-circular, vertically directed groove, also termed vertical radial
groove. When the
18 polish rod of the rod string is present in the central bore, opposing
ram ends encircle
19 and press against the polish rod to form a seal of the central bore.
When the polish rod
is not present the ram ends compress together to form a solid block. In both
cases, the
21 circumferential seals of the ram side surfaces, with the sealing areas
and the end face
22 seals, combine to close the central bore and contain pressurized fluids.
23 U.S. Patent No. 7,673,674, issued March 9, 2010 to Tony M. Lam, and
assigned
24 to Stream-Flo Industries Ltd., the assignee for this patent application,
describes a BOP
ram and/or polish rod claim in which the vertically directed groove at the
front face of
26 the ram is shaped as a V-groove to accommodate a portion of the
circumference of the
27 polish rod. U.S. Patent No. 7,552,765 to Tony M. Lam, issued June 30,
2009, and
28 assigned to Stream-Flo Industries Ltd., describes a BOP in which one of
the rams is
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1 formed with an extended central bore sealing section behind the front
sealing end of the
2 ram, such that the extended central bore sealing section can be extended
across the
3 central bore to seal the central bore when the polish rod is not present.
4 In a production BOP, pressure acting from below on the closed BOP rams
may
extrude the side rubber upwardly so that the circumferential seal with the
sealing areas
6 is lost. As well, the end rubber bonded to the vertical end faces (front
faces) of the ram
7 cores may tear loose from the core when high pressure is exerted from
below. In
8 severe conditions, such as injecting chemicals to close off a well, the
rubber degrades
9 quickly, causing the seals to fail. A large number of BOP ram designs
exist to address
problems of extrusion, tearing or degradation of the BOP ram seals.
11 Canadian Patent Application No. 2,260,655, published Aug. 2, 2000
naming
12 Tony M. Lam and Keith D. Farquharson as inventors and Stream-Flo
Industries Ltd. as
13 assignee, describes a ram type BOP for high temperature applications.
The BOP
14 incorporates a generally L-shaped seal element formed of a graphite or
asbestos seal
material, which is sandwiched between a bottom L-shaped steel retainer plate
and a
16 semi-cylindrically shaped steel top retainer plate. This design of BOP
ram is well suited
17 for brittle seal materials such as graphite and asbestos when higher
temperatures are
18 encountered.
19 Other ram type BOP devices exist which use graphite or asbestos type
seals or
seal inserts. However, graphite and asbestos type sealing materials typically
include
21 polymeric bonding materials which have lower temperature limits than
graphite or
22 asbestos, so the seals are prone to failure at very high temperatures,
such as
23 temperatures above 600 F. Today, high temperature wellhead applications
such as
24 steam injection may require the wellhead equipment to accommodate
temperatures
above 600 F. Also, the use of asbestos seal materials is being phased out in
industry
26 due to harmful effects of asbestos fibres in handling, manufacture and
in use.
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1 Thermoplastic materials having superior chemical resistance are
available, but
2 have different compressibility and elastic properties than elastomeric
sealing materials
3 such as nitrile rubbers. Thus, BOP devices are not generally amenable to
simple
4 substitution of thermoplastics for the rubber sealing components. U.S.
Patent No.
7,137,610, issued to Lam on November 22, 2006, and assigned to Stream-Flo
6 Industries Inc., describes a production BOP and BOP rams incorporating
thermoplastic
7 seals at the front of the rams to seal against the polish rod. However,
even
8 thermoplastic materials have temperature limits below the temperatures
encountered
9 for steam injection wellheads.
In spite of the above advances in BOP ram seals, there is still a need for BOP
11 devices capable of withstanding very high or very low temperature
environments. For
12 instance, in wellheads through which steam is injected to enhance
recovery in depleted
13 wells or for heavy oil wells, temperatures in excess of 650 F can be
reached. These
14 temperatures far exceed the limits of nitrile rubber seals, elastomeric
seal materials,
and thermoplastic seal materials. As above, BOP devices adapted to carry
graphite or
16 asbestos seals are also subject to failure at such extreme temperatures
as polymeric
17 bonding materials in the seals begin to break down. As well, at very low
temperatures,
18 conventional BOP sealing materials become very hard or brittle,
interfering with the
19 ability to make reliable seals.
There is a still a need for a ram type BOP which can reliably seal against a
polish
21 rod and/or the central bore of a wellhead in very high temperature and
very low
22 temperature applications.
23 SUMMARY
24 In one broad aspect, there is provided a ram type blowout preventer
such as
may be used in a pumping production well. The blowout preventer includes:
26 a) a housing forming a central bore extending generally vertically
through the
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1 housing, and a pair of ram bores extending radially outwardly in opposite
directions
2 through the housing and intersecting the central bore;
3 b) a steel bodied ram positioned in each of the pair of ram bores to
provide
4 opposing rams, the ram having a front end portion, a rear end portion, a
top portion and
a bottom portion and being adapted for sliding movement in the ram bore
between an
6 extended position, with the front end portion extending across the
central bore and the
7 rear end portion within the ram bore, and a retracted position within the
ram bore, the
8 ram being configured with a front face to seal against the front face of
the opposing ram
9 and to accommodate and seal against a tubular member or rod, if present
in the central
bore;
11 c) a ram actuating mechanism connected to the rear end portion of the
ram for
12 extending and retracting the ram between the extended and retracted
positions;
13 d) a seal on the ram, the seal extending across the front face, then
rearwardly, and
14 then either upwardly over the top portion or downwardly over the bottom
portion, at a
position rearwardly of the front end portion; and
16 e) the front face of the ram forming a leading edge portion located
either above or
17 below the seal so that, as the opposing rams are moved into the extended
position, the
18 leading edge portions of the opposing rams abut and press against each
other,
19 imparting a generally vertical movement to the opposing rams to bring
the seals on the
front faces into sealing engagement with each other and to energize the seals
21 extending over the top portion or the bottom portion against the ram
bores;
22 f) whereby, in the extended position, the seals on the opposing rams
seal against
23 each other, against the tubular member or rod if present, and also seal
the central bore.
24 In some embodiments, the front face of the ram includes an inclined
portion such
that a plane through the inclined portion is inclined toward the central bore,
and the
26 inclined portion is adapted to be brought into contact with the inclined
portion on the
27 opposing ram by the generally vertical movement imparted to the opposing
rams. In
28 this embodiment, the seal may be located on the inclined portion of the
ram such the
29 seals on the front faces of the opposing rams seal against each other as
the inclined
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1 portions of the rams contact each other.
2 In some embodiments, the ram actuating mechanism includes a ram screw
3 connected to the rear end portion of the ram at a point either above or
below a center
4 axis of the ram bore to facilitate imparting the generally vertical
movement to the ram in
the extended position.
6 In some embodiments, the front face of the ram may be formed with a
cut away
7 portion located above or below the seal to allow the ram to flex in the
ram bore. In
8 some embodiments the cut away portion is a horizontal slot extending
across the front
9 face and rearwardly in the ram.
In some embodiments the front face of the ram may form the inclined portion in
a
11 manner such that a plane through the front face is inclined top to
bottom toward the
12 central bore, and such that the leading edge portion is formed adjacent
the top portion
13 of the ram.
14 In other embodiments, the leading edge portion on the front face of
the ram is a
flattened planar portion formed adjacent either the top portion or the bottom
portion of
16 the ram, such that a plane through the flattened portion is generally
vertical.
17 The seal of the blowout preventer may be formed as an elastomeric, a
18 thermoplastic seal, or a rope packing seal. For a rope packing seal, the
seal may be
19 formed from a length or a loop of a rope packing material which can
accommodate very
high and/or very low temperatures. The seal may be formed as a primary rope
packing
21 seal formed from a first length or loop of rope packing extending across
the front face,
22 then rearwardly, and then upwardly over the top portion of the ram at a
position
23 rearwardly of the front end portion of the ram, with the primary rope
packing seal being
24 held in, so as to protrude radially outwardly from, a continuous first
groove formed in the
ram.
6
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1 In some embodiments, the blowout preventer includes a primary rope
packing
2 seal which extends across the front face of the ram with a vertical
offset relative to the
3 primary rope packing seal on the front face of the opposing ram, such
that in the
4 extended position, the primary rope packing seals on the opposing rams
seal against
each other but with the vertical offset.
6 In some embodiments, the blowout preventer may include a secondary
rope
7 packing seal formed on the ram from a second length or loop of rope
packing extending
8 across the front face, and being spaced from the primary rope packing
seal. The
9 secondary rope packing seal is held in, so as to protrude radially
outwardly from, a
second groove formed in the ram. The secondary rope packing seal may extend
11 across the front face of the ram with a vertical offset relative to the
secondary rope
12 packing seal on the front face of the opposing ram, such that in the
extended position,
13 the secondary rope packing seals on the opposing rams seal against each
other but
14 with the vertical offset.
In another broad aspect, there is provided a ram type blowout preventer which
16 includes:
17 a) a housing forming a central bore extending generally vertically
through the
18 housing, and a pair of ram bores extending radially outwardly in
opposite directions
19 through the housing and intersecting the central bore;
b) a steel bodied, full bore ram positioned in each of the pair of ram
bores to
21 provide opposing rams, the ram having a front end portion, a rear end
portion, a top
22 portion and a bottom portion and being adapted for sliding movement in
the ram bore
23 between an extended position, with the front end portion extending
across the central
24 bore and the rear end portion within the ram bore, and a retracted
position within the
ram bore, the ram being configured with a front face to seal against the front
face of the
26 opposing ram and to accommodate and seal against tubular member or rod,
if present
27 in the central bore;
28 c) an actuating mechanism connected to the rear end portion of the
ram for
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1 extending and retracting the ram between the extended and retracted
positions,
2 d) each ram comprising:
3 i. a body component forming the bottom portion of the ram,
the body
4 component having a front portion, a rear portion, a front end
and a rear
end;
6 ii. a seal component forming the top portion of the ram and
extending
7 rearwardly of the front end portion of the ram, the seal
component having
8 a front portion, a rear portion, a front end, a rear end, and a
front face;
9 iii. the body component having a cut-out in its front portion
to provide
a seal support surface to support the seal component, the seal support
11 surface being inclined front to rear such the seal component
rides
12 upwardly and rearwardly on the seal support surface;
13 iv. the seal component having an inner surface which
generally
14 conforms to the seal support surface of the body component;
v. the body component and seal component combining, in an
16 assembled form, to form the full bore ram, which when out of the
17 extended position has the front end of the seal component
forming a
18 leading edge portion which protrudes a horizontal distance
beyond the
19 front end of the body component; and
vi. connectors for connecting the seal component and the body
21 component while allowing the seal component, in the extended
position,
22 to be pressed against the seal support surface of the body
component
23 and to ride upwardly and rearwardly on the seal support surface;
and
24 e) a primary rope packing seal formed on the seal component of the
ram from a
first length or loop of rope packing, the primary rope packing seal extending
across the
26 front face of the seal component, rearwardly, and then upwardly over the
top portion of
27 the ram at a position rearwardly of the front end portion of the ram,
the primary rope
28 packing seal being held in, so as to protrude radially outwardly from, a
continuous first
29 groove formed in the seal component;
f) such that, in the extended position, the primary rope packing seals on
the
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1 opposing rams seal against each other, against the tubular member or rod
if present,
2 and also seal the central bore.
3 The front face of the BOP ram may be formed with a vertical groove to
4 accommodate a polish rod or other tubular member. In some embodiments the
vertical
groove is a radial groove. In other embodiments the vertical groove is a V-
groove with
6 the seal(s) extending across a raised radial backing section formed in
the V-groove to
7 seal to the tubular member or rod. In yet other embodiments the front
face of the BOP
8 ram body is formed as a blind ram to seal against an opposing ram without
the polish
9 rod.
The blowout preventer of any of these embodiments may be configured as a
11 wellhead assembly which may include the BOP alone, or in a stack with
one or more
12 other wellhead components. The blowout preventer of any of these
embodiments may
13 alternatively be included in a wellhead assembly provided as an integral
composite
14 assembly with one or more other wellhead components which might include,
in any
sequence, adaptors, control valves, additional BOPS, check valves, a flow tee,
and a
16 polish rod clamp. The wellhead assembly of any of these embodiments
includes top
17 and bottom connectors for connecting to wellhead components located
above and
18 below. Such connectors may be of any type, as is known in the industry,
including for
19 example studded connectors, flange connections, welded connections,
clamp and
threaded connections. Also provided are the BOP rams configured as set out for
any of
21 the embodiments described herein.
22 The rams and ram bores may be of any shape or configuration as is known
in
23 the BOP industry. While the figures show the rams and ram bores as being
cylindrical
24 in cross-section, they may be alternatively shaped, such as oval in
cross section. As
used herein, the term "cylindrical" is understood to include rams and ram
bores which
26 are generally circular or oval in cross section.
9
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1 It should be understood that the terms "front", "rear", "upper",
"lower", "inner",
2 "outer", "top" and "bottom", as used herein and in the claims with
reference to the
3 wellhead components and the BOP ram or its parts, refer to the component
or ram as it
4 is designed to be positioned in one of the horizontal ram bores, for
longitudinal
movement forwardly into the central bore or rearwardly in the horizontal ram
bores. By
6 "front", as used herein, is meant the portion or end of the ram or its
parts at the central
7 bore, or that is facing the central bore. By "rear" is meant the portion
or end of the ram
8 or its parts opposite the front. By "outer" is meant the outer
circumferential portion of
9 the ram or its parts. The term "central" in reference to the "central
bore" is meant to
include a generally vertical well bore which may be somewhat off-center in the
wellhead
11 assembly, or somewhat inclined relative to vertical, such as occurs in
horizontal or
12 inclined oil/gas wells. Thus the term "generally vertical", or
"vertical" is meant to include
13 well bores that are inclined relative to vertical, and wellhead
components configured to
14 accommodate such configurations. Similarly, the term "horizontal ram
bore" is meant to
include generally horizontal ram bores which intersect the central bore at
angles
16 generally perpendicular to the longitudinal axis of the central bore.
17
18 As used herein and in the claims, a reference to "a connection,"
"connected" or
19 "connect(s)" is a reference to a sealed pressure-containing connection
unless the
context otherwise requires.
21 As used herein, "comprising" is synonymous with "including,"
"containing," or
22 "characterized by," and is inclusive or open-ended and does not exclude
additional,
23 unrecited elements or method steps. The invention illustratively
described herein
24 suitably may be practiced in the absence of any element or elements,
limitation or
limitations which is not specifically disclosed herein.
26 The use of the indefinite article "a" in the claims before an element
means that
27 one of the elements is specified, but does not specifically exclude
others of the
28 elements being present, unless the context clearly requires that there
be one and only
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1 one of the elements.
2 BRIEF DESCRIPTION OF THE DRAWINGS
3 Figure 1 is a side view of one embodiment of a production blowout
preventer
4 (BOP) showing the housing, end plugs and ram screws in section, and
showing both of
the BOP rams in an extended sealing position against a polish rod.
6 Figure 2 is a perspective view of one of the BOP rams from Figure 1,
formed with
7 a radial vertical groove at its front face to accommodate a polish rod,
and showing a
8 primary rope packing seal, a secondary rope packing seal spaced from the
primary
9 rope packing seal, and a circumferential rope packing seal formed
rearwardly of the
primary and secondary rope packing seals. Each rope packing for these seals is
held
11 in continuous grooves formed in the ram.
12 Figure 3 is a side view of the BOP ram of Figure 2.
13 Figure 4 is side sectional view along line 4-4 of Figure 6, partially
cut away,
14 showing the overlapping ends of the primary rope packing seal at the top
portion of the
ram, and also showing a central T-slot at the rear of the ram to lock onto the
ends of a
16 ram screw used to extend and retract the ram.
17 Figure 5 is a partial front view of the ram of Figure 2 showing the
primary and
18 secondary rope packing seals extending across the vertical radial
groove.
19 Figure 6 is a top view of the ram of Figure 2, showing the primary rope
packing
seal overlapping ends at the top portion of the ram.
21 Figure 7 is a perspective view of the ram of Figure 2, with the primary
and
22 secondary rope packing seals removed, showing the dove-tail shaped
grooves to retain
11
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1 the lengths of rope packings.
2 Figure 8 is a perspective view of a further embodiment of a BOP ram
having a
3 blind front face for sealing across the central bore when a polish rod is
not present, and
4 incorporating primary and secondary rope packing seals.
Figure 9 is a perspective view of a further embodiment of a BOP ram having a V-
6 shaped vertical groove at its front face, and including the primary and
secondary rope
7 packing seals extending across a raised radial backing section formed in
the V-grove to
8 seal the polish rod.
9 Figure 10 is a perspective view of a further embodiment of a BOP ram
having an
alternate spacing arrangement of the primary and secondary rope packing seals.
11 Figure 11 is a top view of a further embodiment of a BOP ram, showing
joined
12 abutting ends of the primary rope packing seal and the circumferential
rope packing
13 seal, with the joined abutting ends both being located at the top
portion of the ram.
14 Figure 12 is a top view of a further embodiment of a BOP ram, showing
joined
abutting ends of the primary rope packing seal, and overlapping ends of the
16 circumferential rope packing seal, with the joined abutting ends and the
overlapping
17 ends being located at the top portion of the ram.
18 Figure 13 is a top view of a further embodiment of a BOP ram, showing
joined
19 abutting ends of the primary rope packing seal at the top portion of the
ram, and joined
abutting ends of the circumferential rope packing seal located at the bottom
portion of
21 the ram.
22 Figure 14 is a side view of another embodiment of a production blowout
23 preventer (BOP) with the housing, end plugs and ram screws in section,
and showing
12
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1 the opposing BOP rams being moved into an extended position with the
leading edge
2 portions on the ram front faces adjacent the top portions of the rams
making initial
3 contact with each other, and also showing the vertical offset of the rope
packing seals
4 at the front faces of the opposing rams, the horizontal slot in the rams
below the seals,
the inclined portions on the front faces of the rams, and the off center
connection of the
6 ram screws at the rear of the rams.
7 Figure 15 is a side view of the left side BOP ram of Figure 14 showing
the front
8 face of the ram being formed with an inclined portion which is inclined
top to bottom
9 toward the central bore, and showing a primary rope packing seal
extending rearwardly
along the side of the ram and over the top portion of the ram, a secondary
rope packing
11 seal spaced from the primary rope packing seal and extending rearwardly
along the
12 side of the ram to meet the primary rope packing seal.
13 Figure 16 is a side view of another embodiment of a BOP ram similar to
the ram
14 of Figure 15, but showing the leading edge portion adjacent the top
portion of the ram
formed as a flattened planar section such that a plane extending therethrough
is
16 generally vertical, whereby the flattened planar portions of opposing
rams meet in the
17 generally vertical plane at the initial point of contact with each
other.
18 Figure 17 is a front perspective view of the BOP ram of Figure 17 with
the
19 primary and secondary rope packing seals removed to show a continuous
first groove
to retain a first length of rope packing and having a widened portion at the
top portion of
21 the ram to accommodate overlapping ends of the first length of rope
packing, a second
22 groove for a second length of rope packing extending rearwardly to meet
the
23 continuous first groove, and a radial vertical groove formed at the
front face of the ram
24 to accommodate a polish rod.
Figure 18 is a front perspective view of the BOP ram of Figure 18 with the
26 primary and secondary rope packing seals held in the grooves so as to
protrude radially
13
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1 outwardly from the grooves.
2 Figure 19 is a side sectional view taken along line 1 9-1 9 of Figure
18, partially
3 cut away, at the rear end portion of the BOP ram, to show the primary
rope packing
4 seal at the top portion of the ram for sealing against the ram bore, and
to show the T-
S slot at the rear end of the ram for the off center connection, below the
center axis of the
6 ram bore, to the ram screw.
7 Figure 20 is a front perspective view of a BOP ram similar to the BOP
ram of
8 Figure 18, but showing a vertical groove which is V-shaped to accommodate
at least a
9 portion of the circumference of the polish rod within the V-groove, and
showing the
primary and secondary rope packing seals extending across a raised radial
backing
11 section formed in the V-groove to seal the polish rod.
12 Figure 21 is a front perspective view of a BOP ram similar to the BOP
ram of
13 Figure 18, but showing a front face formed as a blind ram such that the
front faces of
14 opposing rams seal against each other in the extended position to seal
the central bore.
Figure 22 is a front perspective view of a BOP ram similar to the ram of
Figure
16 18, but showing the primary and secondary rope packing seals configured
with the
17 alternate spacing arrangement as shown in Figure 10.
18 Figure 23 is a side view of an alternate embodiment of a production
BOP ram
19 formed with a bottom body component and a top seal component, the
components
being connected and configured such that the seal component, in the extended
21 position, is pressed against an inclined seal support surface of the
body component and
22 rides upwardly and rearwardly on the seal support surface. The BOP ram
is shown to
23 include primary and secondary rope packing seals formed on the seal
component.
14
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1 DESCRIPTION OF THE PREFERRED EMBODIMENTS
2 Multiple embodiments of a production blowout preventer (BOP) and BOP
rams
3 adapted for a production pumping BOP are shown in the Figures, with like
parts being
4 labeled with the same reference numerals. In Figures 1-13, the BOP rams
are
configured with generally parallel planar front faces, and provide primary
rope packing
6 seals, and optionally secondary rope packing seals and circumferential
rope packing
7 seals. In Figures 14-23, the BOP rams may be configured with a leading
edge portion
8 at the front faces of the opposing rams to abut and press against each
other in the
9 extended position so as to impart a generally vertical movement to the
opposing rams.
Alternatively, or in addition, the BOP rams of Figures 14-23 may be configured
such
11 that the seals across the front faces of the opposing rams have a
vertical offset such
12 that the seals seal against each other, but with the vertical offset.
13 Having reference to Figure 1, a production blowout preventer (BOP) is
shown
14 generally at 10, to include a cross-shaped, pressure-containing steel
housing 11
forming a central bore 12, extending generally vertically through the housing
11, and a
16 pair of co-axial horizontal ram bores 14. The ram bores 14 are slightly
larger in
17 diameter than the central bore 12, as is common in BOP devices. Top and
bottom
18 flange connectors 15, 16 to wellhead components located above and below
the BOP 10
19 are shown, although alternate top and bottom connectors such as
threaded, welded,
studded, or clamp connections may be used. The horizontal ram bores 14
intersect
21 with the central bore 12. The polish rod P is shown in place in the
central bore 12. The
22 polish rod P is an example of a tubular member which may be present in
the central
23 bore.
24 A pair of generally cylindrical BOP rams 18 are shown in Figure 1. Each
of the
rams 18 may be formed in multiple parts, but are generally cylindrically
shaped when
26 assembled for close fitting relationship in, and optionally for sealing
to, the ram bores
27 14. The rams 18 are generally formed as steel bodied rams. The rams 18
are locked
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1 onto the ends of ram screws 20, which extend through end plugs or bonnets
22 at the
2 outer ends of the ram bores 14. The ram screws 20 can be turned to extend
or retract
3 the rams 18 into or out of the central bore 12 with mechanical screw
jacks (not shown).
4 The ram screw 20 is connected at the rear face 33 of the ram 18,
typically in a T-slot 35
(see Figure 4), in a manner known in the art. Alternatively, the ram screws 20
can be
6 extended and retracted with hydraulic actuators (not shown), as known in
the art. It
7 should be understood that the rams 18 may be alternately actuated, for
instance by
8 pneumatic or electrical actuators. Actuators may be single or double
acting, as known
9 in the art. Any of these mechanical screw jacks or alternate actuators
thus illustrate
actuators or ram actuating mechanisms for extending and retracting the rams 18
11 between their open position, in which the rams 18 are retracted from the
central bore
12 12, and the closed, sealing position, in which the opposing rams 18 are
extended to
13 seal around the polish rod P, and thus to seal the central bore from
pressure below.
14 It should be understood that one of the rams, along with the ram bores,
may be
adapted to include and accommodate an extended central bore sealing section as
16 described in U.S. Patent 7,552,765.
17 It should be understood that the ram bores 14 and corresponding rams 18
are
18 not necessarily strictly cylindrical in shape. The rams and bores may
take alternate
19 shapes, such as oval in cross section, as is known in the art.
A first embodiment of a ram 18 is shown in Figure 2. In Figure 1, this first
21 embodiment of a pair of rams 18 are shown in their fully extended,
sealing position, with
22 opposing front faces 32 (see Figure 2) sealed against each other,
against the polish rod
23 P, and against the central bore 12. The seal arrangement is one in which
the rams 18
24 carry seals adapted to seal the central bore 12 against pressure from
below. However,
it should understood that the rams 18 may be rotated or configured in a
different
26 manner. For example, a ram which is rotated 180 compared to Figure 1,
will seal the
27 central bore 12 against pressure from above. A ram which carries
additional mirror
16
CA 02777203 2012-05-16
1 image seals on the bottom portion of the ram, compared to Figures 1 and
2, will seal
2 the central bore 12 against pressure from above and below. Thus, while
embodiments
3 are described which seal against pressure from below, these are only
exemplary, and
4 not limiting, embodiments.
Each ram 18 includes a front end portion 24 (this being the portion which
6 extends into the central bore 12 in the extended position) and a rear end
portion 26
7 (facing the end plugs 22, and which remains within the horizontal ram
bore 14 in the
8 retracted and extended positions). The ram bores 14 are each of
sufficient length to
9 accommodate the ram 18 in its fully retracted, open position or its fully
extended,
sealing position.
11 Each ram 18 is formed from a steel body component 28 which is generally
12 cylindrical in shape for a tight fitting seal in the ram bore 14. The
body component 28
13 may be formed in multiple components which are assembled to form a
cylindrical ram,
14 but a single piece steel body component is shown in the Figures 1-22.
The ram 18 is formed with a vertical groove 30 that runs along the front face
32
16 of the ram 18 to accommodate the polish rod P or other tubular member.
In Figures 2,
17 3, 5, 6, 7 and 10, the vertical radial groove is shown as generally semi-
circular (in
18 horizontal cross section). The vertical groove 30 may be omitted if the
front ends of
19 the rams 17, 18 are to function as blind rams 70 to seal against each
other in the event
that the polish rod is not present, as shown in Figure 8. Still alternatively,
the vertical
21 groove may take the form of a vertical V-groove 34 running along the
front face 32, as
22 shown in Figure 9, and as described in US Patent No. 7,673,674. The V-
groove 34 is
23 sized to accommodate at least a portion of the circumference of the
polish rod within
24 the groove 34. In the V-groove embodiment of Figure 9, one or more
radial shaped,
raised backing sections 36 (two shown in Figure 9) are formed at sealing
locations
26 within the V-groove, these backing sections being sized to accommodate
the polish rod
27 P in a tight fitting relationship.
17
CA 02777203 2012-05-16
1 As shown in Figure 2, each of the rams 18 include at least one rope
packing
2 seal, shown as primary rope packing seal 40. The primary rope packing
seal 40 is
3 formed from a length of rope packing which forms a closed loop on the
outer surface of
4 the ram 18. The length of rope packing, and thus the primary rope packing
seal 40
extends horizontally across the front face 32 of the ram 18, including across
the vertical
6 groove 30, then generally rearwardly, and then upwardly around a portion
of the outer
7 surface of the ram 18 and over the top portion 44 of the ram 18. Although
not shown,
8 the primary rope packing seal 40 could alternatively, or in addition,
extend over the
9 bottom portion 45 of the ram 18. In order to seal the central bore 12,
the location where
the primary rope packing seal 40 extends over the top portion 44 (or bottom
portion 45)
11 is at a position on the ram 18 rearwardly of the front end portion 24,
such that the seal
12 40 at the top portion 44 remains within the ram bore 14 when the ram 18
is fully
13 extended (see Figure 1), so as to seal to the ram bore 14. In Figure 2,
the primary rope
14 packing seal 40 is shown to extend rearwardly along the side wall 42 of
the ram 18, and
then circumferentially upwardly across the top portion 44 of the ram 18.
Alternatively,
16 the primary rope packing seal could extend in an arcuate path, both
rearwardly and
17 upwardly, such as shown in Figure 10 (labeled as primary rope packing
seal 62, and
18 described below). Thus the terms "rearwardly", "upwardly" and
"downwardly" as used
19 herein and in the claims with respect to the rope packing seals are not
meant to refer to
strict horizontal or vertical orientations, but are meant to include arcuate
paths.
21 The primary rope packing seal 40 is preferably formed from a single
length of
22 rope packing. While multiple lengths could be used, a single length
minimizes the
23 number of joining ends to be accommodated, and thus minimizes weaknesses
in the
24 seal. The primary rope packing seal 40 is held within a continuous first
groove 46 (see
Figure 7) machined into the steel body component 28 to underlie the path of
the rope
26 packing seal 40. For the rams 18 shown in Figures 1-10, the continuous
first groove 46
27 is shown to be adapted to accommodate overlapping end portions 48
(overlapping
28 ends) of the length of rope packing material in a manner to form a
dynamic seal as the
29 BOP ram 18 is extended or retracted in the ram bore 14. The overlap is
shown in the
18
CA 02777203 2012-05-16
1 Figures to be positioned at the top portion 44 of the ram 18, such that
the overlapping
2 ends 48 are positioned side by side, and are directed generally
perpendicularly to the
3 longitudinal axis L of the ram 18 (see Figure 6). In this way, as the ram
18 is moved
4 longitudinally along its axis L, the overlapping end portions 48 are
compressed together
by the extending/retracting movement of the ram 18. This is preferable to
locating
6 overlapping end portions at a position such that they are parallel to the
longitudinal axis
7 of movement of the rams 18, since parallel overlapped ends may tend to be
pulled
8 apart by the extending/retracting movement of the ram 18. To accommodate
the
9 overlapping side by side end portions 48, the continuous first groove 46
is machined,
preferably at the top portion 44, with a widened groove portion 50 (see
Figures 4 and 7)
11 sized to accommodate two diameters of the overlapping ends 48 of the
rope packing
12 material in a compressed manner as the overlapping ends 48 lie side by
side. This side
13 by side overlapping ends 48 arrangement is shown within the widened
groove portion
14 50 in Figures 4 and 6.
Alternatively, a continuous first groove may be formed to accommodate joined
16 abutting ends of the rope packing. This is shown as a top view in the
embodiments of
17 rams 18a, 18b and 18c in Figures 11-13. In these Figures, the primary
rope packing
18 seal is shown at 40a, in a continuous first groove 46a (without a
widened portion), but
19 with the ends 48a of the rope packing being cut on a diagonal angle, for
example a 450
angle, at D such that they join (i.e., meet) with each other as joined
abutting ends 48a
21 within the groove 46a. As above, the joined abutting ends 48a are
preferably joined at
22 a location such that the ends are directed generally perpendicularly to,
or diagonally
23 across, the longitudinal axis of the ram. This minimizes pulling apart
action on the ends
24 48a as the ram 18a, 18b, 18c is extended and retracted in the ram bores
14.
The continuous first groove 46 is preferably sized with a depth dimension
which
26 is slightly undersized relative to the diameter or side dimension of the
rope packing.
27 The opening dimension of the continuous first groove 46 may also be
undersize relative
28 to the diameter or side dimension of the rope packing. Either or both of
these
19
CA 02777203 2012-05-16
1 techniques assist with the rope packing being held in the groove 46,
while protruding
2 radially from the groove 46, to provide the seal to sealing surfaces of
the housing 11. A
3 dove-tail shaped groove shape (see cross section of groove in Figure 4)
is particularly
4 preferred to hold and retain the rope packing against dislodging. The
groove 46 is best
illustrated in Figure 7, in which the rope packing seal 40 is removed. A "dove-
tail
6 shaped" groove is a groove which, in cross section, is sized smaller at
its opening
7 dimension than it is at the bottom wall dimension of the groove, for
example generally
8 trapezoidal shaped. However, other groove shapes such as generally round
or square
9 (in cross section) may be used. Rope packing materials are particularly
amenable to
being compressed into grooves of different shapes, so as to be retained
therein, while
11 also protruding therefrom.
12 As shown in Figure 2, the ram 18 may include a secondary rope packing
seal 52.
13 This secondary rope packing seal 52 has particular application in higher
pressure
14 sealing applications. The secondary rope packing seal 52 may be formed
from a
second single length of rope packing. The secondary rope packing seal 52
extends in a
16 continuous length, horizontally across the front face 32 of the ram 18,
including across
17 the vertical groove 30 (preferably parallel and below the primary rope
packing seal 40).
18 The rope packing seal 52 then extends rearwardly along the side wall 42
of the ram
19 body 28 (for example parallel and spaced below the primary rope packing
seal 40), and
upwardly to meet the primary rope packing seal 40. As shown in Figure 7 (rope
packing
21 seals 40, 52 removed), the secondary rope packing seal 52 is held within
a continuous
22 second groove 53 machined into the steel body component 28 to underlie
the
23 secondary rope packing seal. The second groove 53 is preferably
undersized in its
24 depth dimension, and preferably dove-tail shaped, as set forth above for
first groove 46
and/or 46a. At the point where the secondary rope packing seal 52 meets the
primary
26 rope packing seal 40, the grooves 53 and 46 are continuous with each
other (see
27 Figure 7).
28 Alternatively, the secondary rope packing seal may extend rearwardly
and then
CA 02777203 2012-05-16
1 upwardly (or downwardly), spaced from the primary rope packing seal, and
around the
2 top portion or bottom portion of the ram to form a closed loop. In such
embodiments, a
3 continuous second groove adapted to hold the secondary rope packing seal
is adapted
4 to accommodate joined or overlapping ends of the rope packing as set out
above for
the primary rope packing seal.
6 In the Figures, the primary rope packing seal 40 is shown to extend
rearwardly at
7 a location which is above the central portion 54 of the ram 18 (i.e,
above a central
8 horizontal cross section line through the ram), and then over the top
portion 44 of the
9 ram 18. In this manner, upward pressure along the central bore 12 assists
in sealing the
ram 18 in its extended sealing position, as the primary rope packing seal 40
is radially
11 compressed against the wall of the ram bores 14. The secondary rope
packing seal 52
12 (if present), may be located horizontally below the primary rope packing
seal 40, for
13 example at or near the central portion 54 of the ram 18 (i.e., closer to
a central
14 horizontal cross section line through the ram). However, other locations
of the rope
packing seals 40, 52 are possible. For instance, if a bidirectional BOP
sealing ram is
16 needed, the BOP ram may be formed with a primary rope packing seal 40
such as
17 shown in the Figures, located above the central portion 54 of the ram
18, and with a
18 further rope packing seal (not shown) located as a mirror image below
the central
19 portion of the ram 18.
It should be also be apparent that the rams 18 as shown in the Figures could
be
21 rotated for positioning in the ram bores 14 such that the rope packing
seals 40 and/or
22 52 are located below and at the central portion of the ram 18. Further,
the rams 18
23 might be modified to include an upper rope packing (such as primary rope
packing seal
24 40), a lower rope packing seal which may be a mirror image of the upper
rope packing
seal, and a central rope packing seal located horizontally between the upper
and lower
26 rope packing seals, and which extends upwardly and downwardly at its
sides to join
27 with the upper and lower rope packing seals.
21
CA 02777203 2012-05-16
1 The rear end portion 26 of the ram 18 may be formed with a
circumferential seal
2 56 to seal the ram bores 14. In some BOP embodiments the end plugs or
bonnet 22
3 may be used to seal the ends of the ram bores 14, so the circumferential
seal 56 may
4 be omitted in such embodiments. This circumferential seal 56 may be
formed from a
length of rope packing material to comprise a circumferential rope packing
seal 56. The
6 ram 18 may be formed with a continuous circumferential groove 58 at the
rear end
7 portion 26 to underlie the rope packing circumferential seal 56. The
circumferential
8 groove 58 may be formed to accommodate joined abutting ends 56a cut on a
diagonal
9 angle at E (not shown in Figures 1-10 or 13, but shown at the top portion
44 of ram 18a
in Figure 11). Alternatively, as shown in Figure 12 for ram 18b, the
circumferential
11 groove 58b may be formed with a widened portion 75 to accommodate
overlapped
12 ends 56b as described above for the primary rope packing seal 40. For
the
13 circumferential seal 56, the location of the widened portion or joined
abutting ends is
14 not critical, since the ends will be positioned perpendicular to the
longitudinal axis of
ram movement regardless of its location. In this way, the circumferential seal
56 also
16 functions as a dynamic seal.
17 Figure 10 illustrates alternate embodiment of a ram 60, in which the
primary rope
18 packing seal 62 extends horizontally across the front face 32, including
across the
19 vertical groove 30, and then extends rearwardly and upwardly along an
arcuate path to
meet at the top portion 44 of the ram 18, where overlapped end portions 63 are
21 accommodated as described above. Similarly, the secondary rope packing
seal 64
22 extends horizontally across the front face 32, including across the
vertical groove 30,
23 but spaced below the primary rope packing seal 62, and then extends
rearwardly and
24 upwardly along an arcuate path to meet the primary rope packing seal 62.
The rope
packings for these seals 62 and 64 are held in first, second grooves 66, 68
machined in
26 the body component 28, and positioned to underlie the seals 62, 64.
27 In the embodiment of Figure 8, the primary and secondary rope packing
seals
28 40, 52 are as described above, but being a blind ram 70, no vertical
groove is formed in
22
CA 02777203 2012-05-16
1 the front face of the ram 70.
2 In the embodiment of Figure 9, the primary and secondary seals 40, 52
are
3 generally as described above for Figure 2, but in a ram 72 formed with a
vertical V-
4 groove 34 to accommodate the polish rod P (not shown), the rope packing
seals 40, 52
are formed on the radial backing sections 36, with the first and second
grooves 46, 53
6 being machined horizontally across these backing sections 36. A
circumferential seal
7 56 is formed in the rear portion 26, as described above for Figure 2.
Other aspects of
8 the V-groove ram are more fully described in U.S. Patent No. 7,673,674.
9 The rope packing seals may be made from any known rope packing seal
materials. Rope packings are available in many different forms, for example,
braided,
11 twisted, woven and knitted. The rope packing may have a core material
which differs or
12 is the same as the outer sealing material in composition, for example
higher
13 temperature seal material may be used over a lower temperature core
materials. As
14 well, the rope packing may be reinforced, for example with wire
reinforcing materials
such as steel, copper or stainless steel. The cross sectional shape may vary,
such as
16 square, square with rounded corners, oval or circular, with square being
preferred. The
17 continuous groove in the rams can be varied to accommodate and hold
different cross
18 sectional shapes of rope packings. Examples of rope packings include
braided cotton
19 twill, braided ramie fibre, braided tallowed rayon, tallowed flax
graphite, braided jute
yarn, braided glass fibre, aluminum foil, braided copper wire, braided PTFE
materials
21 (polytetrafluoroethylene such as Teflon ), Teflon impregnated braided
asbestos,
22 braided ceramics, braided asbestos, and braided graphite. One exemplary
material for
23 very high temperature applications is graphite rope packing which is
stainless steel
24 reinforced, with a square cross section and a side dimension of about
0.8 cm.
Diameters of rope packing ranging from about 0.5 cm to 2 cm may be used. The
rope
26 packing is threaded or pressed into the machined grooves 46, 53, 58 for
example with a
27 hammer, or other known rope packing threading tools/devices.
23
CA 02777203 2012-05-16
1 Each of the primary and circumferential rope packing seals (and in
some
2 embodiments the secondary rope packing seal), by being formed from a
length of rope
3 packing arranged as a closed loop, and being held in a continuous groove
which
4 accommodates either joined abutting ends, or overlapping ends in side by
side
relationship, is able to provide a dynamic seal on a blowout preventer ram.
6 In general, rope packings have been previously used only as static
seals in the
7 wellhead equipment, where the seal remains generally static during seal
8 operation/energization. Examples of static rope packing seal applications
include
9 annular seals on rotating or translating pipes, shafts or stems (ex.
stuffing box seals), or
in place of 0-ring seals on tubulars such as tubing hangers. The BOPs and rams
11 described herein accommodate rope packings as a dynamic (moving) seal.
This
12 enables higher temperature rope packing materials to be used. For
instance, graphite
13 reinforced stainless steel rope packing materials have been rated up to
about 1000 F,
14 high enough for wellheads designed for steam injection or other very
high temperature
heating applications. Rope packing materials for very low temperature
applications
16 may also be accommodated.
17 In the embodiments shown in Figures 14-23, the rams are shown to be
18 configured with front faces to abut and press against each other in the
extended
19 position so as to impart a generally vertical movement to the opposing
rams.
Alternatively, or in addition, the BOP rams shown in Figures 14- 23 may be
configured
21 such that the seals across the front faces of the opposing rams have a
vertical offset so
22 that the front face seals seal against each other, but with this
vertical offset. The
23 multiple embodiments of Figures 1-23 are shown with like parts being
labeled with the
24 same reference numerals.
Having reference to Figure 14, a production blowout preventer (BOP) is shown
26 generally at 100, to include a cross-shaped, pressure-containing steel
housing 11
27 forming a central bore 12, extending generally vertically through the
housing 11, and a
24
CA 02777203 2012-05-16
1 pair of co-axial horizontal ram bores 14. The ram bores 14 are slightly
larger in
2 diameter than the central bore 12, as is common in BOP devices. Top and
bottom
3 flange connectors 15, 16 to wellhead components located above and below
the BOP
4 100 are shown, although alternate top and bottom connectors such as
mentioned
above may be used. The horizontal ram bores 14 intersect with the central bore
12.
6 The ram bores 14 are formed with a larger diameter than that of the
central bore 12,
7 and sealing surfaces are formed across the central bore at the
intersection of the bores
8 12, 14, all as is generally known in the art. The polish rod P is shown
in place in the
9 central bore 12. The polish rod P is an example of a tubular member which
may be
present in the central bore 12.
11 A pair of generally cylindrical BOP rams 118a, 118b are shown in Figure
14.
12 Each of the rams 118a, 118b may be formed in multiple parts, but are
generally
13 cylindrically shaped when assembled for close fitting relationship in,
and optionally for
14 sealing to, the ram bores 14. The rams 118a, 118b are generally formed
as steel
bodied rams, although one or more coatings may be formed on the rams or
portions of
16 the rams. The rams 118a, 118b are locked onto the ends of ram screws 20,
which
17 extend through end plugs or bonnets 22 at the outer ends of the ram
bores 14. The
18 ram screws 20 can be turned to extend or retract the rams 118 into or
out of the central
19 bore 12 with mechanical screw jacks which can operate on the external
ends of the ram
screws 20. Each ram screw 20 is connected at the rear face 133 of the ram
118a,
21 118b, typically in a T-slot 135 (see Figure 19), in a manner known in
the art. The ram
22 screws 20 can be extended and retracted with other types of ram
actuating
23 mechanisms as set out above. The ram screws 20, with the ram actuating
24 mechanisms, extend and retract the rams 118a, 118b between the open
position, in
which the rams 118a, 118b are retracted from the central bore 12, and the
closed,
26 sealing position, in which the opposing rams 118a, 118b are extended to
seal against
27 each other, around the polish rod P if present, upwardly against the ram
bores 14, and
28 across the sealing surfaces of the central bore 12 to seal the central
bore from pressure
29 below.
CA 02777203 2012-05-16
1 As above, one of the rams, along with the ram bores, may be adapted to
include
2 and accommodate an extended central bore sealing section as described in
U.S.
3 Patent 7,552,765. As well, the ram bores 14 and corresponding rams 118a,
118b are
4 not necessarily strictly cylindrical in shape. The rams and bores may
take alternate
shapes, such as oval in cross section, as is known in the art. As well, as
mentioned
6 above, the rams 118a, 118b, and the ram screws 20 may be rotated through
180 to
7 seal against pressure from above, in which case, the rams 118a, 118b seal
as above
8 for Figure 14, but downwardly against the ram bores 14 (instead of
upwardly as above).
9 As best shown in Figure 15, on the right hand ram body 118a of Figure
14, but
also applying with general mirror symmetry to left hand ram body 118b, the ram
118a
11 includes a front end portion 124 (this being the portion which extends
into the central
12 bore 12 in the extended position) and a rear end portion 126 (facing the
end plugs 22,
13 and which remains within the horizontal ram bore 14 in the retracted and
extended
14 positions). The ram bores 14 are each of sufficient length to
accommodate the ram
118a (or 118b) in its fully retracted, open position or its fully extended,
sealing position.
16 Each ram 118a, 118b is formed from a steel body component 128 which is
17 generally cylindrical in shape for a tight fitting seal in the ram bore
14. The body
18 component 128 may be formed in multiple components, as in Figure 23
which are
19 assembled to form a cylindrical full body ram, but a single piece steel
body component
is shown in the Figures 14-22.
21 The ram 118a,118b may be formed with a vertical groove 130 that runs
along the
22 front face 132 of the ram 118b, 118b to accommodate the polish rod P or
other tubular
23 member. In Figures 17, 18 and 22 the vertical radial groove is shown as
generally
24 semi-circular (in horizontal cross section). The vertical groove 130 may
be omitted if
the front ends of the rams 118a, 118b are to function as blind rams 170 to
seal against
26 each other in the event that the polish rod P is not present, as shown
in Figure 21. Still
27 alternatively, the vertical groove may take the form of a vertical V-
groove 134 running
26
CA 02777203 2012-05-16
1 along the front face 132, as shown in the ram 172 of Figure 20, and as
described in
2 greater detail in US Patent No. 7,673,674. The V-groove 134 is sized to
accommodate
3 at least a portion of the circumference of the polish rod P within the
groove 134. In the
4 V-groove embodiment of Figure 20, one or more radial shaped, raised
backing sections
136 (two shown in Figure 20, one for each seal) are formed at sealing
locations within
6 the V-groove 134. These backing sections 136 being sized to accommodate
the polish
7 rod P in a tight fitting relationship in order to seal to the polish rod
P.
8 In Figure 14, the pair of rams 118a, 118b are shown being moved into
the
9 extended position, but not yet in the fully extended, sealing position.
As shown in
Figure 14, and also in Figure 15, the front face 132 of each of the rams 118a,
118b is
11 formed with mirror symmetry, with a leading edge portion 175 adapted to
first abut or
12 first contact the leading edge portion 175 of the opposing ram 118a,
118b in advance of
13 the remainder of the front face 132 of the opposing ram 118a, 118b. In
this way, the
14 leading edge portions 175 of the opposing rams 118a, 118b abut and are
then pressed
against each other as the rams 118a, 118 b continue to be moved into the
extended
16 position by the ram screws 20. This continued pressing against each
other of the
17 leading edge portions 175 imparts a generally vertical movement to the
opposing ram
18 118a, 118b. In the embodiments of Figures 14-23, the generally vertical
movement is
19 generally upwardly, however, if the rams were rotated 180 , the
generally vertical
movement is generally downwardly. The generally vertical movement may also be
21 envisaged as a generally upward or downward rotating movement as the
rams move
22 through an angle relative to the center axis of the rams bores C.
23 As shown in Figures 14 and 15, each of the rams 118a, 118b include at
least
24 one seal, shown as a primary rope packing seal 140. This seal 140 could
alternatively
be formed of an elastomeric or thermoplastic material, although the rope
packing seal
26 materials may be selected for very high or very low temperature
environments in which
27 the elastomeric or thermoplastic seal materials may not function as
well, or at all. The
28 primary rope packing seal 140 is formed from a length of rope packing
which forms a
27
CA 02777203 2012-05-16
1 closed loop on the outer surface of the ram 118a, 118b. The length of
rope packing,
2 and thus the primary rope packing seal 140 extends horizontally across
the front face
3 132 of the ram 118a, 118b, including across the vertical groove 130, then
generally
4 rearwardly, and then upwardly around a portion of the outer surface of
the ram 118a,
118b and over the top portion 144 of the ram 118a, 118b. Although not shown,
the
6 primary rope packing seal 140 could alternatively, extend over the bottom
portion 145 of
7 the ram 118a, 118b. In order to seal the central bore 12, the location at
which the
8 primary rope packing seal 140 extends over the top portion 144 (or bottom
portion 145)
9 is at a position on the ram 118a, 118b rearwardly of the front end
portion 124, such that
the seal 140 at the top portion 144 remains within the ram bore 14 when the
ram 118a,
11 118b is fully extended so as to seal to the ram bore 14. Figure 14 shows
the seal 140
12 at the top portion 144 as being located within the ram bores 14, and
thus rearwardly of
13 the front end portion 124. In Figures 14 and 15, the primary rope
packing seal 140 is
14 shown to extend rearwardly along the side wall 142 of the ram 118a,
118b, and then
circumferentially upwardly over the top portion 144. Alternatively, the
primary rope
16 packing seal could extend in an arcuate path, both rearwardly and
upwardly, such as
17 shown in Figure 22 (labeled as primary rope packing seal 162 on ram
173). Thus the
18 terms "rearwardly", "upwardly" and "downwardly" as used herein and in
the claims with
19 respect to the rope packing seals are not meant to refer to strict
horizontal or vertical
orientations, but are meant to include arcuate paths.
21
22 As shown in Figures 14 and 15, the leading edge portions 175 are
located above
23 the primary rope packing seal 140, adjacent the top portion 144 of the
ram 118a, 118b.
24 When the generally vertical movement is imparted to the rams 118a, 118b
as they are
moved into the extended position, the seals 140 on the front faces 132 are
brought into
26 sealing engagement with each other, and the seal 140 extending over the
top portion
27 144 of the ram 118a, 118b is energized as the ram is moved upwardly
against the ram
28 bore 14. In an embodiment in which the rams 118a, 118b are rotated 180
compared
29 to Figure 14, the leading edge portions may be located below the seal
140, and the
generally downward movement imparted in the extended position energizes the
seal
28
CA 02777203 2012-05-16
1 140 downwardly against the ram bore 14.
2 In the embodiment shown in Figures 14 and 15, the front faces 132 of
the rams
3 118a, 118b are formed with an inclined portion 177 such that a plane
through the
4 inclined portion 177 is inclined toward the central bore 12, and in a
manner such that
the inclined portions 177 on opposing rams 118a, 118b are brought into contact
with
6 each other by the generally vertical movement imparted to the opposing
rams 118a,
7 118b. The seal 140 may be located on the inclined portion 177, so that as
the inclined
8 portions 177 on opposing rams 118a, 118b are brought into contact with
each other, the
9 seals 140 are energized against each other, and against the polish rod P,
if present.
In the embodiment of Figures 14 and 15, the leading edge portion 175 is
located
11 adjacent the top portion 144, and the front face 132 of the ram 118a,
118b forms one
12 inclined portion, such that a plane through the front face 132 is
inclined top to bottom
13 toward the central bore 12. In this embodiment, the inclined portions
177 are shown to
14 leave a horizontal gap 179 between the bottom portions 145 when the rams
reach the
position across the central bore when the leading edge portions 175 of the
opposing
16 rams 118a, 118b first contact (see Figure 14 for gap 179). This gap 179
is sized to
17 close as the rams 118a, 118b are moved into the fully extended, sealing
position. In
18 general, the gap 179 is sized by an angle formed between a plane through
the inclined
19 portion 177 and a vertical plane through the central axis of the central
bore 12. This
angle will vary with the size of the BOP and the BOP rams, but is generally
less than 10
21 degrees, such as less than 5 degrees, such as between about 1 and 3
degrees, and
22 such as between about 2 and 3 degrees. In embodiments in which the rams
are
23 rotated 180 compared to Figure 14, this gap 179 will be present at the
top of the rams.
24 As best shown in Figure 14, to facilitate imparting the generally
vertical
movement to the ram 118a, 118b, each of the ram screws 20 is connected to the
rear
26 face 133 of the rear end portion 126 of the ram 118a, 118b at a point
below a the
27 center axis C of the ram bores 14 (which is also below the longitudinal
axis L of the
29
CA 02777203 2012-05-16
1 rams 118a, 118b). In Figure 14, the ram screw center line S is shown to
be below
2 center axis C and longitudinal axis L. With this feature, as the rams
screw 20 pushes
3 on the rear end portion 126, the off center force (below the center in
Figure 14)
4 facilitates an upward rotation of the ram 118a, 118b, and thus
facilitates the generally
upward movement of the ram to assist in the sealing actions for the seal 140
described
6 above. In alternate embodiments, in which the ram 118a, 118b is rotated
180 the ram
7 screw 20 may be connected above the center axis of the ram bore 14 to
facilitate a
8 downward movement of the ram.
9 To further facilitate imparting the general vertical movement to the
ram 118a,
118b, and to allow the ram to flex in the ram bore 14, the front face of the
ram 118a,
11 118b is formed with a cut away portion 182 located above or below the
seal 140. In
12 Figures 14 - 22, the cut away portion 182 is shown as a horizontal slot
184 below the
13 seal 140, extending across the front face 132 and rearwardly in the ram.
In an alternate
14 embodiment in which the rams are rotated through 180 compared to Figure
14, the cut
away portion 182 could be located above the seal. In Figures 14-22, the
horizontal slot
16 184 is shown to extend rearwardly of the front end portion 124 of the
ram to provide a
17 significant flex movement to the ram. However, in alternate embodiments,
depending
18 on the size of the rams and the size of the front end gap 179, and thus
the rigidity of the
19 steel bodied ram, the horizontal slot may extend rearwardly to a greater
or lesser extent
to provide the desired amount of flex to initiate the vertical movement and
sealing
21 actions of the rams. As an alternative to the horizontal slot, the cut
away portion 182
22 may remove a portion of the ram extending across the entire front face
132 at a location
23 above or below the seal (below the seal when configured as in Figure
14).
24 In an alternate embodiment shown in Figure 16, the leading edge portion
175 is
formed on the ram 171 (and on an opposing ram formed with general mirror
symmetry)
26 as a flattened planar portion 180. The flattened planar portion 180 may
be formed
27 adjacent the top portion 144 of the ram 171. A plane through the
flattened planar
28 portion 180 is generally vertical. By forming the leading edge portion
175 as a flattened
CA 02777203 2012-05-16
1 planar portion 180, the ram 171 has more planar surface area over with to
abut the
2 flattened planar portion of the opposing ram at the point of first
contact, and to press
3 against the flattened planar portion of the opposing ram in order to
impart the generally
4 vertical (upward for ram 171) movement to the ram 171. In Figure 16, the
ram 171 is
formed with the inclined portion 177 located directly below the leading edge
portion 175,
6 and inclined from the leading edge portion to the bottom portion toward
the central
7 bore. As noted above for the ram 118a, the ram 171 may be rotated 180
for sealing
8 downwardly in alternate embodiments.
9 The leading edge portions 175 and the inclined portions 177 may be
alternately
configured than as shown in the figures, provided the leading edge portion 175
is the
11 point of first contact with the opposing rams (apart from any protruding
seals), and
12 provided these portions and any other surfaces at the front face 132
allow for the
13 generally vertical movement and sealing actions of the ram, as above-
described, in the
14 extended position.
As described above, the rams 118a, 118b may be formed with a primary rope
16 packing seal 140. In Figures 14 - 21, the primary rope packing seal 140
is configured
17 similarly to the embodiment shown in Figures 1-2, formed from a single
length of rope
18 packing material held in a continuous first groove 146 (see Figure 17,
with the rope
19 packing seals removed) and having overlapping end portions 148 held in
side by side
relationship at the top portion 144 of the ram in a widened groove 150. In
Figure 22,
21 the primary rope packing seal 162 is configured similarly to the
embodiment shown in
22 Figure 10 in which the primary rope packing seal 162 follows a generally
arcuate path in
23 the continuous first groove 166, over the top portion 144 such that the
overlapping end
24 portions 163 are accommodated in a widened portion of the continuous
first groove
166, as described above.
26 A secondary rope packing seal 152 may be included, as shown in Figures
14-22.
27 In Figures 14-21, the secondary rope packing seal 152 is configured
similarly to the
31
CA 02777203 2012-05-16
1 embodiment of Figures 1-2, except that the ends 152a of second length of
rope packing
2 meet the primary rope packing seal 140 at the side wall 142 of the ram
with overlap
3 between the primary and secondary rope packing seals 140, 152. The
secondary rope
4 packing seal 152 extends horizontally across the front face 132,
including across any
vertical groove 130, preferably parallel and spaced below the primary rope
packing seal
6 140, held within a second groove 153 (see Figure 17 with the rope packing
seals
7 removed). The secondary rope packing seal 152, within second groove 153
extends
8 rearwardly along the side wall 142 of the ram, generally spaced from and
below the
9 primary rope packing seal 140, and then upwardly to meet the primary rope
packing
seal 140. In Figure 22, the secondary rope packing seal 164 is similar to the
11 embodiment shown in Figure 10, with the secondary rope packing seal 164
following a
12 generally arcuate path in the second groove 168 to meet the primary rope
packing seal
13 162 at the side wall 142.
14 As with the embodiments of Figures 1-13, the first and second grooves
may be
dove-tail shaped in cross section to retain the first and second lengths or
loops of rope
16 packing.
17 As best shown in Figure 14, in order to limit a pulling action of the
primary rope
18 packing seals 140 at the front face 132 of the ram 118a, 118b as the
seals 140
19 disengage from each other after sealing against each other, a vertical
offset between
the seals 140 on opposing rams 118a, 188b may be added. As shown in Figure 14,
the
21 primary rope packing seal 140 on ram 118a is located with a vertical
offset relative to
22 the primary rope packing seal 140 on the opposing ram 118b, such that
the seal 140 on
23 ram 118a is located slightly vertically lower on the front face 132 than
is the seal 140 on
24 opposing ram 118b. However, the seals 140 on the opposing rams 118a,
118b still
overlap slightly so that they may still seal against each other in the
extended position,
26 but they seal against each other with the vertical offset. In this
manner, as the rams
27 118a, 118b are retracted from the extended sealing position, the seals
140 are less
28 likely to pull each other out of the underlying first grooves 146.
32
CA 02777203 2012-05-16
1 Similarly, the secondary packing seals 152 are positioned across the
front face
2 132 of the ram 118a with a similar vertical offset relative to the
secondary rope packing
3 seal 152 on the front face 132 of the opposing ram 118b, such that in the
extended
4 position, the secondary rope packing seals 152 on the opposing rams 118a,
118b seal
against each other but with the vertical offset.
6 This vertical offset feature of the front face seals 140, 152 is a
feature for which
7 the opposing rams 118a, 118b do not share mirror symmetry. However, as is
apparent
8 from the Figures 14-23, and from the description of the embodiments of
Figures 14-23
9 herein, other features of the opposing rams are formed with mirror
symmetry, including
the leading edge portions, the inclined portions, the cut-away portions and
the ram
11 screws off-center connections.
12 Other embodiments of the primary and secondary rope packing seals, and
the
13 optional inclusion of a circumferential rope packing seal located
rearwardly of the first
14 and second rope packing seals, may be included, as set out above for the
embodiments of Figures 1-13. Any of the primary, secondary and circumferential
rope
16 packing seals may be formed from a continuous loop of rope packing
material, in which
17 case overlapping or adjoining two ends of the lengths of rope packing do
not need to be
18 accommodated, and a continuous groove may be used to hold each loop of
rope
19 packing.
In the embodiment shown in Figure 23, a production BOP ram 200 is shown
21 generally configured to be positioned in the ram bores 14 of a BOP
housing 11 such as
22 shown in Figure 14. In the description herein, the ram 200 is described
as if positioned
23 in the BOP housing 11 of Figure 14, with like parts being labeled with
the same
24 reference numbers. The ram 200 has a front end portion 202, a rear end
portion 204, a
top portion 206, a bottom portion 208 and side walls 209. In an extended
position, the
26 front end portion 202 extends across the central bore 12 and the rear
end portion 204 is
27 within the ram bore 14. In a retracted position, the ram 200 is within
the ram bore 14.
33
CA 02777203 2012-05-16
1 The ram 200 is shown to consist of a steel body component 210 forming the
bottom
2 portion 208 of the ram 200, and a steel seal component 212 forming the
top portion 206
3 of the ram 200. When assembled, the body component 210 and the seal
component
4 212 form a full body ram. Each of the opposing rams 200 is formed
generally with
mirror symmetry to each other, and are each generally cylindrical in shape for
a tight
6 fitting seal in the ram bore 14. The body component 210 has a front
portion 214, a rear
7 portion 216, a front end 218 and a rear end 220. The seal component 212
has a front
8 portion 222, a rear portion 224, a front end 226, a rear end 228 and a
front face 230.
9 The seal component 212 is shaped to fit into a cut-out 232 formed at
the front
portion 214 of the body component 210. The cut-out 232 provides a seal support
11 surface 234 to support the seal component 212 in both a vertical and
horizontal
12 direction. The cut-out 232 may be generally L-shaped, as shown. However,
similarly to
13 that described in U.S. Patent 7,137,610, the cut-out portion may have an
alternate
14 shape, such as a wedge shape. The rear end 216 of the body component 210
is
formed with a central T-slot 236 to connect and lock onto the end of the ram
screws 20,
16 such as shown in Figure 14.
17 The seal component 212 includes a primary rope packing seal 238 formed
18 entirely on the outer surface of the seal component 212. The primary
rope packing seal
19 238 extends across the front face 230 of the seal component 212,
rearwardly and then
upwardly over the top portion 206 of the ram 200 at a position rearwardly of
the front
21 end portion 202 of the ram 200. As with the embodiments of Figures 14-
23, the primary
22 rope packing seal 238 is formed from a first length or loop of rope
packing, and is held
23 within a continuous first groove 240 formed similar to the continuous
first groove in the
24 embodiments described hereinabove.
As set out above for the embodiments of Figure 14, the primary rope packing
26 seal 238 may be positioned across the front face 230 of the seal
component 212 with a
27 vertical offset relative to the primary rope packing seal 238 on the
front face 230 of the
34
CA 02777203 2012-05-16
1 seal component 212 of the opposing ram 200, such that in the extended
position, the
2 primary rope packing seals 238 on the opposing rams 200 seal against each
other but
3 with the vertical offset.
4 A secondary rope packing seal 239 may be included on the seal component
212
similar to that shown in Figures 14-22. The secondary rope packing seal 239
extends
6 horizontally across the front face 230 of the seal component 212,
including across any
7 vertical groove which may be present, preferably parallel and spaced
below the primary
8 rope packing seal 238, and held within a second groove 241. The secondary
rope
9 packing seal 239, within second groove 241 extends rearwardly along the
side walls
209 of the ram 200, generally spaced from and below the primary rope packing
seal
11 238, and then upwardly to meet the primary rope packing seal 238.
12 Similarly to above described embodiments, the secondary packing seal
239 may
13 be positioned across the front face 230 of the seal component 212 with a
vertical offset
14 relative to the secondary rope packing seal 239 on the opposing ram 200,
such that in
the extended position, the secondary rope packing seals 239 on the opposing
rams 200
16 seal against each other but with the vertical offset. As mentioned above
for the
17 embodiment of Figure 14, this vertical offset feature will generally be
a feature for which
18 the opposing rams 200 do not share mirror symmetry.
19 Each of the body and seal components 210, 212 are formed with a pair of
aligned horizontal pin bores 242, 244 respectively, to accommodate a pair of
side by
21 side connecting pins 246. Both the pin bores 242, 244 and one of the
connecting pins
22 246 are shown in dotted outline in the side view of Figure 23. One
design of the
23 connecting pins 246 is shown in Figure 23, but alternate embodiments are
described in
24 U.S. Patent 7,137,610.
Each of the body and seal components 210, 212 may be formed with a vertical
26 radial groove 247 that runs along the front of the assembled ram 200 to
accommodate
CA 02777203 2012-05-16
1 and seal against the polish rod P, if present. The vertical radial groove
247 may be
2 omitted if the front ends of the rams 200 are to function as blind rams
to seal against
3 each other in the event that the polish rod is not present. As shown, in
its assembled
4 and connected form with the body component 210, the front end 226 of the
seal
component 212 protrudes beyond the front end 218 of the body component 210 by
a
6 horizontal distance "d". This protruding front end 226 of the seal
component 212 acts
7 as a leading edge portion of the ram 200, similar to the leading edge
portion 175
8 described above for the embodiments of Figures 14-22.
9 The seal component 212 is generally semi-cylindrical in shape such
that, when
connected to the body component 210, the ram 200 is a full bore ram,
conforming to
11 the horizontal ram bores 14. In the embodiment shown, the seal component
212
12 includes the primary rope packing seal 238 at its outer circumference.
As more fully
13 explained below, when the rams 200 are advanced into the extended
position against
14 the polish rod P, the primary rope packing seal 238 encircles the
central bore 12 and
thus functions to seal the central bore 12 when the opposing rams 200 are
fully
16 engaged against the polish rod P.
17 The L-shaped cut-out 232 of the body component 210 is formed with a
slightly
18 inclined (front to rear), acutely angled seal support surface 234. A
similarly angled
19 lower surface 250 is formed on the seal component 212, such that in the
extended
position, the seal component 212 rides upwardly and rearwardly on the seal
support
21 surface 234 of the body component 210, as the rams 200 are moved into
the extended,
22 sealing position to close the central bore 12. In its assembled,
connected state, when
23 not in the extended position, the seal component 212 is seated in the L-
shaped cut-out
24 232, and a gap 252 remains at the rear end 228 of the seal component 212
between
the components 210, 212. The horizontal distance "d" by which the front end
226 of the
26 seal component 212 protrudes beyond the body component 210 is slightly
greater than
27 the horizontal width of the gap 252, to ensure a sealing action to the
polish rod P.
36
CA 02777203 2012-05-16
1 In the extended position the opposing rams 200 seal against each other,
against
2 the polish rod P, and outwardly against the horizontal ram bores 14 and
the sealing
3 surfaces of the central bore 12 to effectively seal the central bore 12
of the BOP
4 housing 11 against pressure from below. As the rams 200 are initially
advanced in the
ram bores 14, the protruding front ends 226 of the seal components 212 meet
each
6 other around the polish rod P, causing the seal components 212 to ride
upwardly and
7 rearwardly on the acutely angled seal support surfaces 234 of the body
components
8 210, until the gaps 252 between the seal and body components 212, 210 are
closed,
9 and the primary rope packing seals 238 on the seal components 212 are
pressed
against each other to seal the front faces 230 of the seal components 212 and
to seal
11 around the polish rod P. As well, the rearward and upward movement of
the seal
12 component 212 on the seal support surface 234 of the body component 210
moves the
13 primary rope packing seal 238 located at the top portion 206 of the ram
200 upwardly to
14 seal against the ram bore 14. The primary rope packing seal 238 also
seals against the
sealing surfaces of the central bore 12.
16 Alternate embodiments of the seal and body components will be apparent
to one
17 skilled in the art from the embodiments described in U.S. Patent
7,137,610, and such
18 embodiments fall within the claims of this application.
19 The rams 200 described herein include the seal component 212 above the
body
component 210. However, it should be apparent that the rams 200 could be
rotated
21 such that the seal component 212 is on the bottom. Further, the body and
seal
22 components 210, 212 may be modified such that both top and bottom seal
components
23 are carried on a more generally T-shaped body component to form the
cylindrical rams.
24 Furthermore, the components 210, 212 could be oval shaped rather than
strictly
cylindrical. Furthermore, the body component 210 could be two piece if
desired. These
26 and other modifications will be apparent to persons skilled in the art,
and are intended
27 to fall within the scope of the present invention.
37
CA 02777203 2012-05-16
1 The embodiments of the BOP as described above and/or the BOP rams
2 described above may be adapted to be included in a composite wellhead
assembly
3 including, between a top connector and a bottom connector, together with
one or more
4 of the following components, in any sequence, adapters, valves, gate
valves, flow tee,
additional blowout preventers, and polish rod clamp. To that end, attention is
directed
6 to the devices disclosed in the following U.S. Patents, all of which are
commonly owned
7 by Stream-Flo Industries Ltd.: U.S. 5,743,332, issued April 28, 1998,
entitled "Integral
8 Wellhead Assembly for Pumping Wells"; U.S. 6,457,530, issued October 1,
2002,
9 entitled "Wellhead Production Pumping Tree"; U.S. 6,176,466, issued
January 23,
2001, entitled "Composite Pumping Tree with Integral Shut-Off Valve"; and U.S.
11 6,595,278, issued July 22, 2003, entitled "Assembly for Locking a
Polished Rod in a
12 Pumping Wellhead". Each of these patents discloses wellhead equipment
used in
13 connection with pumping oil wells, but in a composite form, meaning that
one or more
14 functional components of a conventional pumping tree are included in an
integral body
housing between a top and a bottom connector. Such components may include a
shut
16 off valve, a blowout preventer, a flow tee and an adapter. As a
composite wellhead,
17 the components are included in an integral tubular body formed from a
single piece of
18 steel, and forming an axial, vertical or central fluid flow bore
extending therethrough.
19 Multiple side openings are formed in the body, each communicating with
the vertical
bore, in order to house the valve, BOP and flow tee components. The body
includes a
21 bottom connector for connection with a wellhead component located
therebelow, for
22 example a flanged top connection of a tubing head. This bottom
connection might be a
23 studded down connection, or any other bottom connector such as a flanged
connection,
24 clamp-hub connection, rotatable flange connection, welded connection or
threaded
connection. The body may include a valve housing section above the bottom
26 connection to house a conventional gate valve assembly operative to open
or close the
27 central bore. Above the valve housing section may be a first BOP housing
section,
28 adapted to house the ram assembly components of one or more of the
Figures
29 described above. A second BOP housing section may optionally be formed
in the body
above the first BOP housing section, housing same or different ram or polish
rod clamp
38
CA 02777203 2012-05-16
1 components as described above. Above the second BOP housing is typically
a flow tee
2 housing section for connection with a conventional flow line, through
which well fluid is
3 produced. The body forms a top connector at its upper end for connection
with the
4 wellhead component located thereabove, typically a stuffing box. The top
connector
may include studded connectors, but any other type of connector as indicated
above for
6 the bottom connector, may be substituted, as known in the art. As
indicated, this is only
7 one exemplary composite wellhead assembly. The components may be provided
in
8 different sequences, and may be varied, added or omitted as is
appropriate for the
9 needs of a particular wellhead.
All references mentioned in this specification are indicative of the level of
skill in
11 the art of this invention. If any inconsistency arises between a cited
reference and the
12 present disclosure, the present disclosure takes precedence. Some
references provide
13 details concerning the state of the art prior to the filing of this
application, other
14 references may be cited to provide additional or alternative device
elements, additional
or alternative materials, additional or alternative methods of analysis or
application of
16 the invention.
17 The terms and expressions used are, unless otherwise defined herein,
used as
18 terms of description and not limitation. There is no intention, in using
such terms and
19 expressions, of excluding equivalents of the features illustrated and
described, it being
recognized that the scope of the invention is defined and limited only by the
claims
21 which follow. Although the description herein contains many specifics,
these should not
22 be construed as limiting the scope of the invention, but as merely
providing illustrations
23 of some of the embodiments of the invention.
24 One of ordinary skill in the art will appreciate that elements and
materials other
than those specifically exemplified can be employed in the practice of the
invention
26 without resort to undue experimentation. All art-known functional
equivalents, of any
27 such elements and materials are intended to be included in this
invention. The invention
39
CA 02777203 2012-05-16
1 illustratively described herein suitably may be practiced in the absence
of any element
2 or elements, limitation or limitations which is not specifically
disclosed herein.
