Note: Descriptions are shown in the official language in which they were submitted.
CA 02369417 2002-01-24
WATER, OIL AND GAS WELL RECOVERY SYSTEM
FIELD OF THE INVENTION
This invention relates to pump systems for use in oil, gas or water wells
and more particularly to an auto-cycling plunger for delivery of a fluid to
the
top of a well bore.
BACKGROUND OF THE INVENTION
Conventional pump systems for delivery of a fluid from a well bore
io include pump jacks or positive cavity pumps. While these pump systems have
achieved extensive use, they suffer from many disadvantages. One
disadvantage is that these systems are expensive. This is particularly
problematic for wells with low delivery rates as the cost of the equipment may
be difficult to justify. Further, these systems require the use of external
power
is or fuel for use, which requires that power, or fuel be delivered to the
well site.
Again, the cost of providing power to a well having low delivery rate may be
difficult to justify, particularly in remote well locations.
In order to overcome these problems, plunger lift systems have been
employed for the delivery of fluid from a well head using pressure from the
20 well. The fluid can include, for example, crude oil or gas. A typical
plunger in
use in a well bore has fluid above, which is being lifted from the well bore,
and
gas and fluid below, which is providing the pressure for lifting the plunger.
Early plunger lift systems include solid rods without any sealing mechanism.
The solid rod includes grooves that cause turbulence as gas passes the
25 plunger in the well bore, which aids in lifting the plunger in the bore.
These
systems are not efficient, however, as they are prone to fluid and gas leakage
past the plunger when in use. Escape of gas or fluid past the plunger causes
a loss of gas and fluid pressure from below the tool which results in slower
delivery of fluid to the top of the well bore.
30 Many variations to the plunger lift system have been proposed in an
attempt to overcome these problems. For example, U.S. Patent No.
6,148,923 to Casey, issued November 21, 2000, teaches a plunger
CA 02369417 2002-01-24
2
mechanism with a generally cylindrical body with an internal valve member
and external seals. This plunger includes a tube, a detachable valve member
that sits in the lower section of the tube and flapper sealing rings mounted
along the tube. This plunger is allowed to fall clown a well bore, the
detachable valve member separates from the cylindrical body and falls
independently through the well casing. Liquid passes through the center of
the cylindrical body as the body falls. The detachable valve member strikes a
stop in the well casing and the cylindrical body follows such that the valve
member engages in the cylindrical body and forms a seal therein. Therefore,
io the liquid below the plunger is sealed from the liquid above the plunger
and
the plunger rises as a result of the pressure below.
The system disclosed by Casey suffers many disadvantages. This
system is intended for use with a spring in the well bore for landing and
cushioning of the auto cycle plunger. This spring can break down into pieces
that can lodge in valves, flow lines or in the well bore and regular
maintenance
to avoid these problems can be costly. Also, the valve disclosed by Casey
may not function well in certain environments. Without the use of a spring,
for
example, the ball may become lodged in sand or mud in the bottom of a well
bore which may inhibit entry into the body of the plunger and prevent sealing.
Furthermore, the flapper sealing rings are all urged in the downward direction
as the plunger travels upwardly. When the head pressure rises above a
critical pressure, the flapper sealing rings are not able to maintain a seal
and
fluid can escape past these sealing rings. Thus, the system disclosed by
Casey is not effective in maintaining a seal below a perforation in a well
bore.
When the plunger is below a perforation, fluid pressure at the perforation
acts
downwardly on the plunger. If this pressure is too high, the sealing rings
will
not maintain a seal. Therefore this plunger is not effective in maintaining
seal
in a multiple perforated well bore (with more than one perforation in the well
casing for fluid ingress into the well bore).
Accordingly, it is an object of the present invention to provide a plunger
for delivery of fluid to the top of a well bore that obviates or mitigates at
least
some of the disadvantages of the prior art.
CA 02369417 2009-09-16
3
SUMMARY OF THE INVENTION
In accordance with an aspect of the present invention, there is
provided an auto-cycling plunger for use in lifting a fluid out of a well
bore.
The auto-cycling plunger for use in lifting a fluid out of a well bore, the
auto-
cycling plunger comprising.
a hollow, longitudinally extending body comprising a first end and a
second end and a tubular middle portion extending therebetween;
at least one first directional outer seal disposed on an exterior surface
of said body for creating a seal between said body and the well bore, at least
to a portion of said at least one first directional outer seal extending in a
direction substantially parallel to a length of said longitudinally extending
body such that said portion of said first directional outer seal is spread
resiliently outwardly from said body with an applied pressure, thereby
increasing the degree of sealing; and
Is a valve stem including a valve member, said valve stem extending
through said longitudinally extending body and having actuable ends
extending from said body, said valve stem operable to be shuttled between
an open position and a closed position, the valve stem including an actuating
head external to said body and proximal said first end, said actuating head
20 being of larger size than an interior diameter of said first end of said
body for
abutment therewith to prevent said stem from sliding out of said body
whereby when said valve stem is in said open position, said valve member is
longitudinally spaced from a valve seat on said body to allow fluid flow
through the length of said body and when said valve stem is in said closed
25 position, said valve member is seated on said valve seat, thereby sealing
said body and preventing fluid flow therethrough.
Advantageously, an aspect of the present invention includes a valve
member that comprises a spherical neoprene ball for striking a bottom of a
well bore. Thus, no spring is required in the well bore bottom. Also, the
30 present invention provides superior external seals for sealing the fluid
below
the pump from the fluid above the pump.
CA 02369417 2009-09-16
4
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown in the drawings
wherein:
Fig. 1 is a sectional side view of an auto-cycling plunger according to
a preferred embodiment of the invention, shown with an internal valve in an
open position;
Fig. 2 is a sectional side view of the auto-cycling plunger of Fig. 1
shown with the internal valve in a closed position;
Fig. 3 is an exploded perspective view of the auto-cycling plunger of
io Fig 1;
Fig. 4 is a partial sectional side view of the auto-cycling plunger of
Fig.1 drawn to a larger scale
Fig. 5 is a side view of the auto-cycling plunger of Fig. 1 shown with
the internal valve in the open position and the auto cycling plunger falling
in
a well bore shown in section;
Fig. 6 is a side view of the auto-cycling plunger of Fig. 5 in a bottom of
the well bore shown in section, with the internal valve in the closed
position;
Fig. 7 is a side view of the auto-cycling plunger of Fig. 6 shown rising
in the well bore shown in section; and
Fig. 8 is a side view of the auto-cycling plunger of Fig. 7 shown at a
top of the well bore, with the internal valve in the open position;
CA 02369417 2002-01-24
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Reference is first made to Figures 1 and 2 to describe a
preferred embodiment of an auto-cycling plunger designated generally by the
numeral 20. The plunger 20 includes a hollow, longitudinally extending body
5 22. At least one first directional outer seal 24 is disposed on an exterior
surface of the body 22 for creating a seal between the body 22 and a well
bore (not shown). At least a portion 28 of the at least one first directional
outer seal 24 extends in a direction substantially parallel to the length of
the
longitudinally extending body 22. The portion 28 is spread resiliently
io outwardly from the body 22 with an applied pressure, thereby increasing the
degree of sealing. The auto-cycling plunger 20 also includes a valve stem 30
including a member 36. The valve stem 30 extends through the longitudinally
extending body 22 and has actuable ends 32, 34 extending from the body 22.
The valve stem 30 is operable to be shuttled between an open position and a
is closed position. When the valve stem 30 is in the open position, shown in
Figure 1, the valve member 36 is longitudinally spaced from a valve seat 78
on the body 22 to allow fluid flow through the length of the body 22. When the
valve stem 30 is in the closed position, the valve member 36 is seated on the
valve seat 78, thereby sealing the body 22 and preventing fluid flow
20 therethrough.
Referring to Figures 1 and 2, the auto-cycling plunger 20 consists of the
body 22 and the valve stem 30. The body 22 includes a first end 38, a second
end 40 and a middle portion 42. The middle portion 42 is a hollow tubular
section with externally threaded ends for threaded engagement with the first
25 end 38 and the second end 40.
Two first directional outer seals 24, 26 are annularly disposed on the
exterior surface 44 of the tubular middle portion 42. As shown in the Figures,
one first directional outer seal 24 is located proximal the first end 38 while
the
first directional outer seal 26 is located near the center of the tubular
middle
30 portion 42. Preferably, the two first directional outer seals 24, 26 are
urethane
seals but other suitable materials can be used.
CA 02369417 2002-01-24
6
Each of the first directional outer seals 24, 26 includes a generally
cylindrical body portion 46 in sealing contact with the exterior surface 44 of
the
middle portion 42 and a flange portion, referred to herein above as portion
28.
Thus, the body portion 46 extends radially outwardly from the middle portion
42 of the body 22. The flange portion 28 extends from the body portion 46,
approximately 90 degrees from the radial direction of the body portion 46.
Therefore, the flange portion 28 extends in a direction that is substantially
parallel to the direction of the length of the longitudinally extending body
22. A
free end 48 of the flange portion 28 tapers inwardly toward the tubular middle
io portion 42 of the body 22. In the present embodiment, the body portion 46
and the flange portion 28 are continuous and are resiliently deformable.
Similar to the two first directional outer seals 24, 26, two second
directional outer seals 50, 52 are annularly disposed on the exterior surface
44 of the tubular middle portion 42. As shown in Figures 1 and 2, one second
directional outer seal 50 is located near the center of the tubular middle
portion 42 while the other of the second directional outer seals 52 is located
proximal the second end 40 of the body 22.
The two second directional outer seals 50, 52 are similar to the two first
directional outer seals 24, 26 and thus similar numerals will be used to
describe similar parts. Therefore, each of the second directional outer seals
24, 26 includes a generally cylindrical body portion 46 in sealing contact
with
the exterior surface 44 of the middle portion 42 and a flange portion 28. The
body portion 46 extends radially outwardly from the middle portion 42 of the
body 22 and the flange portion 28 extends from the body portion 46,
approximately 90 degrees from the radial direction of the body portion 46.
The flange portion 28 of the second directional outer seals 50, 52 extends in
a
direction that is substantially parallel to the direction of the length of the
longitudinally extending body 22 but substantially opposite to the direction
of
the flange portion 28 of the first directional outer seals 24, 26. Again, the
free
3o end 48 of the flange portion 28 tapers inwardly toward the tubular middle
portion 42 of the body 22.
CA 02369417 2002-01-24
7
It will now be appreciated that the first directional outer seals 24, 26 are
similar to the second directional outer seals 50, 52, however, the pump 20 is
assembled such that the flange portion 28 of the second directional outer
seals 50, 52 faces the opposite direction as the flange portion 28 of the
first
directional outer seals 24, 26.
As can be seen in Figures 1, 2 and 3, a pair of spacer elements 54
separate the first directional outer seal 24 located proximal the first end 38
from the second directional outer seal 50 located near the center of the
tubular
middle portion 42. Similarly, a pair of spacer elements 54 separate the first
io directional outer seal 26 located near the center of the tubular middle
portion
42 from the second directional outer seal 52 proximal the second end 40.
Each of the spacer elements 54 is annularly disposed around the middle
portion 42 for spacing the outer seals 24, 26, 50, 52 and maintaining their
respective positions along the middle portion 42. It will be apparent that
there
is no spacer between the first directional outer seal 26 located near the
center
of the middle portion 42 and the second directional outer seal 50 located near
the center of the middle portion 42. Thus, the first directional outer seal 26
abuts the second directional outer seal 52 and their respective flange
portions
28 are directed away from each other.
Referring to Figures 1, 2, 3 and 4, the first end 38 of the body 22 has a
large diameter section 56 with an internally threaded bore 58 sized for
threaded engagement with a threaded end of the middle portion 42. An end
wall 60 of the large diameter section 56 abuts an edge of the body portion 46
of the first directional outer seal 24. The first end 38 also has a small
diameter
section 62 that has a curved taper in the external diameter. The small
diameter section 62 also has a cylindrical passage 64 of smaller diameter than
the interior diameter of the middle portion 42 of the body 22. The cylindrical
passage 64 is sized for clearance fit with the valve stem 30.
Two opposing radial holes 66 are located in the large diameter section
56 of the first end 38. Each of the opposing radial holes 66 is partially
threaded and houses a set screw 68 that abuts a coil spring 70. Next each
coil spring 70 abuts an obround element 72 that is biased into contact with
the
CA 02369417 2002-01-24
8
valve stem 30 by the coil spring 70 and functions as part of a biased detent
system. The function of the biased detent system will be described further
below.
The larger diameter section 56 of the first end 38 also has a catch
shoulder 73 around the circumference of the large diameter section 56. The
catch shoulder 73 is sized and shaped to receive a catch in the well head
when the plunger 20 is in the well head, as will be described further below.
Referring still to Figures 1 to 4, the second end 40 of the body 22 has
an internal bore 74 that is partially threaded and is sized for threaded
io engagement with one of the threaded ends of the middle portion 42. An end
wall 76 of the second end 40 abuts an edge of the body portion 46 of the
second directional outer seal 52. On the end opposite the end wall 76, the
second end 40 includes a semi-spherical valve seat 78 longitudinally spaced
from the threaded portion of the second end 40.
Clearly the second end 40 with the internal bore 74, the tubular middle
portion 42 and the first end 38 with the internally threaded bore 58 and
cylindrical passage 64 form the continuous hollow body 22. Also, the first and
second ends 38, 40 maintain the outer seals 24, 26, 50, 52 and the spacer
elements 54 in their respective positions along the middle portion 42 by
effectively sandwiching the outer seals 24, 26, 50, 52 and spacer elements 54
therebetween.
The valve stem 30 is cylindrically shaped and includes the first and
second actuating ends 32, 34. The valve stem 30 includes a cylindrical rod 31
that is generally centrally located along an axis of the hollow body 22 and
extends past both the first and second ends 38, 40 of the body 22. The
cylindrical rod 31 is externally threaded at both ends. The actuating end 32
of
the valve stem 30 includes an actuating head 80 which is arrow-head like in
shape with a truncated tip 82. The arrow-head like shape of the actuating
head 80 allows for retrieval of the plunger 20 by hooking on to the shoulder
83
at the tip of the actuating head 80. The actuating head 80 and the shoulder
83 is also referred to as a fish neck. The actuating head 80 includes an
internally threaded bore 84 for threaded engagement with one end of the
CA 02369417 2002-01-24
9
cylindrical rod 31 and is maintained in threaded engagement with the
cylindrical rod 31 by a radially located set screw 84 threaded in the head 80
and contacting the rod 31.
The actuating end 34 of the valve stem 30 includes a spherical ball,
referred to above as the valve member 36. The spherical ball 36 is fixed to
the end cylindrical rod 31, opposite the end of the rod 31 with the actuating
head 80. The spherical ball 36 is preferably made of neoprene and includes a
hole passing therethrough. As best shown in Figure 4, a pair of nuts are
threaded onto the rod 31 with the spherical ball 36 being held on the rod 31
by
1o abutment with the nuts. The rod 31 passes through the hole in the spherical
ball 36 and at least a portion of the spherical ball 36 is sandwiched between
the nuts. The spherical ball 36 is appropriately sized and shaped to be seated
on the semi-spherical valve seat 78 of the second end 40 of the body 22.
The cylindrical rod 31 of the valve stem 30 includes a pair of
longitudinally spaced annular grooves 86, 88 appropriately sized and shaped
to receive the obround locking elements 72. The annular grooves 86, 88 are
located on the cylindrical rod 31, at a longitudinal spacing proximal the
biased
obround elements 72 such that the cylindrical rod 31 can be positioned in the
body 22 with the obround locking elements 72 in the annular groove 86
closest to the actuating end 32 or with the obround locking elements 72 in the
annular groove 88 closest to the actuating end 34 of the valve stem 30.
These positions correspond to the open position shown in Figure 1, and the
closed position shown in Figure 2. Clearly the spaced annular grooves 86, 88
are part of the biased detent system. The valve stem 30 is thereby releasably
indexed in the open and closed positions and can be shuttled therebetween.
When the valve stem 30 is in the open position, with the obround
locking elements 72 in the annular groove 86, the spherical ball 36 is
longitudinally spaced from the semi-spherical valve seat 78. In this position,
fluid can flow through the continuous hollow body 22. Conversely, when the
valve stem 30 is in the closed position, with the obround locking elements 72
in the annular groove 88, the spherical ball 36 is seated on the valve seat 78
thereby sealing the continuous hollow body 22.
CA 02369417 2002-01-24
The operation of the auto-cycling plunger 20 will now be described with
reference to Figures 1 to 8. The plunger 20 is used in a well-bore 100 for
lifting a fluid, such as oil or gas from the well and is therefore
appropriately
sized to fit in a well bore. With the valve stem 30 in the open position, the
5 plunger 20 is oriented in the well bore 100 such that the spherical ball 36
is at
the lowermost part of the plunger 20. The plunger 20 falls downwardly in the
well bore 100 and gas and fluid is free to move through the continuous hollow
body 22 and out the first end 38, as best shown in Figures 4 and 5. Fluid flow
through the plunger 20 is indicated in Figure 4.
10 When the plunger 20 reaches the bottom of the well bore 100, the
spherical ball 36 strikes the bottom and pushes the valve stem 30 upwardly.
As a result, the valve stem 30 shuttles from the open position into the closed
position shown in Figure 6. In this position, fluid can no longer flow through
the plunger 20. As would occur to one of skill in the art, fluids migrate to
the
well and cause an increase in fluid pressure below the plunger 20 in the well
bore 100. Each of the first directional outer seals 24, 26 form a seal between
the body 22 and the well bore 100. As the pressure below the plunger 20
rises, the flange portions 28 of each of the first directional outer seals are
pushed outwardly thus increasing the degree of sealing between the body 22
and the well bore 100.
It will be appreciated that the fluid above the plunger 20 imparts a
downward pressure, known as head pressure. The flange portions 28 of each
of the second directional outer seals 50, 52 are pushed outwardly thereby
forming a seal between the body 22 and the well bore 100. Thus, the fluid
below the plunger 20 is sealed from the fluid above the plunger 20. Also,
head pressure increases the degree of sealing of the plunger and maintaining
a seal in a multiple perforated well bore.
As the pressure below the plunger 20 increases, the plunger is pushed
upwardly in the well bore 100 thereby causing the fluid above the plunger 20
to rise, as shown in Figure 7. The fluid above the plunger 20 is pushed out of
the well bore 100 as the plunger 20 approaches the top of the well bore 100.
CA 02369417 2002-01-24
11
Referring to Figures 7 and 8, the well head 102 is shown, in which a
main barrel 104 is connected to and forms an extension of the well bore 100.
The well head includes the main barrel 104 and a well cap 106. As the
plunger rises, the fluid above the plunger 20 is pushed from the well head 102
and out an outflow line 108. The plunger 20 rises through the main barrel 104
and into a portion of the well cap 106. When the plunger reaches the well cap
106, the truncated tip 82 of the actuating head 80 strikes a striker plate 110
in
the well cap 106. A spring is provided at the striker plate 110 to reduce
impact
speed of the plunger 20 with the striker plate 110. Upon striking the striker
1o plate 110, the valve stem 30 shuttles from the closed position to the open
position. Meanwhile, a spring-loaded catch 112 that is radially disposed in an
upper portion of the main barrel 104 engages with the catch notch 73 of the
plunger 20. The catch 112 maintains the plunger 20 in the well head 102.
The relative positions and dimensions of the catch 112 and the striker
plate 110 are determined based on the plunger 20 dimensions. The truncated
tip 82 of the plunger 20 strikes the striker plate 110 causing the valve stem
30
to shuttle to the open position. While in this position, the catch 112 is
engaged in the catch notch 73. When the catch 112 is moved radially
outwardly, thereby disengaging the catch notch 73, the plunger 20 is free to
fall in the well bore again and repeat the cycle since fluid can again pass
through the continuous hollow body 22.
It will be appreciated that the catch 112 is used to control the cycle time
of the plunger 20. In other words, the plunger 20 can be held by the catch
112 in the well head 102 for any desired period of time. Also, the catch 112
can be automatically or manually controlled in order to control the cycling of
the plunger 20.
If desired, the plunger 20 can be retrieved or pulled from the well bore
100 by pulling on the fish neck of the actuating head 80.
While the embodiments discussed herein are directed to particular
implementations of the present invention, it will be apparent that variations
and modifications to these embodiments are within the scope of the invention
as defined solely by the claims appended hereto. For example, the size and
CA 02369417 2002-01-24
12
shape of many of the elements of the pump can vary while still performing the
same function.
