U.S. patent application number 10/656084 was filed with the patent office on 2004-03-25 for reciprocating pump dump valve.
Invention is credited to Vann, Roy R..
Application Number | 20040055743 10/656084 |
Document ID | / |
Family ID | 27761445 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040055743 |
Kind Code |
A1 |
Vann, Roy R. |
March 25, 2004 |
Reciprocating pump dump valve
Abstract
A reciprocating pump dump valve for utilization in the
hydrocarbon industry. The device is preferably used with barrel
pumps although it may be used with tubing pumps. The device is
positioned at the bottom of the wellbore immediately above the
stinger and immediately below the standing valve and allows for
complete dumping of the hydrostatic head in the production tubing
whenever the pump must be pulled.
Inventors: |
Vann, Roy R.; (Flint,
TX) |
Correspondence
Address: |
ALWORTH LAW & ENGINEERING
505 CUMBERLAND ROAD
TYLER
TX
75703-9324
US
|
Family ID: |
27761445 |
Appl. No.: |
10/656084 |
Filed: |
September 5, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10656084 |
Sep 5, 2003 |
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10374566 |
Feb 25, 2003 |
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6672393 |
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60360240 |
Feb 26, 2002 |
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60392991 |
Jul 1, 2002 |
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Current U.S.
Class: |
166/105 ;
166/332.6 |
Current CPC
Class: |
E21B 34/14 20130101;
E21B 43/127 20130101 |
Class at
Publication: |
166/105 ;
166/332.6 |
International
Class: |
E21B 043/00 |
Claims
I claim
1. A reciprocating pump dump valve utilized in hydrocarbon service
for controlling the flow of produced fluid comprising: a hollow
piston having an upper end, a lower end, an inside and an outside;
a barrel having a top, a bottom, an interior and an exterior and
adapted to slidingly receive said piston about said outside
thereof; a head having a bottom-side threadingly secured at said
bottom-side thereof to said upper end of said piston; a dump port
situated approximately midway between said top and said bottom of
said piston wherein said dump port provides communication between
said inside and said outside of said piston; and, means for
slidingly retaining said piston within said barrel; wherein said
piston is capable of limited upward and limited downward movement
within said barrel such that when said piston is fully upward said
dump port is in further communication with said exterior of said
barrel placing the dump valve in a dumping position thereby
allowing flow of produced fluid from said inside of said piston to
said exterior of said barrel and such that when said piston is
fully downward said dump port is not in communication with said
exterior of said barrel placing the dump valve in a closed position
thereby inhibiting flow of produced fluid from said inside of said
piston to said exterior of said barrel.
2. The dump valve of claim 1 wherein said piston has a
circumference and wherein said means for slidingly retaining said
piston within said barrel further comprises: a piston ring formed
about said circumference of said lower end of said piston extending
radially away from said piston; and a barrel lip formed within said
interior of said barrel approximately midway between said top and
said bottom thereof; wherein said piston ring comes to rest against
said barrel lip when said piston is fully upward thereby inhibiting
further upward movement thereof and wherein said bottom side of
said cylindrical head comes to rest against said top of said barrel
when said piston is fully downward thereby inhibiting further
downward movement thereof.
3. The dump valve of claim 1 wherein said piston has a
circumference and wherein said means for slidingly retaining said
piston within said barrel further comprises: a piston ring formed
about said circumference of said lower end of said piston extending
radially away from said piston; and a barrel lip formed within said
interior of said barrel approximately midway between said top and
said bottom thereof; a safety ring having an interior, an exterior,
a top and a bottom adapted to be slidingly received by said piston;
a safety shear pin; a safety ring safety shear pin aperture
radially formed midway between said top and said bottom of said
safety ring adapted to receive said safety shear pin and extending
from said exterior of said safety ring to said interior of said
safety ring; and, a piston safety shear pin aperture radially
formed between said upper end and said lower end of said piston
also adapted to receive said safety shear pin and extending from
said outside of said piston to said inside of said piston; such
that when said safety shear pin is inserted into said safety ring
safety shear pin aperture said safety shear pin passes into said
piston safety shear pin aperture thereby locking said safety ring
to said piston such that when said piston moves upward within said
barrel said safety ring contacts said barrel lip thereby preventing
full upward movement of said piston preventing further
communication of said dump port with said exterior of said barrel
thereby inhibiting flow of produced fluid from said inside of said
piston to said exterior of said barrel; and such that when said
safety shear pin is sheared said safety ring slides along said
piston towards said piston ring thereby allowing further upward
movement of said piston and allowing further communication between
said dump port and said exterior of said barrel placing the dump
valve in said dumping position thereby allowing flow of produced
fluid from said inside of said piston to said exterior of said
barrel; and such that when said piston is fully upward said safety
ring comes to rest between said piston ring and said barrel lip
thereby inhibiting further upward movement of said piston and
wherein said bottom side of said cylindrical head comes to rest
against said top of said barrel when said piston is fully downward
thereby inhibiting further downward movement of said piston.
4. The dump valve of claim 1 wherein said piston ring has a
midpoint and an outside and further comprising: an entry shear pin;
a piston entry shear pin aperture radially formed at said midpoint
of said piston ring adapted to receive said entry shear pin and
extending from said inside of said piston to said outside of said
piston ring; and, a barrel entry shear pin aperture radially formed
near said bottom of said barrel also adapted to receive said entry
shear pin and extending from said interior of said barrel to said
exterior of said barrel; such that when said entry shear pin is
inserted into said barrel entry pin aperture said entry shear pin
passes into said piston entry pin aperture thereby locking said
piston in an entry position wherein a fixed distance is maintained
between said lower end of said head and said top of said barrel
thereby preventing further communication of said venting port with
said exterior of said barrel thereby inhibiting flow of produced
fluid from said inside of said piston to said exterior of said
barrel.
5. The dump valve of claim 3 wherein said piston ring has a
midpoint and an outside and further comprising: an entry shear pin;
a piston entry shear pin aperture radially formed at said midpoint
of said piston ring adapted to receive said entry shear pin and
extending from said inside of said piston to said outside of said
piston ring; and, a barrel entry shear pin aperture radially formed
near said bottom of said barrel also adapted to receive said entry
shear pin and extending from said interior of said barrel to said
exterior of said barrel; such that when said entry shear pin is
inserted into said barrel entry pin aperture said entry shear pin
passes into said piston entry pin aperture thereby locking said
piston in an entry position wherein a fixed distance is maintained
between said lower end of said head and said top of said barrel
thereby preventing further communication of said dump port with
said exterior of said barrel thereby inhibiting flow of produced
fluid from said inside of said piston to said exterior of said
barrel.
6. The dump valve of claim 1 further comprising sealing means
between said outside of said piston and said interior of said
barrel.
7. The dump valve of claim 5 further comprising sealing means
between said outside of said piston and said interior of said
barrel.
8. The dump valve of claim 3 further comprising a hold-open spring
inserted at said lower of said piston and within said interior of
said barrel at the bottom thereof, said hold-open spring being
retained whenever the dump valve is attached to a hold-down stinger
such that whenever said safety shear pin is sheared said hold-open
spring expands upwards thereby holding the dump valve in the dump
position.
9. The dump valve of claim 5 further comprising a hold-open spring
inserted at said lower of said piston and within said interior of
said barrel at the bottom thereof, said hold-open spring being
retained whenever the dump valve is attached to a hold-down stinger
such that whenever said safety shear pin is sheared said hold-open
spring expands upwards thereby holding the dump valve in the dump
position.
10. A reciprocating pump dump valve utilized in hydrocarbon service
for controlling the flow of produced fluid comprising: a hollow
piston having an upper end, a lower end, an inside and an outside;
a barrel having a top, a bottom, an interior and an exterior and
adapted to slidingly receive said piston about said outside
thereof; a head having a bottom-side threadingly secured at said
bottom-side thereof to said upper end of said piston; a dump port
situated approximately midway between said top and said bottom of
said piston wherein said dump port provides communication between
said inside and said outside of said piston; a piston ring formed
about said circumference of said lower end of said piston extending
radially away from said piston having a midpoint and an outside; a
barrel lip formed within said interior of said barrel approximately
midway between said top and said bottom thereof, a safety ring
having an interior, an exterior, a top and a bottom adapted to be
slidingly received by said piston; a safety shear pin; a safety
ring safety shear pin aperture radially formed midway between said
top and said bottom of said safety ring adapted to receive said
safety shear pin and extending from said exterior of said safety
ring to said interior of said safety ring; and, a piston safety
shear pin aperture radially formed between said upper end and said
lower end of said piston also adapted to receive said safety shear
pin and extending from said outside of said piston to said inside
of said piston; an entry shear pin; a piston entry shear pin
aperture radially formed at said midpoint of said piston ring
adapted to receive said entry shear pin and extending from said
inside of said piston to said outside of said piston ring; and, a
barrel entry shear pin aperture radially formed near said bottom of
said barrel also adapted to receive said entry shear pin and
extending from said interior of said barrel to said exterior of
said barrel; such that when said entry shear pin is inserted into
said barrel entry pin aperture said entry shear pin passes into
said piston entry pin aperture thereby locking said piston in an
entry position wherein a fixed distance is maintained between said
lower end of said head and said top of said barrel thereby
preventing further communication of said dump port with said
exterior of said barrel thereby inhibiting flow of produced fluid
from said inside of said piston to said exterior of said barrel;
and such that when said safety shear pin is inserted into said
safety ring safety shear pin aperture said safety shear pin passes
into said piston safety shear pin aperture thereby locking said
safety ring to said piston such that when said piston moves upward
within said barrel said safety ring contacts said barrel lip
thereby preventing full upward movement of said piston preventing
further communication of said dump port with said exterior of said
barrel thereby inhibiting flow of produced fluid from said inside
of said piston to said exterior of said barrel; and such that when
said safety shear pin is sheared said safety ring slides along said
piston towards said piston ring thereby allowing further upward
movement of said piston and allowing further communication between
said dump port and said exterior of said barrel placing the dump
valve in said dumping position thereby allowing flow of produced
fluid from said inside of said piston to said exterior of said
barrel; and such that when said piston is fully upward said safety
ring comes to rest between said piston ring and said barrel lip
thereby inhibiting further upward movement of said piston and
wherein said bottom side of said cylindrical head comes to rest
against said top of said barrel when said piston is fully downward
thereby inhibiting further downward movement of said piston; and,
wherein said piston is capable of limited upward and limited
downward movement within said barrel such that when said piston is
fully upward said dump port is in further communication with said
exterior of said barrel placing the dump valve in a dumping
position thereby allowing flow of produced fluid from said inside
of said piston to said exterior of said barrel and such that when
said piston is fully downward said dump port is not in
communication with said exterior of said barrel placing the dump
valve in a closed position thereby inhibiting flow of produced
fluid from said inside of said piston to said exterior of said
barrel.
11. The dump valve of claim 10 further comprising sealing means
between said outside of said piston and said interior of said
barrel.
12. The dump valve of claim 10 further comprising a hold-open
spring inserted at said lower of said piston and within said
interior of said barrel at the bottom thereof, said hold-open
spring being retained whenever the dump valve is attached to a
hold-down stinger such that whenever said safety shear pin is
sheared said hold-open spring expands upwards thereby holding the
dump valve in the dump position.
13. A reciprocating pump dump valve positioned below the standing
valve assembly but above the stinger assembly of a reciprocating
pump placed within the production tubing of a well for controlling
the flow of produced fluid comprising: a hollow piston having an
upper end, a lower end, an inside and an outside; a barrel having a
top, a bottom, an interior and an exterior and adapted to slidingly
receive said piston about said outside thereof; a head having a
bottom-side threadingly secured at said bottom-side thereof to said
upper end of said piston; a dump port situated approximately midway
between said top and said bottom of said piston wherein said dump
port provides communication between said inside and said outside of
said piston; a piston ring formed about said circumference of said
lower end of said piston extending radially away from said piston
having a midpoint and an outside; a barrel lip formed within said
interior of said barrel approximately midway between said top and
said bottom thereof; a safety ring having an interior, an exterior,
a top and a bottom adapted to be slidingly received by said piston;
a safety shear pin; a safety ring safety shear pin aperture
radially formed midway between said top and said bottom of said
safety ring adapted to receive said safety shear pin and extending
from said exterior of said safety ring to said interior of said
safety ring; and, a piston safety shear pin aperture radially
formed between said upper end and said lower end of said piston
also adapted to receive said safety shear pin and extending from
said outside of said piston to said inside of said piston; an entry
shear pin; a piston entry shear pin aperture radially formed at
said midpoint of said piston ring adapted to receive said entry
shear pin and extending from said inside of said piston to said
outside of said piston ring; and, a barrel entry shear pin aperture
radially formed near said bottom of said barrel also adapted to
receive said entry shear pin and extending from said interior of
said barrel to said exterior of said barrel; such that when said
entry shear pin is inserted into said barrel entry pin aperture
said entry shear pin passes into said piston entry pin aperture
thereby locking said piston in an entry position wherein a fixed
distance is maintained between said lower end of said head and said
top of said barrel thereby preventing further communication of said
dump port with said exterior of said barrel thereby inhibiting flow
of produced fluid from said inside of said piston to said exterior
of said barrel; and such that when said safety shear pin is
inserted into said safety ring safety shear pin aperture said
safety shear pin passes into said piston safety shear pin aperture
thereby locking said safety ring to said piston such that when said
piston moves upward within said barrel said safety ring contacts
said barrel lip thereby preventing full upward movement of said
piston preventing further communication of said dump port with said
exterior of said barrel thereby inhibiting flow of produced fluid
from said inside of said piston to said exterior of said barrel;
and such that when said safety shear pin is sheared said safety
ring slides along said piston towards said piston ring thereby
allowing further upward movement of said piston and allowing
further communication between said dump port and said exterior of
said barrel placing the dump valve in said dumping position thereby
allowing flow of produced fluid from said inside of said piston to
said exterior of said barrel; and such that when said piston is
fully upward said safety ring comes to rest between said piston
ring and said barrel lip thereby inhibiting further upward movement
of said piston and wherein said bottom side of said cylindrical
head comes to rest against said top of said barrel when said piston
is fully downward thereby inhibiting further downward movement of
said piston; and, wherein said piston is capable of limited upward
and limited downward movement within said barrel such that when
said piston is fully upward said dump port is in further
communication with said exterior of said barrel placing the dump
valve in a dumping position thereby allowing flow of produced fluid
from said inside of said piston to said exterior of said barrel and
such that when said piston is fully downward said dump port is not
in communication with said exterior of said barrel placing the dump
valve in a closed position thereby inhibiting flow of produced
fluid from said inside of said piston to said exterior of said
barrel.
14. The dump valve of claim 13 further comprising sealing means
between said outside of said piston and said interior of said
barrel.
15. The dump valve of claim 13 further comprising a hold-open
spring inserted at said lower of said piston and within said
interior of said barrel at the bottom thereof, said hold-open
spring being retained whenever the dump valve is attached to a
hold-down stinger such that whenever said safety shear pin is
sheared said hold-open spring expands upwards thereby holding the
dump valve in the dump position.
Description
[0001] This application claims priority from Provisional Patent
Application No. 60/360,240 filed on Feb. 26, 2002 and Provisional
Patent Application No. 60/392,991 filed on Jul. 1, 2002 and is a
divisional application of U.S. patent application Ser. No.
10/374,566 filed on Feb. 25, 2003.
[0002] The present invention relates generally to the oil and gas
industry: in particular to oil well production utilizing
reciprocating pumps and the servicing of same.
BACKGROUND OF THE INVENTION
[0003] Oil wells are produced using a variety of methods ranging
from self-production, where the formation pressure is high enough
to cause the oil to flow up the wellbore, to various forms of
artificial lift, where the formation pressure is insufficient and
cannot lift the hydrocarbon fluid up the wellbore. The most common
artificial form used in the oil industry is the reciprocating
pump.
[0004] The standard industry reciprocating pump consists of a prime
mover that is positioned at the surface, and a pumping barrel that
is positioned within the production tubing at or near the bottom of
the wellbore. The wellbore is lined with steel pipe called
casing.
[0005] The production tubing is concentric within the casing and is
the conduit through which produced fluids are sent to the surface.
The area between the production tubing and the casing (wellbore) is
called the annulus. The production tubing is generally suspended
from the surface and "rests" against the casing forming a seal at
the surface. The steel casing has a series of holes or perforations
punched in the casing where the producing formation is found, that
allow the formation fluid to enter the annulus.
[0006] The production tubing has a "seating nipple" at the
formation end of the tubing into which the pump will seat. The
tubing may be terminated in a rounded end with a series of
perforations that act as a course filter and allow the formation
fluid to enter the production tubing. The seating nipple has a
reduced inside diameter when compared to the tubing that forms a
hold-down into which the pump barrel locks or is held-down. The
barrel is locked into place within the production tubing so that a
seal is formed between the pump and the production tubing. This
seal keeps the produced fluid from re-entering the formation.
[0007] There are two ways by which the pump at the end of the
production tubing is driven (reciprocated). The first uses the
industry standard sucker rods, and the second uses a new technique
that employs a wire cable. Both the cable and the sucker rod string
terminate at the pump and at the prime mover. A cable driven pump
will employ the same (or similar) pull rod at the downhole end.
Thus, the sucker rod string in a sucker rod driven pump and the
cable in a cable driven pump terminate in the pull rod.
[0008] After a period of time, the downhole pump must be serviced,
and the cable or sucker rod string is employed to lift the pump up
and out of the well. The pump is pulled up to the surface within
the production tubing. A certain amount of force is required to
"pop" the pump loose from the hold-down at the bottom of the
production tubing.
[0009] Very often the force to "pop" the pump loose is excessive
and is caused by "flower sand" buildup around and about the pump at
the hold-down. Flower sand is entrained in the produced fluid and
tends to precipitate from the fluid as it passes up the production
tubing. The sand then falls to the bottom of the tubing and "packs"
around the hold-down thereby substantially increasing the force
required to "pop" the pump loose from the hold-down.
[0010] Further more because there are series of ball and check
valves within the pump, the initial force required to "pop" the
pump loose must also pull against the hydrostatic head contained
within the production tubing which thereby increases the required
unseating force. As the depth of the well increases, the weight of
the produced fluid increases: essentially, the weight of produced
fluid is related to the hydrostatic head contained within the
production tubing. As soon as the pump pops loose the hydrostatic
head will reduce because the fluid in the production tubing will
U-tube within the annulus and tubing.
[0011] There have been instances when the sucker rod string breaks,
due to the high force required to "pop" the pump loose, thus
leaving the pump in the tubing. At this point, the well operator
must pull the production tubing to retrieve the pump: an expensive
operation. In the case of the wire cable driven pump, the wire
cable is often limited in pulling force, and the tubing would have
to be pulled.
[0012] Among some of the prior art attempting to solve the problem
caused by sand buildup and hydrostatic head are: Hall (U.S. Pat.
Nos. 5,018,581 and 4,103,739), Hix (U.S. Pat. No. 3,994,338), Howe
(U.S. Pat. No. 3,150,605), Owen (U.S. Pat. No. 4,909,326),
Sonderberg (U.S. Pat. No. 4,645,007) and Sutliff et al. (U.S. Pat.
No. 4,273,520. Hall envisions an auxiliary valve-like device that
is placed at some point (mid) in the pump barrel as the barrel is
being made up. This valve opens during withdrawal of the pump if
the pulling force exceeds a predetermined force caused by sand
buildup. If the device does not open, then it is assumed there is
no sand buildup and the device may be re-inserted into the
wellbore.
[0013] Hix describes a frangible rupture disk that is placed
between the standing valve and the hold down in a barrel pump
assembly. The rupture disk is activated by increasing the pressure
in the standing column of produced fluid; thus, some sort of
pumping device is required at the surface. The device also
incorporates a left hand thread that allows the pump to be
unscrewed if the rupture disk fails to rupture. This is a one shot
device.
[0014] Howe illustrates a complex ball and seat device that is
placed at the pump head and drains the tubing fluid above and
around the pump whenever the pump is raised out of the tubing. It
does not release the hydrostatic head in the tubing.
[0015] Owen portrays a tubing unloader that is placed in the tubing
itself As the tubing is pulled upward the unloader opens and allows
the entrapped fluid to drain back into the annulus.
[0016] Sonderberg also describes a tubing unloader that is placed
in the tubing like the device of Owens. However, the Sonderberg
device uses an increase in fluid pressure to open the device. Again
this implies some sort of pump source at the surface. Finally,
Sutliff et al. disclose a deep well pump that incorporates a drain
valve that allows the pump to drain within the tubing so that the
pump is basically pulled dry from the well.
[0017] The industry has attempted to solve the flower sand problem
by using a bottom discharge valve mounted below the pump, but above
the lower check valve (stationary valve), that allows back flow of
produced fluid, thereby causing a swirl that hopefully picks up the
sand about the hold-down reducing the force required to "pop" the
pump loose. The valve which is really a second check valve that, on
the downstroke, allows flow of produced fluid from the pump barrel
into the tubing (Note the valve is spring loaded so that downward
force is required to force the produced fluid backwards into the
tubing.) The by-passed flow causes a swirl around the bottom
section of the pump and up into the tubing. The device helps but,
because it is located away from the hold-down, it is somewhat
inefficient when washing sand. The force required to push the fluid
through the bottom discharge valve is supplied by the weight of the
sucker rod string (coupled through the pull rod). The required
force ("weight") is unavailable in a cable driven pump. ("One
cannot push on a rope.") The industry has not resolved the
hydrostatic head problem.
[0018] Thus, there remains a need for a device that will wash the
flower sand buildup from about the hold-down within the production
tubing and/or reduce hydrostatic head, thereby reducing the force
required to "pop" a pump loose for servicing. The need is even
higher for cable driven pumps.
SUMMARY OF THE INVENTION
[0019] The prototype device is about 12 inches long, consists of
three major parts and would be run between the ball and seat and
the hold down (stinger) prior to being placed in the wellbore. The
first part is the outer barrel that attaches to a standard
hold-down stinger. The second part is a hollow moving piston within
the barrel. The third part is header that attaches to the piston
and to the bottom of the pump barrel immediately below the ball and
seat. Produced fluid normally flows from the hold-down stinger,
through the hollow piston, through the header, and into the ball
and seat assembly associated with the pump.
[0020] The piston has a set of apertures, called dump aperture(s)
or dump port(s), and a series of seal O-rings. The O-rings and
apertures remain within the barrel until activated by forces
applied from the surface. The dump port(s), if exposed from within
the barrel, will allow fluid to flow from the hollow aperture.
[0021] The device has three "positions." These positions are the
entry position, the cocked closed or safety position and the dump
position. The entry position is the initial position and is kept in
this position by an entry shear pin or a set of entry shear pins.
In the entry position, the header is approximately 1/2-inch above
the barrel. At the same time the "dump" port(s) remain(s) "locked"
within the barrel. No fluid can pass from within the hollow piston
and the outside of the barrel. Produced fluid only flows from the
formation into the pump and onto the surface.
[0022] Allow some time to pass and require that the pump be served.
The operator allows the reciprocating system to drive the device
downwards toward the bottom of the well. This action shears the
"entry" shear pin(s) and allows the header to come into contact
with the barrel. The device is now "cocked" in that it may be
opened. The operator then draws up on the reciprocating system
causing the piston to move upwards within the barrel towards the
top of the device. Additional upward force is required to shear the
"safety-pin(s)" within the barrel. This then allows the piston to
move further upward exposing the "dump port(s)" that allow(s) for
reverse flow. The reverse flow will allow the hydrostatic head to
dissipate into the annulus, and, if required, wash flower sand from
around the hold-down; thereby, reducing the total pull required to
"pop" the pump loose and withdraw it from the well.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a cross-sectional view of the barrel of the
instant device showing the entry shear pin.
[0024] FIG. 2 is a cross-sectional view of the piston, safety ring
and head of the instant device showing the safety shear pin.
[0025] FIG. 3 is a cross-sectional view of the instant device in
its "entry" position.
[0026] FIG. 4 is a cross-sectional view of the instant device after
being taken out of entry or in its "cocked" position.
[0027] FIG. 5 is a cross-sectional view of the instant device in
its "dump" position and ready to come out of the well.
[0028] FIG. 6 is a simplified illustration of a wellbore showing
the production tubing, a series of sucker rods terminating in a
pull rod that is connected to a pump plunger that in turn operates
within a pump barrel, and the instant invention connected at the
bottom of the pump barrel.
[0029] FIG. 7 is a cross-sectional view of a fishing neck
attachment used in tubing pump applications.
[0030] FIG. 8 is a cross-sectional view of the instant device in
its "dump" position, showing the spring designed to hold the device
in its dump position.
DETAILED DESCRIPTION OF THE EMBODIMENT
[0031] The device disclosed may be used in conjunction with tubing
pump method, stationary pump barrel method, traveling barrel pump
method, and other pumping methods that require a standing valve.
The oil industry generally defines a standing valve as a valve that
causes produced fluid to "stand" in the production tubing. When
used in pumping operations, the standing valve is a check valve
(usually one or more ball and seat valves) that allows for the
one-way passage of produced fluid from the formation to the
surface.
[0032] The tubing pump method is probably the most common method of
pumping. In the past, when using the tubing pump method, and prior
to beginning pumping operations, a standing valve is dropped from
the surface to seat into a standard seating nipple located at the
bottom of the production tubing. This standing valve provides a
means to apply pressure down the tubing to check its integrity and
to check the seal the ball and seat, prior to inserting the tubing
pump and beginning pumping operations.
[0033] A minor change in standard procedure is employed when using
the instant device with a tubing pump. The instant device is first
attached to a standard stinger and standing valve, and the assembly
is dropped down the tubing so that the device comes to rest in the
seating nipple with the standing valve located on top. The complete
assembly now provides a means to apply pressure down the tubing to
check its integrity and to check the seal the ball and seat, prior
to inserting the tubing pump and beginning pumping operations. (It
may not be necessary to run the safety or entry shear pins in the
instant device, as will be explained.) Optionally a fish neck (FIG.
7) may be attached to the standing valve.
[0034] Typically in the tubing pump method, the standing valve
assembly is not retrieved unless the tubing needs to be pulled. If
the tubing needs to be pulled, the recommended procedure, which is
commonly practiced today when rods are run, is to lower the sucker
rod string assembly and thread onto (by rotation) the standing
valve and pull up until assembly is released from seating nipple.
This sometimes requires a large amount of tension due to
hydrostatic and friction forces. As will be explained, the present
invention allows the dumping of fluid prior to releasing the hold
down from the seating nipple, which will make retrieval easier.
[0035] As can be readily expected, the sucker rods allow for
sufficient force to be transmitted down the tubing to the standing
valve allowing the standing valve to be pulled upwards against the
hydrostatic head, friction forces and seating force thereby
removing the valve from the tubing. The removal of the standing
valve allows the production tubing to drain as the tubing is later
pulled. When a cable pump is used with the tubing pump method the
cable cannot transmit sufficient force to the standing valve to
overcome the hydrostatic head, friction forces and seating force.
Therefore the assembly, described above, of the instant device and
a standard standing valve must be employed. When the assembly is
used, the cable and special retrieval tool (see FIG. 7) is used to
open the dump valve, thereby dumping the fluid in the production
tubing and then pulling the entire assembly from seating
nipple.
[0036] The instant device can also be applied to other pumping
methods such as the "traveling" barrel pump system and the
"stationary" barrel pump system using similar installation methods.
The former system reciprocates to recover fluid on the downstroke
whereas the latter system reciprocates to recover fluid on the
upstroke. In the barrel pump application the device is attached to
the bottom of the standing valve that is attached to the pump. The
pump barrel, the instant device, the standing valve and the pump
are then "run" (a term of art meaning place into a well) on same
trip in a well.
[0037] In most pump methods where a standing valve is run prior to
running pump assembly and/or the invention is run while running a
pump barrel on the same trip in well, and when the invention is run
and operated as intended, the pulling of a "wet string" should be
eliminated and ease of removal from the seating nipple should be
enhanced.
[0038] Referring to FIG. 6, the instant invention, the dump valve,
10, which is cylindrical in overall shape is shown in place on a
standard art reciprocating pump, 102, as currently used in the
industry (with a stationary barrel). The description of the
embodiments of the instant device will use a stationary barrel
pump; however, the instant device will operate with a reciprocating
barrel or tubing pump as explained above. Shown in the drawing are
the usual standard pull rod, 104, and sucker rod string, 105. The
instant device, 10, is located immediately below the standing (ball
and seat) valve assembly of the pump, 101, and screws into the
standing (ball and seat) valve assembly. The valve cage or stinger,
100, that also interlocks with the seating nipple on the production
tubing, screws into the bottom of the instant device. Also shown is
the optional upper standing head valve, 103, that is the subject of
U.S. Pat. No. 6,382,244 to the present inventor. The upper standing
head valve is designed to keep the wellbore (fluid within the
production tubing) hydrostatic head away from the formation.
[0039] The instant device consists of three basic parts, the
barrel, 1; the head, 3; and the piston, 2; plus several ancillary
parts. The ancillary parts are the safety ring, 4; the safety shear
pin, 6; the entry shear pin(s), 7; three piston O-rings, 8, and one
optional safety ring O-ring, 9, that are placed in associated
O-ring grooves located on the piston and/or safety ring.
[0040] Referring to FIG. 2, the head, 3, is shown screwed onto the
piston, 2, the reason that these two parts screw together will
become apparent later. Located on the piston are a series of O-ring
grooves, 23, 24, and 25. These grooves accept O-rings, 8, as shown
in FIG. 3 through FIG. 5.
[0041] The piston fits (or slides) within a barrel, 1, shown in
FIGS. 3-5. Located near the bottom of the barrel is the Barrel
Entry Pin aperture, 12, which accepts the Entry Shear Pin(s), 7,
(when employed). Located at the bottom of the barrel are threads,
13, which accept a standard valve cage or stinger, 100 (see FIG.
6).
[0042] FIG. 3 shows the instant device, 10, in its initial, or
safety, assembled position. The device is assembled by placing the
safety ring, 4, on the piston, 2, and pinning it in place with the
safety shear pin, 6. The safety shear pin passes through the safety
ring pin aperture, 41, and the piston safety ring pin aperture, 26.
An optional dump ring O-ring, 9, is placed in the optional
corresponding groove, 42, on the safety ring. This O-ring is
optional and may be left out of the assembly. It is preferred
because the O-ring aids in piston assembly and movement of the
safety ring within the barrel (stops galling). Further the O-ring
may help prevent fluid by-pass if the safety ring shear pin is not
tight within the corresponding aperture(s).
[0043] The assembly operation is continued by placing O-rings, 8,
in the corresponding groves on the piston and inserting the piston,
2, into the barrel, 1, from the bottom of the barrel. The entry
shear pin(s), 7, is (are) then inserted through the barrel entry
pin aperture, 12, and into the piston entry pin aperture, 26,
located in the piston ring, 21, at the midpoint between the top and
the bottom of the ring. The head, 3, is then screwed onto the
piston. The resulting "entry" assembly is shown in FIG. 3. Tool
groves are provided on the barrel, the piston and the head so that
the threads may be made up to proper torque limits without placing
a strain on the shear pins.
[0044] The device is installed on a standard downhole reciprocating
pump and inserted into the production tubing using standard
industry techniques as shown in FIG. 6. In the "entry" position,
the O-rings in the upper set of O-ring grooves, 23 and 24, inhibit
fluid flow between the inside of the piston and the annulus. FIGS.
3 through 5 show the instant device in its three respective
operating positions, entry, cocked closed and dump, as will be
explained.
[0045] The "entry-position" (as shown in FIG. 3) is not one hundred
percent necessary and the step (or position) may be left out;
however, practical experience dictates the need for an "entry
position." It is known that insertion of a pump into a wellbore is
fraught with difficulty--no wellbore is straight! Thus, while
inserting the pump into the wellbore it may be necessary to
reciprocate and rotate the entire string (pump and rods) when the
pump hangs up in the wellbore. The entry position allows for
movement of the string without shearing the safety shear pin (as
will be explained) which is designed to shear at considerably less
force than the entry pin(s). Thus, the force required to shear the
entry pin (or pins) is set much higher than the force to shear the
safety pin because the hydrostatic head will assist in providing
the required shear force. (More than one entry shear pin may be
required and the number of pins will be set by the required shear
force and is easily determined by one skilled in the art.) The
fixed entry position allows the operator to move the pump and
device up and down (and rotate) thereby helping the pump enter the
wellbore.
[0046] To remove the pump from the wellbore, the reciprocating pump
sucker rod string or the cable, is lowered further into the
wellbore. This operation causes additional weight to be applied to
the device, in turn causing the piston to want to move down thereby
shearing the entry shear pin(s), 7 (if not already inadvertently
sheared). The force applied to the shear pin will equal the
hydrostatic head plus the weight of the pump and associated rods.
The shear pin(s) is (are) designed to shear at a predetermined
pressure OVER the hydrostatic head pressure.
[0047] It should be noted that the force required to shear the
entry pin(s) is readily supplied by the total weight of the sucker
rods 105, pull rod, 104, and pump, 102, in a sucker rod driven
pump. This is not the case in a cable driven pump and additional
sinker (weight) rods may have to be attached between the pull rod
and the cable. Careful choice of the safety shear force and known
hydrostatic head may remove the need for additional weight rods in
a cable driven pump.
[0048] The device is now out of its "entry" position and is ready
to operate (see FIG. 4). The rod string or cable is now further
withdrawn thereby shearing the safety shear pin, 6, allowing the
piston to move to its "dump" position as shown in FIG. 5. The
safety ring, 4, sides along the piston and comes to rest against
the safety ring, 31, and against the barrel lip, 14; thereby
retaining the piston within the barrel. This action exposes the
dump port or aperture, 5, that allows fluid in the production
tubing to "dump" back into the annulus further washing sand and
dumping the hydrostatic head above the pump, 102. The dump port is
sized according to hydrostatic head and required dump time. A
typical value would be {fraction (3/16)}-inch and a plurality of
such apertures may be employed.
[0049] The only force that must now be used to remove the pump from
within the production tubing is the force required to "pop" the
valve cage free of the seating nipple. Thus the device acts to
reduce the overall force that must be exerted thereby facilitating
ready removal of the pump and reducing the chance that the entire
production tubing must be removed.
[0050] As explained earlier the instant device may also be employed
in tubing pumps. The bottom of the device is attached to the valve
cage or stinger and the upper end is attached to the tubing pump
standing valve. The standing valve in turn is attached to a
retrieving collar (typically shown in FIG. 7) if wire line
techniques are to be used. The entire assembly is then dropped down
the production tubing and standard operating procedures are then
followed. I.e., the well is pressure tested, the tubing pump is run
down the tubing and the pump started.
[0051] Now allow that the entire tubing must be retrieved. The
tubing pump would first be withdrawn. If the entry position shear
pins are not employed, then standard wireline fishing techniques
are employed and a fish is run down the tubing, which attaches
(with luck) to the fishing neck. The line is pulled upwards
shearing the safety pin(s) and placing the instant device in the
dump position, The entire assembly is then removed from the tubing
and the tubing is then retrieved. It should be noted that with a
cable pump system, the cable itself will serve as a wireline
thereby saving the cost of a wireline service provider.
[0052] Alternately, after the pump is withdrawn, standard sucker
rods techniques (with or without the entry pins in place) may be
used to pull the downhole dump valve to the dump position following
the descriptions already given.
[0053] The inventor has an interesting alternate embodiment of the
instant device, namely a "one-shot"--dump and forget--device, using
a single additional spring, that will be described. When the device
is being made up, a suitable spring, 99, is placed at the bottom of
the device between the bottom of the piston, 2, and the stinger,
100. (See FIG. 8.) The stinger serves to hold the spring in place
and loaded against the piston. The entry shear pin(s), if employed
and the safety pin serve to keep the dump valve closed. Thus, when
the dump valve is pulled to its dump position (by any of the
techniques described) the spring will hold the dump valve open once
the hydrostatic head dissipates. This embodiment will find great
use when wire line techniques are used to open the valve in a
tubing pump application.
[0054] After the tubing pump is removed and if the tubing is to be
retrieved, standard wireline techniques are employed to open the
valve via the fishing neck as previously described. However, the
entire assembly is not retrieved --just opened and held open until
the hydrostatic head dissipates. The wireline is then released and
withdrawn. The tubing string may then be pulled with the dump valve
spring loaded in the dump position.
[0055] There has been described the preferred and best modes for
the instant device and methods of use. The choice of metals has not
been specified and would be set by standard industry conditions and
choices. The size of the dump ports or apertures is typical and a
plurality of such apertures may be employed. Standard techniques
for sizing shear pins are employed and the entry shear pin may have
to be increased to a plurality in order to obtain a desired shear
force. For example 0.159-inch one-half hard brass is used for both
prototype shear pins. If the entry position is not used, the force
to shear safety shear pin may be increased and a plurality of such
pins may be required. Such a step is anticipated by this
disclosure. Finally, the number of O-rings (and associated grooves)
is a matter of choice and may be increased or decreased. Such
action is anticipated by this disclosure.
* * * * *