Note: Descriptions are shown in the official language in which they were submitted.
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SE~EAR RAM APPARATUS
~Lk~round of the Invention
1. Field of the Invention
The present invention generally relates to shear ram apparatus for use in blowoutpreventers used for sealing off oil and gas wells during emergency situations in order to
5 contain dangerous blowouts. More specifically, the present invention is directed to shear ram
apparatus for severing and sealing about a variety of borehole retrievables, more particularly,
flexible lines, and most particularly, multi-strand cable and the like which is often not
severed by conventional shear ram apparatus.
2. DescriQn~of the Background
Several different general types of blowout preventers are known in the art. One of
these is the ram type blowout preventer which typically includes a housing having a
throughway for the drill pipe. First and second ram assemblies are mounted in the housing
on opposite sides of the throughway. These assemblies are reciprocated laterally inwardly
and outwardly, i.e., toward and away from each other. These assemblies are moved
1~ inwardly to close the blowout preventer when it becomes necessary to seal off the well.
Ram type blowout preventers are fur~her subdivided into various types. One type is
commonly referred to as the pipe ram. In this type of apparatus, the ~n assemblies, when
moved laterally inwardly to the closed position, simply seal about the outer diarneter of the
drill pipe, thereby sealing off the annulus between the drill pipe and the walls of the well
bore. Exemplary prior pipe rarn assemblies are disclosed in U.S. Patent No. 3,434,7 9.
A second ram type blowout preventer is commonly referred to as a shear ra n. In this type,
the ram assemblies, when reciprocated inwardly, actual sever the drill pipe and subsequently
seal against each other in such a way that both the drill pipe itseIf and the surrounding
annulus are sealed off in the sense that the closed shear ram prevents communication *om
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the space below to the space above the blowout preventer. Exemplary shear ram assembh~s
are disclosed in U.S. Patents Nos. 3,736,982, 4,0819027 and 4,540,0a,6, the disclosures and
drawings of which are incorporated herein by reference. Both pipe rarns and shear rams are
typically included in a complete blowout prev~nter staclc.
S The shear rarn apparatus disclosed in the above patents ~Yere intended to sever and
seal about conventional drill pipe. Rigid, conventional drill pipe is readily severed by the
lateral movement of the blade and anvil of the opposed ram assemblies. However,
conventional shear ram assemblies have been less successfully used to sever and seal about
more flexible lines. In fact, conventional shear ram assemblies have been particularly
ineffective in severing and sealing about multi-strand cable which tends to separate and
spread out across the blade-anvil interface rather than being neatly severed. Once separated
and spread out, multi-strand cable tends to fold over, causing relative longitudinal movement
of the opposed blade and anvil. This movement causes the blade and anvil to ride over each
other on the spread out cable resulting in failure to cleanly and completely sever and seal the
multi-strand cable. For this reason, the dessribed, conventional shear ram apparatus is
inappropriate for use with many borehole retrievables, particularly flexible lines such as coil
tubing, slicldines, w~relines and cables, most particularly with multi-strand cables.
Accordingly, there has been a long felt but unfulfilled need in the oil and gas industry for
improved shear rarn apparatus capable of cleanly severing and sealing about flexible lines
and, particularly, multi-strand cable.
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Summary of he nvention
The present invention is directed to shear rarn apparatus for severing and sealing
about borehole retrievables, particularly about flexible lines, and most particularly about
multi-strand cable. The present invention provides an improved shear rarn apparatus
5 including means for preventing relative longitudinal movement of the blade member and anvil
carried on opposable rarn assemblies when those assembles are moved laterally inwardly to
their shearing or closed position. Shear ram apparatus in aceord with the present invention
offers the significant advantage of being able to shear a vaIiety of flexible lines, most
particularly multi-strand cable, which could not be cleanly sheared and sealed by
10 conventional shear ram apparatus.
Shear ram apparatus in accord with the present invention ineludes a housing body
having a throughway for receipt of the borehole retrievable, particularly a flexible line, and
most particularly a multi-strand cable. The apparatus further includes opposed first and
second ram assemblies mounted in the housing on opposite sides of the throughway for
1~ reciprocation laterally inwardly and outwardly. I Connected to the first and second ram
assemblies, respectively, are first and seeond drive means for e~fecting the desired
reciprocation. The shear ram apparatus fi~rther includes a blade member carried on the
late~ally inward side of the first ram assembly and an anvil formation on the laterally inward
side of the second rarn assembly and positioned for cooperation with the blade member to
20 apply a shearing force to the multi-st~and cable or other borehole retrievable when the ram
assemblies are moved laterally inwardly. Also included are first and second seal means
carried, respectively, in the first and second ram assemblies for sealing the throughway
ag~inst longitudirlal flow when the ram assemblies have been reciprocated inwardly to their
shearing and sealing position. Finally, the shear ram apparatus of the present invention
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includes means for preventing relative longitudinal rnovernent of the blade member and anvil
when the ram assemblies ~Lre moved laterally inwardly. The preferred means compnses a
plurality of keys projecting laterally inwardly from the inward side of one of the ram
assemblies for cooperation with guide means on the inward side of the other ram assembly.
5 In a preferred embodiment the key and guide means are disposed tc the side ~f the blade
member and the anvil and engage before the blade mernber contacts the anvil as the opposed
first and second ram assemblies are moved laterally inward to shear and seal.
The opposable shear ram assemblies and the shear ram apparatus of the present
invention provide an improved apparatus for severing and sealing about flexible lines and
10 particularly about multi-strand cables. By preventing relative longitudinal movement, i.e.,
longitudinal separation, of the blade member and anvil during the lateral movernent of the
closing operation, the impr~ved shear ram apparatus of the present invention prevents flexible
lines, and particularly multi-strand cable, from guiding and longitudinally separating the
blade member and anvil which would prevent clean shearing and sealing by the shear ram
15 apparatus. This improved feature solves the long felt but unfulfilled need in the oil and gas
industry for a rugged? shear ram device capable of severing all borehole retnevables, f~m
ngid drill pipe to highly flexible lines, including multi-strand cables. These and other
meritorious features and advantages of the present invention will be more fully appreciated
from the following de~ailed description and claims.
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Brief Descnption of the Drawin~~
Other features and intended advantages of the present invention will be more readily
apparent by the references to the following detailed description in connection with the
accompanying drawings, wherein:
Fig. 1 is a cross-sectional illustration of a prior art shear ram blowout preventer
apparatus illustrating separation of the blade and ~mvil by a multi-strand cable and the
resulting failure to sever and seal;
Fig. 2 is a top plan illustration of the prior art shear ram blowout preventer apparatus
of Fig. 1 illustrating in cross-section the separated and unsevered multi-strand cable;
Fig. 3 is a cross-sectional illustration through a shear ram blowout preventer apparatus
in accord with the present invention with the ram assemblies in the open position;
Fig. 4 is a top plan illustration viewed from the line 4-4 of Fig. 3 of t`he shear ram
bl~wout preventer apparatus in accord with the present invention illustrating the ram
assemblies in the open position;
Fig. 5 is a cross-sectional illustrahon of the shear ram blowout preventer apparatus
of the present invention illustrating the ram assemblies in the closed, sealing position with
the key and guide means engaged to prevent relative longitudinal movement of the blade and
anvil;
Fig. 6 is a f~ont elevational view of the laterally inward side of ~he ISrst ram assembly
along the line ~6 of Fig. 3 illustrating a blade and guide means in accord with the present
i~vention; and
Fig. 7 is a front elevational view of the laterally inward side of the second ram
assembly ~hrough the line 7-7 of Fig. 5 and including the blade and guide means of the first
~am assembly in cross-section engaged with the keys of the second ram assembly in accord
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with the present invention.
While the invention will be described in connection with the presently preferred
embodiment, it will be understood that it is not intended to limit ~he invention to this
embodiment. On the contrary, it is intended to cover all alternatives, modifications and
5 equivalents as may be included in the spirit of the invention as defined in the appended
claims.
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De_i~ed Description of the Pre erred Emb~iiment
The present invention provides shear ~rn apparatus for use in blowout preventers for
severing and sealing about a borehole retrievable: and, particularly, a llexible line.
Exemplary of a rigid borehole retrievable is a string of drill pipe or a sinker bar. E~xemplary
S of flexible borehole retrievables are coil tubing, slicklines, wirelines and multi-strand cables.
The shear ram apparatus of the present invention is particularly useful in severing and sealing
about flexible borehole retrievables and, particularly, rmulti-strand cable. Conventional shear
ram apparatus is characterized by a blade member and an anvil formation carried on the
laterally inward side of opposed first and second rarn assemblies. In conventional shear rarn
10 apparatus the blade member and anvil formation are moved laterally inwardly to sever and
seal. However, the blade and anvil may be guided into longitudinal movement and
separation by multi-strand cable and other flexible lines, thus preventing the apparatus from
cleanly severing and sealing such flexible lines.
Figs. 1 and 2 illustrate prior art shear ram blowout preventer apparatus. These
lS figures illustrate the undesirable longitudinal separation of the blade member and the anvil
fonnation when the rarn assemblies have been moved laterally inwardly in an unsuccessfill
at~empt to sever and seal about a multi-s~and cable. The shear ram apparatus of the present
invention is distinguishable over such con~entional apparatus in that the opposable first and
second ram assemblies include means for preventing relative longih~dinal movement and
20 undesirable sepa~ation of the blade member and anvil formati~n when the ram assemblies are
moved laterally inwardly.
Referring to Figs. 1 and 2, there is shown a ram-type blowout preventer, more
specifically, a shear ram app~ ratus ~mprising a housing 100. Housing 100 defines a central
~ughway 11~, disposed generally vertically in use, for receipt of a borehole re~ievable,
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typically a string of drill pipe or other flexible line, e.g., coil tubing, slickline, wireline or
multi-strand cable 114. As used herein, terrns such as "longitudinally" and "laterally" should
be construed with reference to the centerline of throughway 112 unless otherwise indicated.
For convenience, it is noted that the centerline of throughway 112 is generally coincident
S with that of the drill pipe or cable 114 in use. Also, for convenience, terms such as
"vertically" and "horizontally" will be used with reference to the positions normally assumed
by various parts of the apparatus in use, and should not be construed in a limiting sense.
Housing 100 defines a pair sf chambers 116 and 118 on laterally opposite sides of and
communicating with throughway 112. Chambers 116 and 118 are substantially identical and
lû house, respectively, first and second ram assemblies.
The first ram assembly, housed in chamber 116, comprises lower ram block 120
having laterally inward side 146. The laterally inward side 146 of rarn block 120 is inset and
charnfered at 146a. Ram block 120 includes cavity 122 having reduced diameter mouth 124
opening laterally ou~wardly. Cavity 122 receives flange member 126 conn~cted by reduced
diarneter neck 128 to piston rod 130. Neck 128 extends through mou~ 124 of cavity 122
with piston rod 130 being located outwardly thereof. Because of the reduced diameters of
mouth 124 and neck 128, flange 126 and piston rod 130 form opposed shoulders abutting
laterally outward por~ion 125 of ram block 120. In a manner well h~own in the art, piston
rod 130 iS CoMeCted to a piston housed in a cylinder integral with housing 10. Thus, piston
rod 130 serves as a drive member whereby first ram block 120 may be reciprocated laterally
inwardly and outwardly.
Ram block 120 carriles in an undercut formation 136 on its late~lly inward side 146
an L-shaped shear blade 132. Shear blade 132 is cha~acterized by projecung cutting portion
134 and is held within undercut formation 136 by hofizontally disposed bolts (not shown).
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Ram block 120 includes an arcuate groove 142 on its upper surface, a transverse
groove 144 along undercut formation 136 and vertical grooves (not shown) extending
upwardly from the ends of transverse groove 144 to the ends of arcuate groove 142 for
receiving a seal. The first ram assembly further comprises a first seal, conveniently in the
S forrn illustrated in Fig. 9 of U.S. Patent No. 4,54û,046, previously incorporated herein by
reference. Ihis seal is a monolithic elastomeric body comprising an arcuate seal portion 138
connected at its inward ends by vertical seal portions (not shown) to laterally inward,
transverse seal portion 140.
The second ram assembly which is housed in chamber 11 8 comprises upper ram bloclc
150. The main drive means tpiston rod 130') and its manner of connection to ram block 150
at its laterally outward por~on 155 are substantially identical to those for ram blcck 120.
Therefore, these parts will not be described in detail, but have merely been given like
re~erence numerals plus the symbol ~n (prime).
Upper ram block 150 is characteri~ed further by laterally inner side 148, inset and
chamfered 148a and including cutting anvil forrnation 152 on its lower surface. Behind anvil
formation 152, ram block 150 has been undercut to ~orm re~ss 154. Ram block 150 further
includes along its upper surface an arcuate groove 156 connected at its inward ends by
vertical grooves (not shown~ to the ends of the laterally inward portion of recess 154. The
groove system thus formed is configured to receiYe a second monolithic elastomeric seal
body sirnilar ~o that previously described and to that illustra~ed in Fig. 10 of U.S. Patent No.
4,540,046. T~is second seal includes arcuate portion 158 connected at the inward ends
the~eof by ~ tical portions (no~ shown) to the ends of transverso seal portion 160. Rigid
5Upp~t baI 162 bolted within recess 154 maintains~he seal in place.
Figs. 1 and 2 illustrate the longitudinal movement and separation of blade member
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132 and anvil ~orrnation 152 in a conventional shear ram assembly caused by separation of
a multi-strand cable 114 into its individual s~rands 114a. Shear ram blowout preventer
apparatus in a~cord with the present invention overcomes this problem so that flexible lines,
including multi-strand cables, are easily and cleanly severed ancl sealed.
Shear ram blowout preventer apparatus in accord with the present invention is
illustrated in Figs. 3-7. Figs. 3 and 4 illustrate that sh ar ra n apparatus ln the open position.
Fig. S illustrates that apparatus in the closed position. Figs. 6 and 7 illustrate in cross-
section the interlocking keys and slots which prevent relative longitudinal movement of the
blade member an~ anvil formation in accord with the present invention.
Housing 10 defines a central throughway 12, disposed generally vertically in use, for
receipt of a borehole retrieYable, preferably a multi-strand cable ~not illustrated). Housing
10 further de~mes a pair of charnbers 16 and 18 on laterally opposite sides of and
communicating with throughway 12. Chambers 16 and 18 are substantially identical and
housel respectively, first and second ram assemblies.
The first ram assembly, housed in chamber 16, compnses ram block 20 having
laterally outward portion 22 for connec~on to the drive means and laterally inward portion
24 for carrying the shear blade 40. Lower sam block 20 includes cavity 26 having reduced
diameter mouths 28 opening laterally outwardly. Cavity 26 receives flange members 30
connected by reduced diameter necks 32 to a piston rod 34. Necks 32 extend through
mouths 28 of cavity 26 with piston rod 34 being located outwardly thereof. Because of the
reduced ~iameters of mouths 28 and neeks 32, flange members 30 and piston rod 34 ~orm
opposed shoulders abutting laterally outward por~on 22 of ~am block 20. In a manner well
known in the art, piston r~i 34 is connected to a piston housed in a cylinder integral with
housing lO. Thus, piston rod 34 serves as a drive memb~r whereby first ram block 20 may
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be reciprocated laterally inwardly and outwafdly.
On the laterally inward surface of portion 24 of rarn block 20 is inset 36 for receiving
the borehole retrievable, e.g., pipe, cable or the liket to be sheared. Mounted on the lower
portion of the laterally inward surface of ram block 20 is shear blade 40. Blade member 40
S is generally L-shaped in cross-section, having a laterally inwardly extending cutting portion
42 and a mounting shan~ 43 extending downwardly from the laterally oultçr extremity of the
cutting portion 42. As shown in Fig. 4, cutting portion 42, as viewed in plan, has a shallow
notch 46 formed by oppositely inclined edges 44 to increase its contact area with the
retrievable to be cut. Mounting shank 43 of blade member 40 includes a plurality of counter-
10 sunk bores 56 for cooperation with a plurality of bores 58 in ~he lateIally inward surface ofram block 20 for mounting of blade member 40 thereon with a plurality of mounting bolts
or screws 38. As is evident from Figs. 3, 4 and 6, the most outwardly portions 96 of
mounting shank 43 extend across the depth of cuttin portion 42 of blade member 40 while
the central portion is inset at 45. Accordingly, outer bores 56a for screws 38a are longer
15 than cen~l bores 56.
Ram blocX 20 includes a seal means carried in an appropriate groove system. The
disposition of the various parts of the groove system and the seal means relative to the
remainder of the first ram assembly is readily understood with reference to Figs. 3, 4 and
6. Ram block 20 includes arcu2te groove 48 on its upper surface, transverse groove 50
20 along its laterally inward surface and vertical ~rooves 49 extending upwardly f~om the ends
of transverse groove 50 to the ends of arcuate groove 48 for receiving a first seal means.
The first ram assembly funher comprises a first seal, preferably in the form illushated in
Fig~ 9 of U.S. Patent No. 4,540,W6. The seal is a monolithic elastomenc body comprising
an arcua~e seal portion 52 connected at its inward ends by vertical seal portions 53 to
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laterally inward, transverse seal portion 54.
The second ram assembly which is housed in chamber 10 comprises upper ram block
70. The main drive means (piston rod 34 ) and its manner of connection to ram block 70
at its laterally outward portion 72 are substantially identical to those for ram block 20.
5 Therefore, these parts and their cooperation will not be described in detail, but have merely
been given like reference numerals plus the symbol " "' (prime).
Upper ram block 70 is characterized by laterally outward portion 72 and laterally
inward portion 74 terminating in laterally inward surface 76. Inward surface 76is inset at
78 to aid in positioning a borehole retrievable, e.g., a multi-strand cable, for cutting relative
to notch 46 of blade member 40. Inward surface 76is inset and cha nfered 82 along its top
side and provides anvil fonnation 80 along its lower leading edge for cooperation with
cutting portion 42 of blade member 40. Ram block 70is undercut 94 for receiving blade
member 42 and the severed cable or other borehole retrievable in the closed position.
Ram block 70 includes arc~te groove 84 on its upper sufface, transverse groove 86
I5 along undercut for nation 94 and vertical grooves 85 extending upwardly from the ends of
transverse groove 86 to the ends of arcuate groove 84 for receiving a second seal means.
The s~cond ~arn assembly further comprises a second seal, preferably similar to that
p~vionsly described above and illustrated in Fig. 10 of U.S. Patent No. 4,~40,046. This
seal is a monolithic elastomeric body comprising ~ arcuate seal portion 88 connected at its
20 inward ends by vertical seal portions 89 to laterally inward, transverse seal portion 90. Rigid
s~pport bar 92 is disposed within recess 86 behind transverse seal portion 90 eo maintain the
seal in pLace.
Longitudinal or vertieal, as typically disposed, relative movement of blade 40 on first
am block 20 with respect to anvil formation 80 on second Mm block 70 is prevented by
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cooperating keys 64 extending inwardly from the inward surface of ram block 70 for
cooperation with retaining means or slots 60 along the outer edges of extended outer portions
96 of mounting shank 43 of blade rnember 40. Cc~,peration of keys 64 with SIOtS 60 is
shown in Fig. 7 where keys 64 extend inwardly below upper retaining surfaces 62 toward
S vertical surfaces 63 of retaining slots 60 to prevent keys 64 and anvil formation 80 from
relative upward or longitudinal movement with respect to and away ~rom blade member 40.
In Figs. 3 and 4 it is seen that leading edges 66 of keys S4 preferably extend beyond the
laterally inward surface 76 and anvil formation 80 of ram assembly 70. Accordingly, leading
edges 66 of keys 64 engage retaining slots 60 be~ore anvil fiormation 80 contacts cutting
portion 42 of blade member 40. Thus, keys 64 are engaged with retaining slots 60 to
prevent relative longitudinal movement of anvil formation 80 relative to blade member 40
before cGntact with multi-strand cables and other small retrievables could produce unwanted
relative vertical or longitudinal movement. The inwardly inclined surfaces 44 toward notch
46 of blade member 40 further enhance this last feature.
The ~oregoing description of the invention has been directed in primary part to a
particular embo~iment in accordance with tne requirements of the patent stah~tes and for
purposes of explanation and illustration. It will be apparent, however, to those sl~lled in the
art that many modifications and changes in the specifically described shear ram apparatus
may be made without depar~ng from the scope and spirit of the invention. For example,
~0 while the illus~ated embodiment includes a pair of keys 64 disposed on one rarn assembly
f~r cooperation with a pair of retaining slots 60 on the other assembly, other configurations
are readily apparent. For example, each assembly m~ght include a key and retaining slot for
cooperation with, respective;ly, a retaining slot and key on the other assembly. Fu~her, keys
64 might extend inwardly further than those illustrated to engage deeper retaining slots 60
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in both the open and closed positions of the ram assemblies ensuring no possible relative
longitudinal movement of the blade member and anvil fiormation. Therefore, the inven~ion
is not restricted to the preferred embodiment illustrated but covers all modifications which
may fall within the soope of the following claims.
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