Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: Oil Well Blow-Out Preventer And Sealing Device
5 FIELD OF THE INVENTION
This invention relates to an appa~lus for preventing blow-outs in an oil well and for
the sealing of an oil well in the case of breakage or removal of a pump rod, thereby
preventing the spillage of oil or fluids from the well.
BACKGROUND OF THE INVENTION
Most production oil wells contain a well casing within which a production tubing
string is positioned. The production tubing string serves as both a means to easily
insert and remove a pump rod and also provides a conduit for the extraction of oil
15 and fluids from the well. Typically production tubing strings are held within the well
casing through the use of a variety of flanges, hangers and other types of devices that
tightly seal the well casing allowing fluids to escape or be removed by way of the
production tubing string only.
20 In many cases an oil reserve or pocket is under considerable underground ples~ule.
Once a well has been drilled, the static pressure to which underground oil is subjected
often forces oil upwardly through the well. It is therefore important for
conservation, safety and environmental reasons to ensure that there are safe and
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reliable methods of closing off both the well casing and the production tubing string
to prevent the unwanted or accidental spillage of oil or other fluids from the well.
In the case of the production tubing string, manually actuated valves or similar
structures, often referred to as blow-out preventers, have been developed specifically
5 for this purpose. Typically such devices provide a sealing mechanism that
encompasses the pump rod in the production tubing string in order to effectively cap-
off the well. However, such devices offer little ~si~t~nce in instances where a pump
rod breaks near its top, or where the rod has been removed from the production
tubing string. In cases of pump rod removal or failure, others have proposed a
10 variety of different methods and devices to seal off the well. These include bolting
a flange over the top of the production tubing string and the use of large gate valves
mounted in the production tubing string. The inherent short comings with these prior
art devices include their inability to operate automatically in the event that a pump
rod breaks when a technician is not readily available to shut down the well.
Furthermore, devices that have been proposed and used by others have tended to be
large and cumbersome and must be bolted or screwed to the production tubing string.
The connection of such devices to the production tubing string results in a wellhead
of considerable height and weight. Traditionally such wellheads have been referred
20 to as "Christmas trees" due to their size and the fact that there are usually a large
number of elements pointing outwardly from various parts of the tubing string and
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the components mounted thereon. The servicing of oil wells having such "Christmas
trees" attached to their production strings tends to be both complex and time
consuming. In addition, v~ith the bolting or screwing together of a large number of
component parts, leaking at each junction is often a problem. Where a well casing
S is inclined or slanted, the considerable weight of these additional devices can place
a significant degree of torque upon the various connections, sometimes resulting in
failures or stress fracturing.
SUMMARY OF THE INVENTION
10 The invention therefore provides an oil well blow-out preventer and sealing means
which overcomes the shortcomings of these prior art devices through the
incorporation of a structure providing a unitary body that includes both a blow-out
prevention means and a sealing means to automatically prevent the flow and spillage
of fluids from the oil well should the pump rod break or be removed. The blow-out
15 preventer and sealing device of the present invention also provides an internal and
integrated flow tee in con~llu,lication with the production tubing string to provide a
means to transport fluid from the well.
Accordingly, in one of its aspects the invention provides an oil well blow-out
20 preventer and sealing device for use on an oil well having a well casing, a wellhead,
a production tubing string, and a pump rod receivable within the production tubing
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string, the device comprising: a central housing member for mounting on the
wellhead, said central housing member including a flow passageway and a pump rod
passageway, said flow passageway being in communication with the production
tubing string and providing a means for fluid to be removed from the well, said pump
S rod passageway providing a means for entry of the pump rod into the well; blow-out
prevention means contained within said central housing member, said blow-out
prevention means including a pair of rams that are adjustable to seal around the pump
rod to prevent the accidental loss or spillage of oil or fluid from the oil well; and,
pump rod passageway sealing means contained within said central housing member,
10 said pump rod passageway sealing means preventing the spillage of fluids from the
oil well upon the breakage or removal of the pump rod from said pump rod
passageway, said pump rod passageway sealing means including a valve member that
automatically seals said pump rod passageway, upon the breakage or removal of the
pump rod from the well, through the engagement of said valve member with a
15 seating member positioned in said central housing member circumferentially about
said pump rod passageway.
BR~EF DESCR~PTION OF THE DRAWINGS
20 For a better underst~n-lin~ of the present invention, and to show more clearly how
it may be carried into effect, reference will now be made, by way of example, to the
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accompanying drawings which show the preferred embodiment of the present
invention in which:
Figure 1 is a side elevational view in longitudinal section of the oil well
blow-out preventer and sealing device in accordance with the present
mvenhon;
Figure 2 is a side elevational view in longitudinal section of the blow-out
preventer and sealing device of the present invention oriented 90 degrees to
the section shown in Figure 1;
Figure 3 is a sectional view of the device of Figure 1 taken along the line 3-3;and,
Figure 4 is a sectional view of the device of Figure 1 taken along the line 4-4.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figure 1, the oil well blow-out preventer and sealing device according
20 to the present invention is noted generally by the reference numeral 1. Blow-out
preventer and sealing device 1 is constructed for use on an oil well having a well
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casing with a wellhead 2 and a production tubing string 3. A pump rod 4 passes
through, and is received within, production tubing string 3.
Device 1 is comprised generally of a central housing number S, a blow-out prevention
5 means 6, a flow passageway 42, a pump rod passageway 43 and a pump rod
passageway sealing means 7. As shown, flow passageway 42 is in communication
with production tubing string 3 and provides a means for fluid to be removed from
the well. A pump rod passageway 43 provides a means to receive and retain pump
rod 4 in that portion of the wellhead situated above production tubing string 3.
In the preferred embodiment, blow-out prevention means 6 comprises a pair of rams
8 that are adjustable to seal around pump rod 4 thereby effectively sealing off flow
passageway 42 and pump rod passageway 43 to prevent the accidental loss or spillage
of oil or fluid from the well. Typically, rams 8 would be comprised of a rubberized
15 or neoprene block of material that is generally not affected by petroleum products.
As is more clearly shown in Figure 4, rams 8 contain a longitudinal semi-circular
channel 10 on their intern~l surfaces 9. When adjusted inwardly channels 10
encompass pump rod 4 to form a tight seal around the rod.
20 Although a variety of different methods could be utilized to adjust or actuate rams
8, in the preferred embodiment, and as shown in Figures 1 and 3, rams 8 are
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adjustable inwardly or outwardly within central housing member 5 through rotating
stems 11. Stems 11 are threadably received within blow-out prevention plugs 12
which are threaded into bores 13 within central housing member 5. The inner most
ends 14 of stems 11 are attached to rams 8, but are free to rotate relative to the rams.
5 Rams 8 may therefore be moved inwardly or outwardly through threading stems 11
into or out of blow-out prevention plugs 12.
As stated, when fully adjusted inwardly, rams 8 effectively seal off flow passageway
42 and pump rod passageway 43. When adjusted oulw~dly, rams 8 are moved free
10 and clear from the flow passageways, offering no resistance to the flow from the
well. To prevent leakage of fluids to the environment a seal 15 is placed between
blow-out prevention plug 12 and central housing member 5. Typically seal 15 would
comprise an O-ring. In addition, a stem seal 16 and a stem plug 17 prevent any
leakage of fluid from between ram stems 11 and blow-out prevention plug 12.
Referring again to Figure 1, pump rod passageway sealing means 7 is contained
within an internal chamber 18 of central housing member 5. Sealing means 7
includes a rotatable valve member 19 that, in its closed position (shown in ghost
outline in Figure 1), engages a seating member 20 in pump rod passageway 43.
20 Valve member 19 is comprised of a central body 21 having a circumferential seating
base 22 for eng~ging seating member 20. Central body 21 preferably pivots about
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an axle 23 which is mounted in central housing member 5, generally perpendicular
to passageway 43. It will thus be appreciated and understood that through mounting
axle 23 generally perpendicular to pump rod passageway 43, pivotal movement of
rotatable valve member 19 about axle 23 will allow circumferential seating base 22
5 to engage seating member 20 and thereby effectively seal off pump rod passageway
43.
Pump rod passageway sealing means 7 also includes biasing means 24 that urges
rotatable valve member 19 into a position where circumferential seating base 22 bears
10 against seating member 20. In the ~refelled embodiment, and as shown in Figure 1,
biasing means 24 comprises a spring 25. Spring 25 is positioned around axle 23 and
has a pair of radially ext~n-ling spring arms 26 and 27. Spring arm 26 is received
within central body 21 of rotatable valve member 19, whereas spring arm 27 is held
in a tensioned configuration, thereby impa~ g a biasing force upon rotatable valve
15 member 19 and urging it toward seating member 20.
The amount of force necessary to rotate valve member 19, such that it fully engages
seating member 20 and forms an effective seal the,ewilh, will vary with the size of
pump rod passageway 43. For this reason spring arrn 27 is preferably biased against
20 a removable plate 28 that is received within a bore 29 e~ten~lin~ through the side of
central housing member 5. Bore 29 is preferably threaded so that a plug 30 may be
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screwed into it to retain removable plate 28 in place. It will therefore be appreciated
that through the positioning of removable plate 28 along the length of bore 29 the
degree of deflection of spring arm 27, and the resulting tensioning of spring 25, can
be adjusted. Spring arm 27 can thus be deflected to the necessary degree to ensue
that spring 25 is sufficiently tensioned to pivot rotatable valve member 19 so that it
may engage seating member 20. In the preferred embodiment, removable plate 28
is equipped with a centralized hole 31 into which the end of spring arm 27 is
received. Through the use of plates 28 having different sized holes 31, the amount
of deflection of spring arm 27 can be varied as can the biasing force which spring
25 imparts upon rotatable valve member 19. In its simplest configuration, removable
plate 28 may be a washer. Removable plate 28 also serves to hold spring arm 27 in
place during assembly of device 1.
Bore 29 and plug 30 also serve the additional function of providing an access means
32 that may be utilized during assembly or for service. If it becomes necessary to
access rotatable valve member 19, spring 25, or seating member 20, for purposes of
m~intçn~nce or replacement, an operator need only remove plug 30 and removable
plate 28 to have complete and open access to the components of pump rod
passageway sealing means 7. For example, to perform mAintenAnce on, or replace,
rotatable valve member 19 or spring 25, an operator need only adjust rams 8
inwardly such that they seal around pump rod 4, remove plug 30 and perform the
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necessary maintenance or part replacement. Accessing pump rod passageway sealing
means 7 in this manner can be accomplished without the need to remove any
additional components of the oil well. Once the maintenance has been completed,
plug 30 can be reillsell~d and rams 8 withdrawn to restore full production with little
5 down time and related costs.
Referring again to Figure 1, rotatable valve member 19 is shown to be in its normal
position when pump rod 4 is received through pump rod passageway 43 and
production tubing string 3. Under normal operating conditions, rotatable valve
10 member 19 bears against pump rod 4 such that pump rod 4 holds rotatable valve
member 19 in an open position. Figure 1 also shows that internal chamber 18 is in
direct communication with flow passageway 42 such that internal chamber 18 is filled
with production oil when the oil well is in operation. Rotatable valve member 19 is
therefore surrounded by a bath of oil which will self lubricate its point of contact
15 with pump rod 4. This self lubrication assists in reducing frictional contact between
rotatable valve member 19 and pump rod 4 to prevent wear and drag.
In the preferred embodiment of the present invention rotatable valve member 19 is
comprised of stainless steel. Forming value member 19 from stainless steel will both
20 allow for the production of a well machined and dimensioned seating base 22 and
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will provide a hard exterior surface that will be resistant to wear from coming into
contact with pump rod 4.
In an alternate embodiment, circumferential seating base 22 of rotatable valve
S member 19 may be comprised of a rubberized or neoprene material. The rubberized
or neoprene material will assist in helping to creating an effective seal between base
22 and seating member 20, and will also ensure that any wear that occurs between
rotatable valve member 19 and pump rod 4 will occur on valve member 19.
10 In operation, should pump rod 4 break or be removed from production tubing string
3, the pump rod will no longer obstruct the movement of rotatable valve member 19.
That is, upon the removal or breakage of pump rod 4. spring 25 will cause rotatable
valve member 19 to engage seating member 20 and provide a means to automatically
seal off pump rod passageway 43 to prevent the spillage of oil or fluid. When
rotatable valve member 19 seals off passageway 43 in this fashion, circumferential
seating base 22 is partially received within seating member 20 such that it "seats"
against the smooth outer lip 33 of seating member 20.
As shown in Figure I seating member 20 is threadably received within cenkal
housing member 5 thereby making it easier to produce a high quality, smooth seating
surface than would be the case if seating member 20 were an integral part of central
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housing member S. In this way seating member 20 can be removed and replaced if
it becomes damaged or worn. In the preferred embodiment seating member 20 also
includes a further sealing means 34. Typically sealing means 34 would comprise an
O-ring that provides an additional seal between circumferential seating base 22 and
5 seating member 20. It will be appreciated that where circumferential seating base 22
is comprised of stainless steel, O-ring 34 will help to prevent the leakage of fluid
upon removal or breakage of the pump rod. Depending upon the tolerances between
seating base 22 and seating member 20, O-ring 34 may in some cases act as the
primary seal against leakage. Where circumferential seating base 22 is comprised of
10 a rubberized or neoprene material, due to the flexibility of the rubberized or neoprene
matenal O-ring 34 may not be necessary or may act as a back-up seal rather than a
primary seal.
In Figures 2 and 3 it will be noted that central housing member 5 includes an internal
15 flow tee 35 that is connected to flow passageway 42 to provide a further means to
transport fluid out of the oil well. The opposing ends 36 of flow tee 35 typically
contain intçrn~l threads 37 such that distribution pipes may be screwed into ends 36
to deliver oil and fluids from the well to central collection tanks or distribution
means.
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Through the incorporation of blow-out prevention means 6, pump rod passageway
sealing means 7, and flow tee 35 into central housing member 5, the applicant has
created a compact mechanism that allows for the prevention of oil well blow-outs,
automatic sealing to prevent the spillage of oil upon the breakage or removal of a
5 pump rod, and integral means to deliver oil and fluid from the well to a centralized
holding or distribution system. The compact nature of device 1 results in a reduction
in the height of the wellhead, making access to the well and its above ground
components simpler. Furthermore, a reduction in si~ over the prior art results in a
significant weight reduction allowing for movement of device 1, its placement upon
10 the wellhead, and servicing, to be accomplished more easily and with smaller and less
costly lifting equipment.
To further facilitate in the movement of device 1, a set of internal lifting threads 38
are provided such that a lifting tool or rod can be screwed into threads 38. Finally,
15 it will also be appreciated that through the incorporation of these various primary
components within a central housing member 5, fewer connections and joints are
plcse~ d thereby reducing the potential for leakage. The lighter and more compact
central housing member also reduces the amount of torque to which an inclined or
slanted wellhead is subjected, thereby helping to reduce casing failures and stress
20 cracking.
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The versatility of device 1 is enhanced through configuring its lower end 39 to be
adaptable to a wide variety of oil well configurations. Depending upon the particular
application lower end 39 may be bolted directly to the wellhead, may be connected
to a tubing string h~nging apparatus or it may be connected to a tubing rotator.
S Where device 1 is to be used in conjunction with a tubing rotator its lower end 39
may be formed integrally with the housing of the rotator to create a single
combination al)pa~dlu~.
Since producing oil wells are rarely under constant supervision, it is often the case
10 that when a pump rod breaks it goes undetected for a length of time. A broken rod
may also be difficult to detect from a distance. For this reason, device 1 also
includes an external indication means 40 that identifies the relative position of
rotatable valve member 19. In the preferred embodiment, external indication means
40 comprises a pointer or flag 41 fixed to axle 23. In the event that pump rod 4
15 breaks thereby causing rotatable valve member 19 to engage against seating member
20, pointer or flag 41 will provide a simple and easily recognizable indication means
that will advise a technician that the rod has broken and that pump rod passageway
sealing means 7 has been automatically activated to prevent the spillage of oil or
fluid.
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It is to be understood that what has been described are the preferred embodiments of
the invention and that it is possible to make variations to these embodiments while
staying within the broad scope of the invention. Some of these variations have been
discussed while others will be readily apparent to those skilled in the art. For
5 example, while valve member 19 has been described as a rotatable value member, it
will be appreciated by those skilled in the art that it could also be comprised of a
spring actuated slide or gate value member.
