U.S. patent number 3,572,627 [Application Number 04/765,061] was granted by the patent office on 1971-03-30 for blowout preventer.
This patent grant is currently assigned to Cameron Iron Works, Inc.. Invention is credited to Benton Baugh, Marvin R. Jones.
United States Patent |
3,572,627 |
Jones , et al. |
March 30, 1971 |
BLOWOUT PREVENTER
Abstract
An annular blowout preventer comprising a housing having a bore
through it and an annular recess extending outwardly from the bore,
and a packer within the recess including an annulus of deformable
material having a bore aligned with the housing bore and a circular
series of rigid inserts extending therethrough from one end to the
other. A sealing surface on an end portion of the annulus engages
the oppositely facing end surface of the recess, and there are
radially movable parts about the outer side of the annulus for
constricting the packer to urge its bore into position to seal
about a member in the bore of the housing or upon itself when the
bore is empty. The packer is symmetrical end-for-end so that it may
be disposed with either end up, and each of the rigid inserts
includes a rib having a flange at each end. The flanges are skewed
in the unconstricted position of the annulus and are caused to
swing into more radial positions as the annulus is constricted. The
sides of the flanges are adjacent one another to confine the
annulus at its opposite ends and cause the inserts to move in
unison, and the radially innermost ends of the flanges are
substantially adjacent the bore of the annulus when unconstricted,
so as to be moved into a position within the bore of the preventer
housing as the annulus is constricted.
Inventors: |
Jones; Marvin R. (Houston,
TX), Baugh; Benton; F. (Houston, TX) |
Assignee: |
Cameron Iron Works, Inc.
(TX)
|
Family
ID: |
25072531 |
Appl.
No.: |
04/765,061 |
Filed: |
October 4, 1968 |
Current U.S.
Class: |
251/1.2;
277/324 |
Current CPC
Class: |
E21B
33/06 (20130101) |
Current International
Class: |
E21B
33/06 (20060101); E21B 33/03 (20060101); E21b
033/06 () |
Field of
Search: |
;251/4,5,7,9,212
;166/81,82,84,86,88 ;277/34,73,127,129,185,235 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Dea; William F.
Assistant Examiner: Gerard; Richard
Claims
We claim:
1. A packer for use in an annular blowout preventer, comprising an
annulus of deformable material having a bore therethrough, and a
substantially circular series of rigid plates which are responsive
to movement of said material and which are arranged on at least one
end of the annulus with their end surfaces generally perpendicular
to the bore and their radially innermost ends substantially
adjacent the bore, when the annulus is unconstricted, to cause
their effective radial lengths to increase as the annulus is
constricted and said end surfaces to move radially inwardly of the
bore along a path generally perpendicular thereto.
2. A packer of the character defined in claim 1, wherein the plates
are arranged on each end of the annulus and ribs extend through the
annulus each to connect a pair of plates.
3. A packer for use in an annular blowout preventer, comprising an
annulus of deformable material having a bore therethrough, and a
substantially circular series of rigid plates on at least one end
of the annulus, the radially innermost ends of the plates being
substantially adjacent the bore, when the annulus is unconstricted,
and the plates being responsive to movement of said material and
arranged with their end surfaces generally perpendicular to the
bore so as to swing from skewed to more radially disposed positions
with respect to said bore as the annulus is constricted.
4. A packer of the character defined in claim 3, wherein the plates
are arranged on each end of the annulus and ribs extend through the
annulus each to connect a pair of plates.
5. A packer of the character defined in claim 3, wherein the sides
of the plates converge toward the bore of the annulus.
6. A packer of the character defined in claim 5, wherein the sides
of the plates are adjacent one another to confine the annulus and
cause the plates to swing in unison.
7. A packer of the character defined in claim 6, wherein the plates
are arranged on each end of the annulus and ribs extend through the
annulus each to connect a pair of plates.
8. A packer for use in an annular blowout preventer, comprising an
annulus of deformable material, and a substantially circular series
of rigid plates on at least one end of the annulus, the radially
innermost ends of the plates being substantially adjacent the bore
of the annulus, when the annulus is unconstricted, and a plane
bisecting each plate extending at an acute angle with respect to a
radius of the annulus which extends through the centroid of the
plate, when the annulus is unconstricted, said plate being
responsive to movement of said material so that, as said annulus is
constricted, said bisecting plane is swung toward said radius to
reduce the acute angle therebetween to thereby increase the
effective radial extent of each plate.
9. A packer of the character defined in claim 8, wherein the plates
are arranged on each end of the annulus and ribs extend through the
annulus each to connect a pair of plates.
10. A packer of the character defined in claim 8, wherein the sides
of the plates converge toward the bore of the annulus.
11. A packer of the character defined in claim 10, wherein each
side of each plate engages a side of an adjacent plate so as to
confine the annulus and prevent any one plate from moving
independently of the remainder during constriction of the
packer.
12. A packer of the character defined in claim 11, wherein the
plates are arranged on each end of the annulus and ribs extend
through the annulus each to connect a pair of plates.
13. An annular blowout preventer, comprising a housing having a
bore therethrough and an annular recess in the bore, and a packer
comprising an annulus of resilient material within the recess and
having a bore therethrough substantially aligned with the bore of
the housing, when the annulus is unconstricted, and a substantially
circular series of rigid plates on at least one end of the annulus
having end surfaces slidable over an adjacent end surface of the
annular recess in the housing, said adjacent surfaces of the plates
and recess being generally transverse to the aligned bores of the
housing and annulus, and said plates being responsive to movement
of said material so as to cause the radially innermost ends of the
plates to move inwardly into the bore of the housing and increase
in effective radial lengths as the annulus is constricted.
14. An annular blowout preventer of the character defined in claim
13, wherein the plates are arranged on each end of the annulus and
ribs extend through the annulus each to connect a pair of
plates.
15. An annular blowout preventer of the character defined in claim
13, wherein the plates are arranged to swing from skewed to more
radially disposed positions with respect to the bore as the annulus
is restricted.
16. An annular blowout preventer of the character defined in claim
15, wherein the sides of the plates are adjacent one another to
confine the annulus and cause the plates to swing in unison.
17. An annular blowout preventer of the character defined in claim
16, wherein the plates are arranged on each end of the annulus and
ribs extend through the annulus each to connect a pair of plates.
Description
This invention relates generally to blowout preventers and, more
particularly, to improvements in annular blowout preventers.
As well known in the art, a blowout preventer controls the pressure
within an oil or gas well during drilling and completion of the
well. It comprises a housing adapted to be connected above the head
of the well with its bore aligned with the well bore, and one or
more packing elements carried within a recess in the bore. The
packing element or elements are adapted to be moved inwardly for
closing about a pipe or other member in the bore or for closing the
entire bore when it is empty.
An annular blowout preventer has a single packer comprising an
annulus of rubber whose bore is adapted to be radially constricted.
In one such annular blowout preventer, shown and described in U.S.
Pat. No. 2,609,836, the packer comprises a massive annulus of
rubber having rigid inserts molded into it for containing it during
construction. These inserts extend from one end to the other of the
annulus and comprise longitudinally extending ribs having flanges
at their opposite ends which move radially inwardly as the bore is
constricted.
The flanges are arranged radially of the annulus and the sides of
adjacent flanges are spaced apart so that they may move inwardly as
the annulus is constricted. The radially innermost ends of the
flanges are disposed substantially adjacent the bore of the annulus
in the unconstricted position of the annulus, so that as the
annulus is constricted, these ends will move into the bore of the
preventer housing. Thus, even though the bore of the annulus moves
inwardly beyond the inner ends of the flanges, the latter overhang
a sufficient portion of the annulus to prevent its being blown out
by well pressure.
Obviously, however, as the packer is used to close off on itself,
or even on small objects in the bore of the preventer housing, a
greater amount of overhang may be required. With the preventer
shown in the aforementioned patent, this could be accomplished only
by reducing the diameter of the housing bore or by extending the
inner ends of the flanges into the housing bore, which would reduce
the effective or useful diameter therethrough when the packer is
unconstricted. The operating conditions for which the preventer is
designed do not normally permit this.
Also, since there are spaces between the sides of the flanges, the
portions of the annulus beneath these spaces must be recessed.
Otherwise, the annulus would be extruded into the spaces and
thereby either cause the extruded rubber to be pinched off or
prevent full and uniform inward movement of the inserts.
An object of this invention is to provide an annular preventer and
a packer therefor in which the overhang is increased without a
reduction in the effective housing bore in the unconstricted
position of the packer.
Another object is to provide an annular blowout preventer and a
packer therefor in which the effective radial extent of each of the
flanges or other platelike insert parts at opposite ends of the
packer increases as the annulus is constricted.
A further object is to provide such a preventer in which the ends
of the annulus are confined against extrusion between such parts
and in which the inserts as a whole are caused to move in unison
upon constriction of the annulus.
These and other objects are accomplished, in accordance with the
illustrated embodiment of the present invention, by an annular
blowout preventer in which the plates of a substantially circular
series of rigid plates on at least one end of the packer annulus
have their radially innermost ends substantially adjacent the bore
of the annulus and are skewed with respect to such bore when the
annulus is unconstricted. As a result, the plates swing into more
radial positions, as the annulus is constricted, to increase their
effective radial extents. Thus, the plates are caused to overhang
the annulus to a greater extent than heretofore possible with
annular preventers having conventional packers with radially
disposed insert flanges of the type above described.
More particularly, the sides of the plates are wedge-shaped in plan
and adjacent one another to confine the annulus against extrusion
between them and to cause them to move in unison as the annulus is
constricted. In the illustrated embodiment of the invention, the
plates are arranged at both ends of the annulus so that the packer
may be arranged in the preventer housing with either end up.
Preferably, ribs extend through the annulus in circularly
spaced-apart relation, and each is connected to a plate at each end
which overhangs the rib to form a flange. This controls to some
extent the flow of the resilient annulus material and minimizes the
tendency for the overhanging ends of the plates to bend under
pressure.
In the drawings, wherein like reference characters are used to
designate like parts;
FIG. 1 is a perspective view of an annular blowout preventer
constructed in accordance with the present invention, as seen from
the top and side thereof, and with a portion removed to show a pipe
within the bore of the packer in its unconstricted position;
FIG. 2 is a vertical sectional view through the blowout preventer
of FIG. 1, as seen along broken line 2-2 of FIG. 1;
FIG. 2A is a partial top plan view of the packer of the preventer
of FIGS. 1 and 2, as seen along line 2A-2A of FIG. 2, with the
packer in its unconstricted position and showing in broken lines
the ribs of its rigid inserts;
FIG. 3 is a vertical sectional view through a portion of the
packer, upon an enlarged scale and as seen along broken line 3-3 of
FIG. 2A;
FIG. 4 is a cross-sectional view, on an enlarged scale and as seen
along broken line 4-4 of FIG. 2, of a connection between adjacent
packer constricting parts which synchronizes their radial
movement;
FIG. 5 is a partial vertical sectional view of the preventer,
similar to FIG. 2, but showing the packer upon constriction
inwardly to seal about the pipe in the bore of the housing;
FIG. 5A is a top plan view of the packer, as seen along line 5A-5A
of FIG. 5 and similar to FIG. 2A, but with the packer in the
constricted position of FIG. 5;
FIG. 6 is another partial sectional view similar to FIG. 5, but
showing the packer in a further constricted position to close an
open hole in the bore of the preventer housing;
FIG. 6A is a top plan view of the packer, as seen along line 6A-6A
of FIG. 6, but with the packer in the constricted position of FIG.
6;
FIG. 7 is a perspective view of a rigid insert; and
FIG. 8 is a horizontal sectional view of the insert, as seen along
broken line 8-8 of FIG. 7.
With reference now to the details of the above described drawings,
the preventer, which is designated in its entirety by reference
character 20, includes a housing 21 which is annular in shape and
has a cylindrical bore 22 extending axially through it. Threaded
holes 23 and ring grooves 24 are provided at both ends of the
housing for coaxial connection and sealing to other wellhead
members (not shown).
With the preventer 20 thus connected as a part of the wellhead, a
drill pipe P forming part of the drill string may extend through
its bore 22 and into the well bore. Alternatively, a Kelly or other
out-of-round member may extend through the bore 22 of the blowout
preventer. Still further, the bore may be empty so as to form an
"open hole" therethrough. As known in this art, there may be
occasion for the preventer to be used in sealing about the member
in the hole, such as the pipe P or the Kelly, so as to close off
the annular space between such member and the bore 22, or
alternatively to seal off with itself so as to close an open
hole.
Housing 21 is made up of a body 25 which is generally L-shaped in
vertical, half cross section to provide an upwardly opening shelf
about its interior, and a cap 26 disposable over the upper end of
the body 25 to form an annular recess 27 about bore 22. Cap 26 has
a bore 22a therethrough which forms a continuation of a bore 22b
through the lower end of body 25, the two bores thus forming the
bore 22 through the housing. Body 25 includes a bridging ring 40
(to be described below), and cap 26 and the top surface of the ring
form the upper and lower ends 27a, and 27b, respectively, of the
recess. The outer wall of recess 27 is concentric with bore 22 of
the housing, and the ends 27a, and 27b of the recess are
perpendicular to its axis.
Cap 26 is secured to the upper end of the body 25 by a series of
cap screws 28 extending through holes in the cap for connection
with threaded holes 29 in the body 25. Threaded holes 30 in cap 26
may receive eyes for lifting it into and out of place. An O-ring 31
about a reduced lower end portion of the cap seals with respect to
an inner annular wall 32 of the body 25 above the recess 27.
A packer 33 is disposed within the recess 27 of the preventer
housing 21 for movement between an unconstricted position in which
its bore 35 is substantially axially aligned with the housing bore
22, as best shown in FIGS. 1 and 2, and a constricted position in
which its bore 35 is moved radially inwardly into the housing bore
for sealing about the pipe P, as best shown in FIG. 5, or for
sealing upon itself when the bore is empty, as best shown in FIG.
6. As will be described in detail below, the packer is so moved by
means of constricting parts including laterally extending segments
36 disposed about the outer side of the packer within recess 27 and
adapted to be moved radially inwardly and outwardly by means of the
hydraulically operated pistons.
Packer 33 is cylindrical in shape, with its outer side and bore 35
concentric, and its ends 37 and 38 perpendicular to the axis of the
bore 35. It fits closely within the upper and lower ends 27a and
27b of the recess and, as best shown in FIG. 2, when the packer is
unconstricted, segments 36 are disposed with their inner arcuate
faces adjacent its outer side and their outer arcuate faces
adjacent the outer side of the recess 27. Bore 22b of the housing
is connected to the radially outer portion of the recess 27 behind
the outer side of the packer by a series of slots 39 formed in a
bridging ring 40 to permit well pressure to act over the outer side
of the packer.
The constricting segments 36 are circumferentially spaced to permit
them to move radially inwardly to constrict the packer. As will be
apparent from FIG. 4, they are caused to move in unison by means of
pins 60 connecting the opposite ends of adjacent segments. Thus,
one end of each pin is threadedly received in a socket 61 in one
segment, while its other end is slidably received in a socket 62 in
an adjacent segment. Each segment is so moved by means of a piston
63 having a seal ring 69 slidable within a cylinder 64 extending
inwardly from the outer side of body 25 of housing 21. Each piston
is connnected to a segment 36 by a rod 66 having a stud 65
threadedly connected between a socket on the innner end of the rod
and a central hole in the segment. Each rod 66 extends through a
seal such as an O-ring 67 carried within an opening 68 through the
housing 25 between the recess 27 and a cylinder 64.
Upon removal of the cap 26 from the body 25 of the housing, the
packer 33 may be lifted from or lowered into the recess 27. With
the packer removed from the recess, access may be had to the
segments 36 for replacing or repairing them. Thus, the threaded
connection of each stud 65 to the piston rod enables the rod to be
disconnected from the stud, so that the segment may be withdrawn
and removed from its operating position within the recess 27.
The outer ends of cylinders 64 are closed by means of a ring 70
which surrounds body 25 and is seated on a shoulder 71. This ring
is normally prevented from moving upwardly by a pin 70a removably
connected to cap 26. However, when the pin is removed, the ring may
be lifted from and lowered into position for closing the cylinders
64. When lifted, the ring 70 permits access to any one or all of
the pistons 63 for replacing or repairing them. Due to the threaded
connection of the piston rod 66 to the stud 65, the piston may be
rotated so as to release it from the stud 65 and permit it to be
withdrawn from its cylinder 64.
Seal rings 72 and 73 about body 25 above and below cylinders 64
seal with respect to ring 70 to form an annular space about pistons
63 into which pressure fluid may be introduced through a conduit 74
connecting with a passageway 75 leading thereto. This pressure
fluid urges the pistons inwardly and thus the packer to a
constricted position.
Alternatively, pressure fluid may be introduced into cylinders 64
on the inner side of pistons 63 to urge them outwardly and permit
the packer to expand. This fluid is introduced through a conduit
75a, connecting with an annular passageway 76 which is formed from
the lower side of the body 25 and then covered by a ring 77 welded
to the body. Individual passageways 78 then connect passageway 76
with the inner end of each cylinder 64.
Packer 33 includes a massive annulus 34 of rubberlike material
having its bore 35 formed therethrough and a circular series of
rigid inserts 41 which extend through the annulus from one end to
the other. Each such insert is bonded to the annulus and includes a
rib 42 having a flange 43 at each end which overhangs the rib on
all sides, as best shown in FIGS. 7 and 8. The ribs are disposed
generally midway between the bore 35 and the outer side of the
annulus, while the flanges are disposed with their radially
innermost ends 43a, flush with the bore when the annulus is
unconstricted.
The radially outermost ends 43b, of the flanges 43 are disposed
inwardly of the outer side of the annulus to leave an annular
portion at each end of the annulus surrounding the flanges. As best
shown in FIG. 3, each annular portion protrudes at 44 beyond the
adjacent end surface of the flange 43 for engaging the opposite end
surface of recess 27. Inward movement of the segments 36 constricts
the packer, urging the top protuberance upwardly against the upper
end of the recess to supplement the action of well pressure on the
lower end of the packer.
Although the protruding surfaces on the lower end of the annulus
may also form a seal against the lower end 27b, of the recess, the
lower portion 22b, of the bore is nevertheless connected through
slots 39 to the recess behind the annulus. Thus, well pressure will
still have access to the recess 27 behind the outer wall of the
annulus. Since the protruding surface on the upper end of the
annulus seals with respect to the upper end 27a, of the recess, the
differential between this well pressure and atmospheric pressure in
the upper portion 22a of the bore is effective over a substantial
portion of the height of the packer to supplement the force of the
actuators of the segments 36 in maintaining the annulus in its
constricted position.
Inasmuch as the packer is symmetrical end-for-end, it may be
disposed in the recess 27 of the housing with either end up. Thus,
if an upper protruding surface is damaged, the packer may be
inverted to dispose the effective lip at its upper end.
As the packer is constricted, the rigid inserts 41 are also caused
to move inwardly, although to a lesser extent than the annulus
itself. That is, as will be appreciated from a comparison of FIGS.
1 and 2 with FIGS. 5 and 6, upon constriction of the packer, the
vertically midportion of its bore 35 will move radially inwardly
past the innermost ends 43a, of the flanges 43 of the inserts. As
the rigid inserts move inwardly, these innermost ends move into the
bore 22 of the housing to overhang a portion of the annulus which
has moved into the bore 22, thereby reducing the likelihood of
extrusion of the annulus past the flanges.
As shown in FIG. 2A, when the packer is unconstricted, the flanges
43 are skewed with respect to the bore of the packer. Thus, the
axis of each flange--i.e., a plane bisecting the flange from end to
end--extends at an acute angle with respect to a radius of the
packer which passes through the centroid of the flange. Since
constriction of the annulus causes its inner portions to move
radially inwardly at a greater rate than the outer portions
thereof, and the rigid inserts 41 are bonded to the annulus, the
flanges will swing to a more radial orientation with respect to the
packer bore. Thus, as can be seen from the drawings, the flanges
swing from the skewed positions of FIG. 2A, when the packer is
unconstricted, to a more radial position when the packer is
constricted to seal about a pipe, as shown in FIG. 5A, and to a
still more radial position when the packer is constricted to seal
upon itself, as shown in FIG. 6A.
Thus, the effective radial extent of each flange--i.e., the radial
distance between the radially innermost and outermost ends 43a and
43b thereof--increases during constriction of the packer. This is
in contrast to the behavior of initially radially disposed flanges,
as in the packers of the above mentioned patent, which have the
same effective radial extent at all degrees of constriction of the
packer. As a result, the rigid inserts of the packer of the present
invention occupy less initial space for a given amount of
subsequent overhang.
As in the packer of the previously mentioned patent, the rubber
forming the annulus is free to flow between the circularly
spaced-apart ribs 42 as the packer is constricted. However, as
distinguished from the prior packer, the sides of the flanges 43 of
adjacent inserts 41 engage one another in both the unconstricted
and constricted positions of the annulus. Thus, as previously
described, the rubber at opposite ends of the annulus is confined
against extrusion between the flanges. Also no one flange at an end
of the annulus is free to move relatively to the remainder, so that
in fact all the flanges and thus the inserts move in unison.
The opposite sides of the rib 42 of each insert are parallel to one
another and also arranged with the vertical plane bisecting each
rib disposed at an acute angle to the radius of the annulus passing
through the centroid of the rib. More particularly, the opposite
sides of rib 42 are disposed approximately within planes of least
strain of the rubber of the annulus during movement of the annulus
from unconstricted to constricted positions, so as to reduce the
likelihood of breaking the bond between the ribs and the annulus,
with consequent reduction of its effective life.
These planes of least strain may extend at acute angles on either
side of the radius. However, in the case of the inserts 4, which
swing as a whole toward more radial positions during constriction
of the annulus, it is preferred that the sides of the rib be so
disposed as to also be swung to more radial positions as the
annulus is constricted. In this way, the ribs do not detract from
the tendency of the inserts 41 to twist as a whole toward their
more radial positions.
From the foregoing it will be seen that this invention is one well
adapted to attain all of the ends and objects hereinabove set
forth, together with other advantages which are obvious and which
are inherent to the apparatus.
It will be understood that certain features and subcombinations are
of utility and may be employed with reference to other features and
subcombinations. This is contemplated by and is within the scope of
the claims.
As many possible embodiments may be made of the invention without
departing from the scope thereof, it is to be understood that all
matter herein set forth or shown in the accompanying drawings is to
be interpreted as illustrative and not in a limiting sense.
* * * * *