U.S. patent application number 10/077034 was filed with the patent office on 2003-08-21 for plunger with novel sealing.
Invention is credited to Gray, William R., Holt, James H..
Application Number | 20030155129 10/077034 |
Document ID | / |
Family ID | 27732572 |
Filed Date | 2003-08-21 |
United States Patent
Application |
20030155129 |
Kind Code |
A1 |
Gray, William R. ; et
al. |
August 21, 2003 |
Plunger with novel sealing
Abstract
A plunger for use in downhole tubulars in wells which produce
fluids and/or gases under variable pressure. The plunger is
slidingly engageable within the tubulars and capable of movement up
and down the tubulars, and has a jacket comprised of segments
mounted about a core which have sealing, holding, and lifting
capabilities. An inner turbulent or labyrinth-type seal is
accomplished by circumferential grooves on the core and/or fingers
which project inwardly from the underside of the segments. When the
pressure inside the tubulars above the plunger is reduced, the
plunger and fluids move upwardly to the surface.
Inventors: |
Gray, William R.;
(Huntsville, TX) ; Holt, James H.; (Conroe,
TX) |
Correspondence
Address: |
THE MATTHEWS FIRM
Suite 1800
1900 West Loop South
Houston
TX
77027
US
|
Family ID: |
27732572 |
Appl. No.: |
10/077034 |
Filed: |
February 15, 2002 |
Current U.S.
Class: |
166/370 ;
166/106; 166/68 |
Current CPC
Class: |
E21B 43/121
20130101 |
Class at
Publication: |
166/370 ;
166/106; 166/68 |
International
Class: |
E21B 043/18 |
Claims
1. A plunger for use in a gas/fluid lift system in downhole
tubulars in wells producing fluids and/or gases under variable
pressures, comprising: a body slidingly engageable within the
tubulars and capable of movement up and down said tubulars; said
body having a top end and a bottom end; an inner core within the
body for internal sealing; a flexible jacket having plurality of
segments mounted about said core, each of said segments having a
convex outer surface and an inner surface, first and second sides,
and top and bottom ends; said jacket having an inner surface
providing an internal seal, and an outer surface being radially
expandable to provide an external seal against the interior of said
tubulars; a flow path for fluids and/or gases between said core and
the inner surface of said jacket; wherein each of said internal and
external seals retards the upward flow of fluids and/or gases which
thereby increases pressure below the plunger to thereby move the
plunger and accumulated well fluids upwardly to the surface when
the pressure inside the tubulars above the plunger is reduced.
2. The plunger of claim 1, wherein the inner surface of each said
segment has at least one rigid finger protruding radially inward
toward the core, with the finger of each said segments cooperating
to encircle the core and being separated from the core unless the
fingers are pushed to their most inward position.
3. The plunger of claim 2, wherein the finger has a flat bottom
side and a flat top side, a curved concave inner surface, and first
and second sides which are flat and angularly aligned with the side
edges of the adjacent segments.
4. The plunger of claim 1, having at least one circumferential
groove in the surface of the core.
5. The plunger of claim 2, having at least one circumferential
groove in the surface of the core, wherein the finger is adjacent
to the groove and fits into the groove.
6. The plunger of claim 2, having a plurality of circumferential
grooves in the surface of the core and a plurality of fingers on
the inner surface of each said segment, wherein the fingers of each
said segment project inwardly and cooperate to encircle said
core.
7. The plunger of claim 6, wherein the plurality of fingers and
grooves creates a tortuous path of flow for fluids and/or gases and
an increased surface area between the segments and the core which
energizes the segments and pushes the segments outwardly to cause
an outer seal with the tubulars.
8. The plunger of claim 5, wherein at least one biasing means is
placed between the inner surface of each segment and the core.
9. The plunger of claim 5, wherein at least one groove has at least
one blind hole which accommodates a biasing means, with the biasing
means disposed between the core and the segment and biasing the
segment outwardly from the core.
10. The plunger of claim 5, wherein at least one the finger has a
blind hole which accommodates a biasing means, with the biasing
means disposed between the core and the finger and biasing the
segment outwardly from the core.
11. The plunger of claim 8, wherein the biasing means is a
spring.
12. The plunger of claim 1, having a core with at least one raised
circumferential band.
13. The plunger of claim 1, having at least one furrow on the
underside of each segment.
14. The plunger of claim 12, having at least one furrow on the
underside of each segment with the band being adjacent to said
furrow and fitting into the furrow, wherein said band is separated
from said furrow unless said segments are pushed to their most
inward position.
15. The plunger of claim 14, wherein at least one band has at least
one blind hole which accommodates a biasing means, the biasing
means being disposed between the band and the furrow.
16. The plunger of claim 14, wherein at least one furrow has a
blind hole which accommodates the biasing means, the biasing means
being disposed between the band and the furrow.
17. The plunger of claim 14, having upper and lower retaining
rings, the upper retaining ring being adjacent to the top end of
the segments and the lower retaining ring being adjacent to the
bottom ends of the segments, the retaining rings limiting the
outward radial movement of the segments.
18. The plunger of claim 5, having an upper and lower retaining
ring wherein the interface between at least one finger and at least
one groove prevents detachment and loss of the segments and/or
biasing means if a retaining ring fails.
19. The plunger of claim 5, wherein the segments have first and
second sides with a tab or slot which is mutually and slidably
engageable with the corresponding tab or slot of the adjacent
segments.
20. The plunger of claim 19, wherein the tabs and slots have
stepped portions to maintain the overlapping between the tabs and
slots in all of the radial positions and to guide the segments
inwardly and outwardly.
21. The plunger of claim 19, wherein the top and bottom ends of the
segments are inwardly tapered.
22. The plunger of claim 19, wherein the segments have notched top
and bottom ends which slidably fit under the retaining rings
23. The plunger of claim 18, wherein the segments have a notch in
the outer surface of the top end and a notch in the outer surface
of the bottom end, and wherein the retaining rings have a hollow
inner surface and first and second ends, with the first end being
positioned opposite to said segments and the second end of each
retaining ring being positioned next to said segments and having at
least one downwardly projecting lug which fits into said notch in
each said segment.
24. The plunger of claim 6, wherein at least one outer top edge of
one of said grooves is angularly reduced to allow installation of
the segments underneath said retaining rings.
25. The plunger of claim 5, having a fishing piece attached to the
top end of said body.
26. The plunger of claim 5, having an end cap attached to the
bottom end of said body.
27. A plunger for use in a gas/fluid lift system in downhole
tubulars in wells producing fluids and/or gases under variable
pressures, comprising: a body slidingly engageable within the
tubulars and capable of movement up and down said tubulars; said
body having a top end and a bottom end; an inner core within the
body for internal sealing; an external sealing means having an
outside surface and an underside surface mounted about said core
radially expandable to seal against the interior of said tubulars;
a flow path for fluids and/or gases between said core and the
underside of said external sealing means; an internal sealing means
disposed between or on the core and/or the underside of said
external sealing means; said internal and external sealing means
retarding the upward flow of fluids and/or gases which thereby
increases pressure below the plunger to thereby move the plunger
and accumulated well fluids upwardly to the surface when the
pressure inside the tubulars above the plunger is reduced.
28. The plunger of claim 27, wherein the external sealing means
comprises a plurality of segments mounted around the core, the
segments having a convex outer surface and an inner surface, first
and second sides, and top and bottom ends, said segments being
slidingly and sealingly engageable with the tubulars based upon the
pressure effected between the segments and the core, and having the
largest diameter of the plunger in an expanded radial position.
29. The plunger of claim 28, wherein the segments have first and
second sides with a tab or slot, the tab or slot being mutually and
slidably engageable with the corresponding tab or slot in the sides
of the adjacent segments and assisting with the inner and outer
radial movement of the segments.
30. The plunger of claim 28, wherein the internal sealing means
comprises at least one rigid finger on the inner surface of the
segments, the finger protruding radially inward toward the core,
with the fingers of said segments cooperating to encircle the core
and being separated from the core unless the fingers are pushed to
their most inward position.
31. The plunger of claim 30, wherein the finger has a flat bottom
side and a flat top side, a curved concave inner surface, and first
and second edges which are flat and angularly aligned with the
first and second adjacent edges of the segment.
32. The plunger of claim 28, wherein the internal sealing means
comprises at least one circumferential groove in the surface of the
core.
33. The plunger of claim 30, wherein the internal sealing means
further comprises at least one circumferential groove in the
surface of the core, wherein the finger is adjacent to the groove
and fits into the groove.
34. The plunger of claim 33, wherein the elevation of the finger or
fingers is at least as great as the depth of the groove.
35. The plunger of claim 33, wherein the elevation of the finger or
fingers is less than the depth of the groove.
36. The plunger of claim 33, wherein the separation between the
grooved core and the underside of said segments and said fingers
create a tortuous path of flow and effect a turbulent inner
seal.
37. The plunger of claim 33, wherein the external sealing means
further comprises retaining means which limits the outward radial
movement of the external sealing means.
38. The plunger of claim 37, wherein the retaining means is upper
and lower retaining rings having a hollow inner surface, the upper
retaining ring being adjacent to the top end of the segments, and
the lower retaining ring being adjacent to the bottom ends of the
segments.
39. The plunger of claim 33, wherein the internal sealing means
also comprises at least one biasing means disposed between the
external sealing means and the core, and biasing the segment
outwardly from the core.
40. The plunger of claim 39, wherein at least one groove has at
least one blind hole which accommodates a biasing means, and
wherein at least one the finger has a blind hole which accommodates
the same biasing means, with the biasing means disposed between the
groove and the finger, and biasing the segment outwardly from the
core.
41. The plunger of claim 39, having an upper and lower retaining
ring wherein the interface between at least one finger and at least
one groove prevents detachment and loss of the segments and/or
biasing means if a retaining ring fails.
42. The plunger of claim 38, wherein the segments have notched top
and bottom ends which slidably fit under the retaining rings.
43. The plunger of claim 38, wherein the segments have a notch in
the outer surface of the top end and a notch in the outer surface
of the bottom end, and wherein said retaining rings have first and
second ends, with the first end being positioned opposite to said
segments and the second end being positioned next to said segments
and having at least one downwardly projecting lug which fits into
the notch in each said segments.
44. The plunger of claim 39, wherein the biasing means is a
spring.
45. A method of lifting well fluids and/or gases from a
subterranean reservoir to the surface in tubulars in wells
comprising: placing a plunger having an inner core and an external
sealing means mounted about said core radially expandable to
provide an external seal against the interior of said tubulars and
an internal sealing means disposed between or on the core and/or
beneath said external sealing means which comprises at least one
rigid finger and at least one circumferential groove disposed
between or on said core and the external sealing means inside said
tubulars to retard the upward flow of fluids and/or gases, allowing
said plunger to descend or gravitate to the bottom of the well or a
well stop, using internal sealing means to create a tortuous path
of flow between said core and said external sealing means thereby
effecting a turbulent inner seal which thereby pushes the external
sealing means outwardly to cause an external seal with the
tubulars, allowing the pressure to build up in the well to
predetermined level, opening a valve connected to the tubulars
which decreases the pressure inside the tubulars, thereby elevating
the plunger and the accumulated well fluids to the surface.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to improvements in plungers
used in a gas/fluid lift system in wells producing both fluids and
gases, such as petroleum and natural gas, under variable pressure
to facilitate the lifting of fluids from a subterranean reservoir
to the surface through a well conduit or tubulars. Plungers of this
type are designed to minimize the downward flow of fluids as well
as the upward flow of gases beneath the plunger as the plunger
travels upwardly to the surface. Tubulars include, but are not
limited to, a variety of tubes and tubular members, such as cement
casings, conduits, tubing and tubing strings which are placed in
the well conduit, and may also be referred to as the production
string. More specifically, the gas plunger invention concerns
improvements in the internal and external sealing of the apparatus.
The external sealing means or apparatus is typically comprised of a
plurality of segments, which collectively forms a jacket assembly
that sealingly and slidingly engages the well tubulars. A turbulent
inner seal is accomplished by sealing means such as circumferential
grooves on the inner core and/or fingers which project inwardly
from the segments toward the inner core which may or may not be
grooved. Alternatively, the inner surface of the segments may have
furrows and there may be raised bands on the core which also
effects a turbulent inner seal. The circumferential grooves and/or
fingers, or the bands and/or furrows, provide a tortuous path of
flow that deflects escaping gas streams and/or fluids, promotes
turbulence in the manner of a labyrinth seal, and has gas sealing
capabilities.
[0003] Another further and alternative improvement concerns a
simplified sucker rod and valve-like assembly used to regulate and
restrict the flow of fluids and gases through the internal passage
of the plunger which allows such plungers to descend to the well
bottom more rapidly than plungers without internal passages so that
flow occurs only during the downward cycle or descent of the gas
plunger.
[0004] 2. Description of the Prior Art
[0005] Differential gas pressure operated pistons, also known as
plungers, have been used in producing subterranean wells where the
natural well pressure is insufficient to produce a free flow of
gas, and especially fluids, to the well surface. A plunger lift
system typically includes tubulars placed inside the well conduit,
which extend from the reservoir(s) of the well to the surface. The
tubulars have a well valve and lubricator at the top and a tubing
stop and often a bumper spring or other type of spring assembly at
the bottom. The cylindrical plunger typically travels between the
bottom well stop and the top of the tubulars. The well is shut in
for a selected time period which allows pressures to build up, then
the well is opened for a selected period of time. When the well
valve is opened, the plunger is able to move up the tubulars,
pushing a liquid slug to the well surface. When the well valve is
later closed, the plunger, aided by gravity, falls downwardly to
the bottom of the tubulars. Typically, the open and closed times
for the well valve are managed by a programmable electronic
controller.
[0006] When the plunger is functioning properly, fluids accumulate
and stay above the plunger and pressurized gases and/or fluids
below the plunger are blocked from flowing up, around, and through
the plunger. As a result, the plunger and accumulated fluids are
pushed upwardly. The prior art devices use a variety of external,
and sometimes internal, sealing elements which allow the plungers
to block the upward flow of gases and slidingly and sealably engage
the tubulars, which accomplishes the lifting of fluids to the
surface depending upon the variable well pressures. Examples of
prior art gas operated plungers include those disclosed in U.S.
Pat. Nos. 5,427,504 and 6,045,335 (hereinafter the '504 and '335
patents). The prior art plunger of the '504 patent features
mechanical sealing which is accomplished by segments that are
biased outwardly against the tubulars by springs. The build up of
internal pressure is accomplished by a flexible, elastomeric seal
placed beneath the segments. The outer sealing assembly is
comprised of a plurality of segments or pads. However because such
resilient compounds like rubber do not last for extended periods of
time in the harsh well environment, problems with inner sealing
develop and the plunger must be taken out of service for
time-consuming seal replacements. Further, if the inner spring
member which assists in biasing of the segments becomes detached or
lost, sealing problems could result.
[0007] In contrast, the prior art plunger of the '335 patent has
upper and lower sets of segments whose sides are juxtaposed with
respect to each other and collectively work together. The segments
are biased outwardly against the tubulars by springs and the build
up of internal pressure. The sealing element therein consists of a
rigid inner ring member surrounding the intermediate portion of the
piston body, which is positioned between the piston body and
between the inner surfaces of each set of cylindrical segments,
which cooperate to slidingly engage the rigid ring member and
create an inner seal. However, the segments of this design can be
prone to leakage.
[0008] Other prior art plungers which have externally grooved
surfaces and which lack outer sealing elements or segments are, for
example, disclosed in U.S. Pat. Nos. 4,410,300 and 6,200,103. These
external grooves deflect the escaping gas streams and promote
turbulence in the manner of a labyrinth seal and have gas sealing
capability. However, the grooves are prone to structural failure
due to external wear and erosion due to contact with the tubulars,
and these plungers can also become jammed within the tubulars
because these types of plungers do not have the capability of
contracting radially inward, as do the plungers with cooperating
mechanical sealing segments. The improved plunger design
incorporates the concept of a labyrinth seal in its internal
sealing elements.
[0009] Other examples of prior art gas operated plungers include
those with internal bores or passages to speed the descent of the
plungers. These plungers have a variety of valve closure members
which seal the internal bore, and the prior art valve closure
members are often spring loaded and work in conjunction with long
rods which typically extend downwardly through the bore to unseat
the valve closure member, as disclosed in the '504 and '335
patents. The design of the piston disclosed in the U.S. Pat. No.
6,045,335 includes a complicated valve mechanism which requires a
unit to capture the piston at the surface and requires a long rod
which moves downwardly through the plunger bore to disengage and
unseat the valve closure member, and to open the internal valve.
However, this rod used to reopen the valve assembly is prone to
damage and bending if the rod and plunger bore become even
partially unaligned, requiring expensive and time-consuming repair
or replacement. Additionally, this type of plunger also requires
expensive and customized installation of equipment at the well
surface such as spring loaded stops to accomplish disengagement of
the valve closure member. In contrast, the plunger of the '504
patent has a bypass valve with a ball-shaped closure member and a
spring loaded rod activator, or shock spring, which pushes the ball
up into the valve seat to seal off the flow path. The spring loaded
rod activator opens the valve after the plunger reaches the
lubricator at the top of the well and the pressures above and below
the plunger are equalized.
[0010] In contrast, the improved stopper assembly which is housed
in a chamber is typically located in a modified end cap and seals
off the inner flow passage in a simplified manner. The stopper stem
and stopper head is pushed up into the chamber when the plunger
bottom contacts the well stop means, and the stopper is held up
against the opening of the flow passage by the fluid and/or gas
pressure below the plunger. This simplified and improved design
dispenses with the need for complicated moving parts which to
actuate the closure means, and eliminates the need for expensive
equipment at the well head which is used to unseat the closure
means.
[0011] The improved plunger inventions seek to dispense with the
problems of the prior art such as erosion, leakage, erratic or
unsafe operation, malfunctions, and costly replacements or repairs.
Many other objects and advantages of the inventions, besides
substantially trouble free operation, will be apparent from reading
the description which follows in conjunction with the accompanying
drawings.
SUMMARY OF THE PRESENT INVENTION
[0012] The present invention provides a plunger for use in a
gas/fluid lift system in tubulars in wells producing both fluids
and gases under variable pressure. The plunger assists with the
build up of pressure between the subterranean reservoir and the
surface by having an inner seal and an external sliding and
variable holding seal with adjacent well tubulars. The inner and
external seals restrict the upward flow of the fluids and/or gases.
This causes an increase in the well pressure below the plunger and
facilitates the upward lifting of the plunger and fluids from the
reservoir to the surface when pressure is reduced above the
plunger, such as at the well head, The improved plunger comprises a
body which is slidingly engageable and which gravitates within the
tubulars. The plunger body has an external sealing means such as a
plurality of segments which are mounted around a core, also known
as a mandrel, and which collectively form a jacket. The segments,
collectively the jacket assembly, are slidingly and sealingly
engageable with the insides of the well tubulars, based upon the
pressure effected between the inner surface, or inside, of the
jacket and the core. The jacket has the largest diameter of the
plunger when the segments are in an expanded radial position. The
segments have a convex outer surface and typically have a concave
inner surface. However, the core of the plunger could be square,
triangular, or of another geometric shape, in which case the inner
surfaces of the segments could be flat, or of any other
corresponding geometric shape.
[0013] In a preferred embodiment of the plunger, there is also an
inner sealing means such as at least one rigid finger which
projects radially inward from the underside of each segment toward
the core, with the fingers of the adjacent segments collectively
cooperating to encircle the core. Preferably, there are a plurality
of fingers on the undersides of each segment. The fingers are
normally separated from the core especially when the segments,
collectively the jacket, are pushed radially outward. This creates
a path of flow for gases and/or liquids and the fingers
collectively create a tortuous path of flow between the core and
the segment undersides and effect a turbulent inner seal. When the
segments making up the jacket are pushed to their most radially
inward position, the fingers touch the core and cause a complete
inner seal. In another embodiment of the plunger, the core has at
least one circumferential groove on its surface, and more
preferably a plurality of grooves. This also creates a tortuous
path of flow between the core and the jacket underside and effects
an inner seal. In another embodiment, the plunger has both grooves
and fingers, and the fingers are correspondingly located to fit
into the grooved portions of the core. This design creates an even
more tortuous path of flow for fluids and gases which effects an
inner seal and creates an increased surface area between the
segments and core. The increased surface area also has the effect
of increasing the internal plunger pressure, i.e., the pressure
between the core and the jacket assembly and energizes the
segments, pushing the segments radially outward toward the well
tubulars. This preferred design also prevents detachment and/or
loss of the segments if the retainer rings, explained below, fail
because the segments will be held in place by the finger-groove
interface and by the outer well tubulars. This design provides for
increased functionality and seeks to minimize expensive and time
consuming fishing operations to retrieve dislocated parts.
[0014] An alternate embodiment also has at least one biasing means,
which is typically a spring, between the underside of each segment
and the core to outwardly bias each segment and to achieve inward
and outward radial rebounding of the segments from the inner core.
The preferred embodiment also has recessed spaces, or blind holes,
in the core or core grooves and/or the fingers which hold the
biasing means in place between the core and segments and prevent
displacement and loss of the biasing means. The preferred
embodiment typically also has retaining means such as retaining
rings which limit the outward radial movement of the
segments/jacket assembly. In plungers with both fingers and
grooves, at least one of the outside edges of the grooves will be
angularly reduced to allow installation of segments with projecting
fingers into the grooves of the core and allows the end of the
segments to be installed underneath the retaining rings.
[0015] In yet another embodiment of the invention, the plunger has
an internal passage which extends partway through the body, or
through the entire axis of the plunger, to facilitate more rapid
descent of the plunger to the bottom of the well or the well stop
means. These plungers also have a top end and a bottom end with at
least one opening at or near the top and the bottom end and may
have a plurality of radial ports which connect to the bore to
increase the flow rate and to facilitate even more rapid descent of
the plunger. The preferred embodiment has a plurality of radial
ports near the top end and bottom end. These plungers further have
a chamber in a modified end cap near the bottom end which houses a
closure means such as a plunger stopper. The chamber connects to
the internal passage at the roof and connects to the stem bore in
the floor of the chamber. The plunger stopper has a top end which
has a shape similar to that of the roof, or upper chamber area, and
has a stem attached to the bottom end which extends downward
through and protrudes outwardly from a bore opening in the bottom
end. When the stem engages the bottom well stop means upon descent,
the closure means such as a stopper, is pushed upwardly against the
roof of the chamber, thereby sealing off the inner flow passage and
restricting the upward flow of fluids and/or gases in order to
build up pressure below the plunger. The improved design of this
closure means, or stopper, operates without springs or catches, yet
still holds the stopper against the roof of the chamber. It also
does not use long sucker rod, which are prone to bending, to unseat
the closure means. Instead, the pressure build-up below the plunger
keeps the plunger stopper engaged against the roof of the chamber.
The simplified bore sealing means also reduces the amount of time
needed for costly and time-consuming repairs and replacements and
dispenses with the need for expensive and customized devices at the
surface that unseat the prior art closure valves.
[0016] The preferred embodiments of this invention may also have
the previously described advantages of the rigid fingers, the
grooved core, the spring recesses, and the reduced edge of the core
groove. In another preferred embodiment of the invention, the top
end of the closure means, such as the plunger stopper, also has a
stem which is pushed upward into the inner passage above the
chamber roof to further seal off the inner passage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Details of this invention are described in connection with
the accompanying drawings that bear similar reference numerals in
which:
[0018] FIG. 1 is a schematic representation of an operating well
and production of the well by utilizing a gas operated plunger
according to an embodiment of the invention;
[0019] FIG. 2 is a longitudinal, external view, of a gas operated
plunger;
[0020] FIG. 3 is an upper end view of the four segments of the
embodiment of FIG. 2;
[0021] FIG. 4 is an inner, perspective view of the grooved core and
jacket assembly of the segments of FIGS. 2-3, with one of the
segments removed;
[0022] FIG. 5 is a longitudinal view of two of the four cooperating
segments which form the jacket assembly for use with the preferred
embodiment of FIG. 18;
[0023] FIG. 6 is a view of the upper end of the four segments of
FIG. 5;
[0024] FIG. 7 is an inner, perspective view of one of the segments
of FIGS. 5-6;
[0025] FIG. 8 is an outer perspective view of one of the segments
of FIGS. 5-6;
[0026] FIG. 9 is an inner planar, or flattened, perspective view of
one of the segments of FIGS. 5-7;
[0027] FIG. 10 is an outer planar, or flattened, perspective view
of one of the segments of FIGS. 5-6, 8;
[0028] FIG. 11 is a cross-sectional view of the segments of FIGS.
6, 9, taken across lines D-D of FIG. 9;
[0029] FIG. 12 is a cross-sectional view of the segments of FIGS.
6, 9, taken across lines A-A of FIG. 9;
[0030] FIG. 13 is a cross-sectional view of the segments of FIGS.
8, 10, taken across lines C-C of FIG. 10;
[0031] FIG. 14 is a cross-sectional view of the four segments of
FIGS. 5, 6, taken across lines B-B of FIG. 10;
[0032] FIG. 15 is a cross-sectional view of the segments of FIGS.
8, 10, taken across lines B-B of FIG. 10;
[0033] FIG. 16 is a detailed drawing, partially in section,
illustrating the biasing means of the preferred embodiment of FIG.
18, and the sectional view of the grooves and segments of FIGS. 9,
12;
[0034] FIG. 17 is a detailed drawing, partially in section,
illustrating the flow in the area between the segments and grooves
in FIG. 16 of the preferred embodiment of FIG. 18;
[0035] FIG. 18 is a longitudinal view, in quarter section, of a
preferred embodiment of a gas operated plunger;
[0036] FIG. 19 is an outer perspective view of the installation of
one of the segments underneath a retaining ring;
[0037] FIG. 20 is a longitudinal view, in quarter section, of a gas
operated plunger which has a chamber and an internal passage and
valve closure means in the open position;
[0038] FIG. 21 is the top view of the fishing piece of the plunger
of FIG. 20;
[0039] FIG. 22 is the bottom view of the plunger of FIG. 24;
[0040] FIG. 23 is a sectional view of the chamber of the plunger of
FIG. 20 with the closure means in the closed position;
[0041] FIG. 24 is a sectional view of the chamber of an alternate
embodiment of a plunger and a plunger stopper in the open position;
and
[0042] FIG. 25 is a sectional view of the chamber of an alternate
embodiment of a plunger and a plunger stopper in the open
position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] Referring first to FIG. 1, there is shown a producing well W
for producing hydrocarbon fluids from a subterranean reservoir R.
The well maybe of the horizontal or vertical variety. The plunger
pump P is preferably used in wells where the gas pressure alone is
insufficient to produce the flow of liquids or the significant flow
of fluids at the surface. In these situations, hydrocarbons from
such wells cannot be recovered except through the installation of
considerably expensive submersible pump units which require daily
inspection and maintenance. Similarly, in wells producing primarily
gas, the gas production may be substantially impaired by fluids,
whether hydrocarbons or salt water, which accumulate in the bottom
of the well. In either event, it is desirable to remove fluids from
the bottom of such wells without installing conventional pumping
units. Typically, one or more well conduits extend from the
subterranean reservoir R to the well surface WS. In the preferred
embodiment, there is a casing string CS, at the upper end of which
is a well head WH, and a tubular string T, also known as
"tubulars." Tubulars T is a generic term used to define the variety
of tubes and tubular members, such as cement casings, conduits, and
tubing and tubing string, which can also be referred to as the
production string, which can be made from a variety of materials
such as plastic, metal, and concrete. Tubulars line the well
surface and can also be placed inside or on the outside of other
tubulars. In any event, the tubulars are the well channels through
which fluids from the subterranean reservoir R are raised to the
surface. Near the bottom of the tubulars is a tubing stop means TS
mounted in any suitable manner. The tubing stop means or mechanism
TS may be relocated by wire line or other operations at different
depths as well conditions change. The tubing stop TS preferably
incorporates a bumper spring B of some type for stopping downward
movement of a plunger type pump unit P, which is slidably and
sealably disposed in the tubulars T and which will be described in
greater detail hereafter. At the well surface WS is a master cutoff
or motor operated valve V suitably attached to the tubing string T
to entirely block the flow of fluids from the tubulars T as
desired. This arrangement further allows retrieval of the plunger
pump P for inspection or repair. Above the valve V is a flow tee F
and a lubricator L closed at its upper end by detachable end cap E.
A bumper sub BS is usually placed therein with a spring (not shown)
which is engageable by the plunger pump P when rising through the
tubulars TS to stop movement of the plunger P and to cushion the
shock created thereby. Connected to the flow tee F is a production
or pay line PL in which is installed a motor control valve MV. An
electronic controller EC is provided for operating the control
motor valve MV. The electronic controller EC is also connected to a
tubing plunger sensor S for sensing the pressure within the
wellhead WH. A plunger catching device PC may also be attached to
the tubing string T above valve V.
[0044] Initially, the plunger P is placed in the tubulars through
the lubricator sub L. This is done by removing the cap E while the
valve V is closed. Then the cap E is replaced, the valve V opened,
and the plunger P is allowed to gravitate or fall to the bottom of
the well through the tubulars T. Although the sealing means, such
as a jacket 100 made of segments, e.g., 46, 47, 48, 49, is biased
outwardly for sliding and sealing engagement with the interior of
the tubulars T, there is a small amount of leakage around the
outside of the jacket assembly 100 and through the edges of the
sealing segments 46, 47, 48, 49. This permits the plunger P to fall
under its own weight toward the tubing stop TS which will arrest
its downward movement. When this occurs, the cutoff valve V is
closed and a time sequence is initiated by the controller EC.
Additional fluids enter the tubulars T and the gas and/or fluid
pressure begins to build. The controller EC is programmed to keep
the valve V closed until substantial fluids have entered the
tubulars T and sufficient gas pressure has built up within the
well. The amount of time necessary will be different for every well
and may change over the life of the well. After a predetermined
amount of time, the controller EC opens the valve V, which
substantially reduces the pressure above the plunger P.
Consequently, the accumulated gas pressure therebelow forces the
plunger P, and the fluids trapped thereabove, upwardly through the
conduit or tubulars T, through the flow tee F, the valve V and the
pay line PL for production of the well. As the plunger P is
propelled upwardly through the tubulars T by pressure, it passes
through the valve V, and is sensed by the sensor S and eventually
movement thereof is arrested by a spring (not shown) in the
lubricator sub L. When the plunger P is detected by the sensor S, a
signal is transmitted to the controller EC which initiates closure
of the valve V. Thereafter the plunger P is allowed to again
gravitate or fall to the bottom of the well so that this cycle can
be repeated.
[0045] In describing the specific embodiments herein which were
chosen to illustrate the invention, certain terminology is used
which will be recognized as employed for convenience and having no
limiting significance. For example, the terms "upper," "lower,"
"top," "middle," "bottom," and "side" refer to the illustrated
embodiment in its normal position of use. The terms "outward" and
"inward" will refer to radial directions with reference to the
central axis of the device. Furthermore, all of the terminology
defined herein includes derivatives of the word specifically
mentioned and words of similar import.
[0046] Referring now also to FIGS. 2-25, the drawings show a
plunger pump which is used in a gas/fluid lift system in the
tubulars T of wells which produce both fluids and gases under
variable pressure. Referring now to the drawings in detail, FIGS.
1, 2, 18, and 20 show a plunger which has a body that is slidingly
engageable within the well tubulars T. The body is typically made
of rigid material, such as any type of metal or metal alloys, rigid
plastics and polymers, ceramics, and the like, with the preferred
embodiment being made of stainless steel. The body also has an
inner core 10, for support and for inner sealing. The core 10 may
also be known as a mandrel, and may be solid or hollow. The core is
typically substantially cylindrical and typically has the smallest
diameter of the plunger body.
[0047] As in FIG. 2, there is a flexible jacket assembly 100
surrounding or mounted about the core 10. The preferred embodiment
has four segments 20, 21, 22, and 23, which collectively form a
flexible jacket assembly 100. These segments 20, 21, 22, and 23,
are made of a relatively rigid material, such as those known in the
art, like metal, hard rubber, plastic, graphite, etc., and
typically have a relatively smooth outer surface, due to the die
cast molding of the segments, and/or polishing of the segments, for
sliding and sealing contact with the walls of the well tubulars in
which the plunger P is to be used, such as the inner walls of the
tubulars T in FIG. 1. Referring now to FIGS. 2, 3 and 4, each
segment typically has a substantially convex outer shape 30 and a
substantially concave inner surface 32, like that of a semicircular
arch. Each segment 20-24, or 46-49 (see FIGS. 5-8) has
substantially the same width and curve so that several segments can
be placed side by side to form a flexible jacket assembly 100,
which is mounted around the core 10, such as by upper and lower
retaining rings 150 and 160, respectively. The retaining rings 150,
160, which limit the outward radial movement of the jacket
assembly. The inner surface of the jacket assembly 100 is separated
from the core 10, unless it is pushed to its most inward
position.
[0048] The sealing segments 20, 21, 22, 23, which collectively
makeup the jacket assembly 100, are typically held in position
around the core 10 of the plunger body by retaining means such as
an upper retaining ring 150 and a lower retaining ring 160, which
slip on over the core 10, with the upper retaining ring usually
abutting the collar 421 of a fishing part 420. As in FIG. 19, the
top end 400 of the core 10 is also typically substantially
cylindrical and has means such as threading, i.e., a helical or
spiral ridge which can be used to removably or securably attach, by
screwing, into or onto another part. Alternatively, drilled or
threaded holes in both the plunger body and the other part can also
be used to securably attach the other parts to the plunger, or they
may be connected by threads, welding, soldering, pins, screws or a
combination thereof. Other parts includes plunger parts, plunger
accessories, or other oil field components or tools.
[0049] The preferred embodiment has a threaded upper end fishing
piece 420 which is typically threadingly connected to a threading
430 near the top end of the core 400 and has a head 425 located
above a fishing neck 424 of a reduced diameter that is removably
attached to the top end 400 and may also be secured with a set
screw, e.g., 415. The fishing piece 420 may also have a wrench flat
423, to assist in loosening or tightening. Alternatively, the
fishing piece or part 420 may be tooled into the core 10. The lower
retaining ring usually abuts an end cap 140. The bottom end 425 of
the core 10 typically has means such as threading 435 to attach
other parts. In the embodiment of FIG. 18, a plug or end piece 140
is threadedly connected to corresponding threads 435 on the lower
end of the core 10, and may have a tapered end 142. The cap may be
provided with wrench flats 142 for aiding in the engagement or
disengagement of the threaded connection and a set screw (not
shown) may be tightened when the cap is fully engaged as to prevent
accidental loosening or disengagement. Alternatively, the end cap
140 may be tooled into the bottom end 425 of the core 10.
[0050] The upper and lower ends of each of the segments may also
have notches across the ends as in 21c, 23c, or recessed ends such
as in 21d, 23d, which cooperate to fit under the retaining rings
150, 160. This limits the movement of the jacket assembly 100
radially inwardly and outwardly from the core 10. The upper and
lower ends of the segments may also be inwardly tapered as in 20a,
21a, 22a, 23a, so that when the segments engage a restriction in
the well tubulars T, the segments will be forced toward their most
inward position. This allows the plunger to overcome the
restriction and to pass through the restricted area. In their
innermost position 290, the segments, e.g., 21-24 and 46-49, have a
diameter less than that of any restriction to be encountered in the
tubulars. Referring now to FIGS. 1 and 2, the jacket assembly also
has the largest diameter 300 of the plunger when the jacket
assembly 100 is in its most radially expanded position 300, when it
sealingly engages the tubulars. Referring now to FIGS. 1, 3, and 4,
the jacket assembly 100 is also slidingly and sealingly engageable
within the well tubulars T, based upon the pressure effected by the
flow path 200 between the underside of the jacket 100 and the core
10 by the gas and fluids that move upwardly between the segments
20, 21, 22, and 23, and based upon the outward biasing force of the
jacket assembly against the tubulars T.
[0051] Typically, the segments are substantially rectangular 25.
However, the segments 20, 21, 22, 23, and 46, 47, 48, 49, may be a
variety of geometric shapes, sizes, and dimensions, as long as they
are able to cooperate to surround the core or to form a jacket
assembly 100. One such variation of segments 46, 47, 48, 49 of the
preferred embodiment are shown in FIGS. 5, 7-15, 18, and 20. One of
the segments 48 is in inner and outer perspective views in FIGS. 5,
7, 8, 9, and 10, and cross-section in FIGS. 11, 12, 13, and 15.
FIG. 6 is an upper end view of the segments 46-49. FIG. 14 is a
sectional view of the segments 46-49 at section B-B, in their most
inward position. Each of these segments 46, 47, 48, 49, is provided
with a convex, or substantially convex outer surface, 51, 52, 53,
54, respectively. The inner surfaces of the segments are
substantially cylindrical in shape, e.g., 61, 62, 63, and 64. The
segments of the preferred embodiment further have sides which have
a tab 60 or slotted 61, 67 portion, preferably with a tab 60 on one
side and a slot 61, 67 on the opposing side, as in FIGS. 5, 7, and
8. For example in FIG. 5, segment 48 has a tab 60 which is engaged
with slot 61 of segment 49. See also segments 46 and 47 in FIG. 14,
with tabs 64, 66, respectively and slots 63, 65, respectively. The
cross-section of segments 60, 62, 64, 66, as in FIG. 14, show that
when the mutually engageable tabs 46, 47, 48, 49 are interconnected
with the slots 61, 63, 65, 67 located on the sides of the adjacent
segments, that a circumferential jacket assembly 100 is formed. In
FIGS. 6, 8, and 9, these tabs, e.g., 60, and slots, e.g., 67, have
stepped areas so that a portion of a tab 60a overlaps an inset
portion of a corresponding slot 67a, 67b. The overlapping is
accomplished with opposing surfaces, e.g., 67a and 60a, which are
slidably engageable with the opposing surfaces of the adjacent
segments 46-49, and which guide the segments inwardly and outwardly
between their innermost and outermost radial positions. These
overlapping, opposing, sealing surfaces are planar surfaces which
are tangentially disposed relative to a cylinder whose axis
corresponds with the axis of the core 100 of the plunger body about
which the segments are disposed. The overlapping surfaces further
minimize leakage from the flow path 200 of FIGS. 16, 17, between
the core and the segments, and therefore assist in inner
sealing.
[0052] The upper and lower ends of these segments may also be
inwardly tapered as at 51a, 52a, 53a, 54a, and 51b, 52b, 53b, 54b,
respectively, so that when the segments engage a restriction in the
well tubulars, the segments will be forced inwardly to allow the
plunger to pass through the restriction. In the preferred
embodiment, the upper ends of each segment have a semicircular
notch 70, 72, 74, 76, as do the lower ends of such segments 71, 73,
75, 77, which slidably fit under the lugs, e.g., 153, 163, 164 of
the retaining rings. See FIGS. 18, 19.
[0053] The preferred embodiment further has segments wherein the
inner surface or underside, e.g., FIGS. 7, 16, possess at least one
finger 120 which is preferably made of rigid material, such as
metal, plastic, hard rubber, graphite, and the like. The rigid
fingers 120 of the exemplary embodiment are made of metal and are
an integral part of the segment 46, 47, 48, 49 which is molded. The
exemplary embodiment has three fingers 120 on the underside of each
segment 61, 62, 63, 64, respectively. See, for example, FIG. 6.
Preferably, there is a plurality of rigid fingers on each segment
underside, with the preferred embodiment, e.g., FIGS. 4, 7, 19,
having three such fingers 120 on the underside of each segment 32,
63, respectively. The fingers 120 of each segment protrude radially
inward toward the core 10 and are parallel and horizontally aligned
with the fingers 120 of the adjacent segments to collectively
cooperate to encircle the core 10, and serve as part of the
internal sealing means. The fingers 120 and one 10 are typically
separated by space, or a flow path 200 unless the fingers are
pushed to their most inward position. If the core 10 also has
grooves, e.g., 12, 14, 16, the fingers 120 on the underside of the
segments 46, 47, 48, 49 are adjacent to and aligned with the
grooves 12, 14, 16, and the fingers 120 fit into the grooves, 12,
14, 16. See FIGS. 3, 19. Where both fingers and grooves are
present, there is an increased surface area between the inner
surface of the segments and the core which energizes the segments
and pushes the segments outwardly to cause an external seal with
the tubulars. Typically during operation, the fingers 120 and core
10 or core grooves 12, 14, 16, are separated by a space, or flow
path 200.
[0054] As in FIGS. 3, 7, 13, each finger 120 is defined by top 120f
and bottom side surfaces 120b. The fingers 120 may be in a variety
of geometric shapes. For example, the fingers 120 may have a
cross-section such as that of a V-shape, wherein the top and bottom
sides converge (not shown), or conversely the side surfaces may
diverge with respect to one another (not shown). In the preferred
embodiment, the fingers 120 also have an inner surface 120d which
is a curved concave shape, which is complimentary to the shape of
the core 10. However, the inner surface of the finger 120 could
also be semicircular in cross-section, with a convex inner surface
(not shown). Many other variations and combinations thereof are
also possible. Further, the finger has first 125a and second side
edges 125b which are flat and angularly aligned with the first and
second adjacent side edges of the segment, e.g., 48a, 48b,
respectively. The elevation of the fingers 120 may vary. In the
embodiment having a grooved core 12, 14, 16, the elevation of the
fingers 120 may be at least as great as the depth, e.g., 18b of the
groove, e.g., 12, 14, 16, 18, or conversely, less than the depth of
the groove 12, 14, 16. However, the fingers 120 must be of a
narrower width than that of the corresponding groove, so the
fingers 120 can fit into such grooves, e.g., 12, 14, 16. See FIGS.
18, 19. Further, the fingers 120 may be of a uniform or variable
elevation, shape, and width with respect to one another.
[0055] Now referring back to the fingers on the underside of the
segments, in the preferred embodiment, the top and bottom side
surfaces 120f, 120b of the finger 120 has an angle of substantially
90 degrees, relative to the outer surface of the core 11, and has
an inner surface 120d which is substantially parallel to the outer
surface of the core 10. The finger 120 of this design has a square
or rectangular cross-section. See, e.g., FIGS. 5, 18, 20.
[0056] Alternatively, the fingers may be located on the surface of
the core 11, and would be referred to as "bands" (not shown). The
core may have one circumferential band, or a plurality of
circumferential bands. In this case, the bands have corresponding
elements and features equivalent to those found in the fingers. The
bands may be found in an embodiment with or without corresponding
furrows on the underside of the segments (not shown). In this case,
the furrows have corresponding elements and features equivalent to
those found in the grooves of the core. The underside of the
segments may have one furrow, or a plurality of furrows which
collectively form a circumferential furrow. When there are both
bands and furrows present (not shown), the bands on the surface of
the core 11 (not shown) fit into the corresponding furrows on the
underside of the segments (not shown). The bands maybe a variety of
shapes and widths, similar to those described for the fingers.
Preferably, the band has a flat bottom side and a flat top side and
a curved outer surface. The bands may also have a variety of
elevations, and may be at least as great or less than the depth of
the furrow (not shown). Similar to the plurality of fingers and
grooves, a plurality of bands and/or furrows create a tortuous path
of flow for fluids and gases and an increased surface area between
the undersides of the segments and the core which would energize
the segments and push the segments outwardly to cause an outer seal
with the tubulars. Further, a plurality of bands and/or furrows
also provides a tortuous path of flow and effects an inner
turbulent seal and retards the upward flow of fluids and gases and
causing an increase in pressure below the plunger. Similar to the
fingers and grooves, the biasing means may be placed between the
core and the segments. Also similarly, there may be at least one
blind hole in each band which accommodates a biasing means,
discussed below, under each segment. The biasing means may also be
disposed between the band and the furrow (not shown). Further, at
least one furrow in each segment may have a blind hole which
accommodates the biasing means with the biasing means being
disposed between the band and the furrow (not shown).
[0057] The core 10 of the plunger body in FIGS. 16, 17, 18 may also
possess internal sealing means such as one grove or a plurality of
longitudinally spaced circumferential grooves 12, 14, 16, 18 which
are defined by recessed surfaces that are interspersed between the
ungrooved sections of the surface of the core 11. There is also an
inner turbulent sealing effect, FIG. 4, when the embodiment has an
ungrooved core and at least one, or preferably a plurality of
fingers, e.g., 120 which project inwardly toward the core 11. There
is an even more dramatic inner sealing effect where the embodiment
has grooves 12, 14, 16 as well as projections, e.g., 120.
[0058] Each groove, e.g., 12, 16 is defined by a recessed surface,
e.g., 12b, 18b and upper and lower side surfaces, e.g., 18a and
18c, respectively. In the preferred embodiment, the lower surface
portion 12b, 18b has an angle of substantially 90 degrees, relative
to the outer surface of the core 11, and have upper and lower
portions 12a, 12c, and 18a, 18c, that have an angle of
substantially 90 degrees, relative to the outer surface of the
ungrooved core 11a. The core of this design has a square or
rectangular cross-section, see, e.g., FIG. 16. The preferred
embodiment of the plunger has a core 10 which includes a plurality,
preferably three, of longitudinally spaced circumferential grooves,
e.g., 12, 14, 16, that divide the peripheral surface of the core 11
into a plurality of outer surface sections, e.g., 11a, 11a. Again,
due to the necessity for clearance between the plunger P and the
tubulars T which allows the plunger to fall or gravitate to the
bottom of the well, a flow passage is formed between the jacket and
the tubulars, and some of the gas below the plunger P will flow up
between the plunger P and the tubulars T, as well as up into the
plunger beneath the jacket assembly and the core. As shown in FIGS.
16, 17 the gas also enters into the flow path 200 between the
segment 48 and the core surface 11, 11a, a first portion F.sub.1 of
the gas flows along the surface of the ungrooved core 11a and the
segment underside 63, and a second portion F.sub.2 flows down into
the groove, e.g., 16, 18 and recessed surface, e.g., 18b. The four
right angles at each corner, 13a, 13b, 13c, 13d, and along the
recessed surface 18b and the top 18a and bottom sides 18c of the
groove 18 cause the first portion F.sub.1 and second portion
F.sub.2 of flowing gas meet at substantially a right angle at the
corner 13a, creating a turbulent flow region T.sub.1, that inhibits
liquid flow downward into the groove and inhibits gas flow upward
out of the groove. The gas flowing up along the plunger core
surface 11, 11a dissipates energy at each successive groove, e.g.,
16, 14, 12. Alternatively, the grooves may be located in the
underside surfaces of the segments, e.g., 46-49 (not shown). In
that situation, the grooves would have corresponding elements and
features equivalent to those found in the grooves, e.g., 12, 14,
16.
[0059] The groove may also be in the form of a spiral, or
conversely in a variety of geometric shapes, and, for example, may
have a cross-section such as that of a V-shape, or top and bottom
sides that converge or diverge with respect to one another, or a
semicircular cross-section (not shown). Many other variations are
also possible. For example, the depth and/or length of the
recesses, e.g., 18b, may be variable, as well as the length of the
body sections 11a between the recesses. Further, the grooves, e.g.,
12, 14, may be of a uniform or variable depth, shape, and width,
with respect to one another.
[0060] As best seen in FIGS. 16, 18, the preferred embodiment may
also have biasing means, which are typically springs 190, disposed
between the core 10 and the underside or inner surface of the
segment, e.g., 61, 62, 63, 64 which biases the segments, e.g., 46,
47, 48, 49, outwardly from the core 10. The biasing means may take
the form of a helically wound spring 190 or leaf spring or other
member which has the ability to rebound or recoil after being
compressed. Further, the core 10 may possess a blind hole 180, or a
blind hole 182 may be present in the core groove 185, e.g., 12, 14,
16. Preferably there are two biasing means, e.g., 190 between each
segment, e.g., 46, 47, 48, 49 and the adjacent area of the core 10
or core groove, e.g., 12, 14, 16. The biasing means 190 are
preferably placed about midway across the width of the segment and
at places along the length of the underside that leave the segment
balanced against the core 10. The blind holes, e.g., 180, 182,
accommodate and hold the biasing means, e.g., 190 in place. The
finger of the preferred embodiment may also have a blind hole 185
which accommodates a biasing means, e.g., 190. Preferably the
embodiment has a blind hole in both the core 180 or core groove 182
and the underside of the adjacent segment 185 (not shown) or finger
120. This design minimizes the risk of loss of the biasing means
190.
[0061] Referring to FIG. 1, the gas below the plunger P must have
sufficient pressure to overcome the weight of the plunger P and a
liquid slug LS on top of the plunger P, and the pay line PL
pressure, in order to move the plunger P up the tubulars T. Due to
the necessity for clearance between the plunger P and the tubulars
T which allows the plunger to fall or gravitate to the bottom of
the well, a flow passage is formed between the jacket 100 and the
tubulars T, and some of the gas below the plunger P will flow up
between the plunger P and the tubulars T, as well as up into the
plunger beneath the jacket assembly 100 and the core 10. As shown
in FIGS. 16, 17 once the gas and/or fluids enter into the flow path
200 between the segment 48 and the core surface 11, 11a, a first
portion F.sub.1 of the gas flows along the surface of the core 11
and the segment underside 63, and a second portion F.sub.2 flows
down and around the raised finger 120. The four right angles at
each corner of the finger, 120a, 120c, 120e, 120g, and along the
surfaces of the bottom 120b and top sides 120f and inner surface of
the groove 120d, cause the first portion F.sub.1 and second portion
F.sub.2 of flowing gas to meet at substantially a right angle at
the corner 120e, creating a turbulent flow that inhibits liquid
flow downward into the areas of the segment between the fingers
which have lower elevations and inhibits gas flow upward out of the
segment area between the fingers. The gas flowing up along the
plunger core surface 11, 11a dissipates energy at each successive
finger, e.g., 120. There is an even more dramatic inner sealing
effect where the embodiment has some grooves 12, 14, 16 in the core
10, as well as projections, e.g., 120, FIGS. 16, 18.
[0062] The sealing segments 46-49 are mounted around the core 100
of the plunger body and are preferably held in place by a retaining
means such as an upper retaining ring 150 and a lower retaining
ring 160. See FIGS. 2, 4, 18, 19. The retaining rings 150, 160 are
substantially cylindrical and have a hollow inner surface of
slightly larger diameter than the core 10 and a shape which
corresponds to the shape of the core 10. The retaining rings also
have first 151, 161 and second 152, 162 ends, with the first ends
151, 161 having a plurality of lugs positioned next to the
segments, and the seconds ends being positioned on the opposite
side of the segment ends. Preferably the retaining rings 150, 160
have a plurality of lugs, e.g., 163, 164, preferably four, which
are spaced at ninety degree intervals around the retaining rings
150, 160, and which are positioned to protrude inwardly toward the
segments and are oriented to engage the notches 70, 72, 74, 76 at
the upper ends of the segments 46, 47, 48, 49, as in FIGS. 5, 6,
and the lower ends of the segments, e.g., 71, 73. The retaining
rings 150, 160 may also serve to hold the fingers 120 in position
over the grooves, e.g., 12, 14, 16, 18, in the core 10. The upper
retaining ring 150 is slipped over the core 100 of the plunger body
and is positioned adjacent to the segments, 46-49, and may also be
adjacent to the shoulder 410 of the fishing piece 420, which may be
tooled into the top end of the core 10, or removably attached to
the body such as by threading 430. The retaining 150, 160 rings may
be held in place by a set screw 415, which is screwed into a
drilled hole 420 in the core 10. See FIGS. 18, 19. Similarly, the
lower retaining ring 160 is slipped over the core 100 of the
plunger body and is positioned adjacent to the segments, 46-49, and
may also be adjacent to the end cap 220, which may be tooled into
the bottom end of the core 10, or removably attached to the body
such as by threading 225, and may also have corresponding lugs.
Alternatively, the segments, e.g., 21, 23, 48 may have a slotted,
e.g., 21c, 23c or notched top, e.g., 70 and bottom ends, e.g., 71
which slidably fit under the retaining rings, and limit the outward
radial movement of the segments, e.g., 21, 23, 48.
[0063] Further, in an embodiment having a grooved core, e.g., 12,
14, 16 and fingers 120, and upper 150 and lower retaining rings
160, the bottom edge of the uppermost groove, e.g., 16 of the core
10 is angularly reduced to allow installation of the segments 46,
47, 48, 49 underneath the upper retaining ring 150. Or in the
alternative, the top edge 12a of the lowermost groove, e.g., 12 of
the core is angularly reduced 12k to allow installation of the
segments with fingers 120 underneath the lower retaining ring 160.
See FIG. 19. Of course the fingers 120 of the segments, e.g.,
46-49, may also be present in plungers with grooved cores 12, 14,
16, with fingers interspersed in the core grooves. In that case, at
least one outer top edge of one of the grooves, e.g., 12, or
grooves, e.g., 12, 14, 16, is angularly reduced to allow
installation of the segments with fingers 120 underneath the
retaining rings, e.g., 150, 160.
[0064] Referring now to FIGS. 1, 20-25, the operation of an
additional embodiment of a plunger a will be explained. FIGS.
20-25, illustrate an alternate embodiment of the invention which in
many respects is the same as the embodiments of FIGS. 1-19. Similar
to the previous embodiments, the plunger of FIGS. 20, 23, 24, and
25 has a body with a core 10, but also has areas defined as a top
end 400, and a bottom end 500. The top end 400 has threading 430 to
which additional parts can be attached. In this embodiment, a
separate piece, such as a fishing part 420 is threadingly connected
to the body at a threaded connection 430. The top end fishing piece
420, like some of the previous embodiments, is provided with a head
area 425 and a reduced neck 424 for engagement by a fishing tool if
required. The bottom end 500 is provided with an external thread
435 to which additional parts can be attached such as a modified
end cap 220 with a corresponding internal thread 221, provides a
threaded connection between the body and the end cap 220. The
modified end cap 220 includes an enlarged chamber portion 510. The
plunger is also provided with an inner flow passage 460 which may
extend partway through or through the entire body and plunger, a
chamber 510, and a closure means 600. The major difference between
the plunger of FIGS. 2 and 18 and the previously described features
of FIGS. 2-19 is the inner flow passage 460 and the chamber 510 and
closure means 600. Like in the previously described embodiments,
the plungers of FIGS. 20-25 is provided with an outer seal means
made up of a plurality of segments, e.g., 46, 47, 48, 49, or 20-24,
which are substantially similar, if not identical, to the
corresponding elements in the embodiments of FIGS. 2-19. Retaining
rings 150 and 160 hold these segments 46, 47, 48, 49, or 20-24,
collectively the jacket assembly 100 in place but permit yet limit
outward radial movement between an innermost position 290, in which
the exterior cylindrical surfaces thereof lie has a diameter less
than that of any restriction to be encountered in the tubulars T
with which it is to be used, and an outermost position 300 in which
the exterior cylindrical surfaces, e.g., 46, 47, 48, 49 slidingly
and sealingly engage the walls of the tubulars T in which the
plunger P is to be used. Biasing means such as springs 190, bias
these segments toward their outermost position 300. The unique
circumferentially and mutually engageable tabs and slots and the
overlapping opposing tangentially disposed planar surfaces provided
by stepped areas, as in FIGS. 5, 6, 8, 14 thereon allow radial
inward and outward movement while limiting leakage and erosion
caused thereby.
[0065] As in the embodiments shown in FIGS. 2-19, the body of the
plunger also includes an internal sealing means, such as the inner
surfaces of the segments 61, 62, 63, 64, respectively, which may
also have rigid fingers 120 projecting inwardly. Or alternatively,
the raised surfaces may be in the form of a rigid band on the
surface of the core 11 (not shown). Preferably, each segment, e.g.,
46-49 has three fingers 120 on the underside of each segment 61,
62, 63, 64, which protrudes radially inward toward the core 10. The
fingers 120 of each segments, e.g., 46-49 are parallel and
horizontally aligned with the fingers of the adjacent segments so
the fingers collectively cooperate to encircle the core 10. As in
the previous embodiments, the preferred internal sealing means also
includes a core 10, wherein the surface 11 is grooved, e.g., 12,
14, 16. Where there are both grooves 12, 14, 16, in the surface of
the core 11 and fingers 120 on the segments 46, 47, 48, 49, the
fingers 120 are adjacent to and fit into the grooves 12, 14, 16, in
the core. The fingers 120 are typically separated from the core 10
unless the fingers are pushed to their most inward position.
Typically during operation, the fingers 120 and core 10 are
separated by a space, or flow path 200. This arrangement of grooves
and/or finger projections (or a band located on the core 10, not
shown) creates a tortuous path of flow that effects an inner
turbulent seal.
[0066] The chamber 510 which houses the closure means, such as a
stopper 600, is an enlarged area within the end cap 200. As
previously mentioned, the end cap 200 is threadingly connected to
the lower plunger body portion 500 at the threaded connection 435.
It may be inwardly tapered 221 below the chamber 510. The chamber
510 has a roof 520 at the upper end which may be inwardly tapered
221 below the roof 520, with an opening 525 in the roof which
communicates with the upper inner flow passage 460 and a floor 550
at the lower end with an opening into a bore which is typically
narrower than the flow passage 460 and which houses the stem 630
when the closure means is in the open position. Furthermore, there
is an opening 560 at the end of the stem bore flow passage 560 at
the bottom of the end cap 570, and the stem protrudes downward 670
from the body of the plunger in the open position. In the preferred
embodiment, the roof 520 of the chamber 510 is substantially curved
522 and has a stopper 600 with a head 615 whose top end 610 is
correspondingly curved 605, like the roof 520. Alternatively, the
roof 520 may be triangular in cross-section and the head of the
stopper is correspondingly cone-shaped. See FIGS. 24-25. There are
also other variations of additional shapes which the chamber roof
and chamber floor could possess, such as a flat roof and a curved
floor (not shown), and corresponding variations of the shape of the
first end and second end of the stopper, such as a flat top end and
a circular bottom end (not shown), which could also be
operable.
[0067] The roof 520 of the chamber 510 is further connected to a
downwardly facing and tapered seating surface 530. The area below
the seating surface 530 is also provided with an area partially
defined by a slanted or tapered ramp area 545 below the seating
surface 530. The seating surface 530 of the preferred embodiment is
sized and designed to receive and guide a plunger stopper closure
member 600 albeit rounded, half-sphere, or ball-type, upwardly to
the seating surface 605 in the roof 520. The plunger stopper 600
has a head 615 with a top end 610 and a bottom end 630, wherein the
bottom end of the stopper is substantially curved 635. Conversely,
the bottom end of the stopper may be substantially flat 630. A stem
650 which is rounded and has flat sides 652 and a substantially
rounded bottom 655 is attached to the bottom end 630 of the head
615. Alternatively, the top end 610 of the plunger stopper 600 may
further have a stem 630 which is attached to the top end 610 of the
head 615. This stem 680 will be pushed up into the inner flow
passage 460 above the chamber 510, when the bottom end 570 of the
plunger hits the bottom well stop means to further ensure closure
of the opening 525 into the flow passage 460. (See FIGS. 24, 25).
Under certain conditions, the stopper 600 is moveable between the
open position of FIG. 20, in which fluid and/or gas flow is
permitted into the inlet ports, e.g., 700, 702 in the end cap 220
through the chamber 510 and into the flow passage of the body 460,
through the hole 525 in the roof 520, and out through the outlet
ports, e.g., 715, 716, 717, 718 in the top end 400. In FIG. 21, the
stopper 600 is in a closed position in which the fluid and/or gas
flow through the chamber opening 545 into the flow passage 460 of
the plunger body is blocked by the top 610 of the stopper 600. In
the open position, the stem 650 extends downwardly through the
opening 555 in the hole in the floor 500 of the chamber 510 into
the bore 540 in the bottom of the end cap 560, and protrudes 670
from the lower end of the plunger body 570, when the plunger is
descending through the tubulars T, or at the surface once the
pressure valve V has been opened. When the stem 655 and then the
bottom end of the plunger reach the bottom of the well, or some
type of bottom well stop or well stop means SM, the stem 650 and
stopper head 615 is forced or pushed upwardly until the top end of
the head 610 is seated against the seating surface 530 of the roof
520 of the chamber 510.
[0068] The fishing part which is attached to the top end also has
an inner flow passage 460. In one embodiment, the inner flow
passage 460 also has an opening 720 at the top end of the plunger.
As previously discussed, the fishing part 420 may also have a
plurality of outlet ports 715, 716, 717, 718, or axial inner
passages, disposed around the sides of the collar 410 of the
fishing piece 420, in addition to, or instead of the opening at the
top end 720. Preferably, there are four radial ports, e.g., 715,
716, 717, 718 which are spaced along the cylindrical axis of the
collar at about 45 degrees from each other.
[0069] Similarly, there are preferably four radial ports which are
spaced along the cylindrical axis of the end cap 220 at about 45
degrees from each other 700, 701, 702, and 703. The location of the
inlet ports, e.g., 700, 702 in the chamber wall 511 of the end cap
220 are especially important. The ports 700, 702 are preferably
located so that the inside openings of the ports 710, 712 into the
chamber 510 are located above the top end 610 of the plunger
stopper head 615 when the stopper 600 is in its downward position.
Furthermore, these inlet ports are preferably located so that the
inside opening of the ports 710, 712 will be below the bottom end
630 of the stopper head 615 when the stopper is in its upward
position, closing the inner flow passage 460. This placement of the
inlet ports assures the bypassing of fluids through the chamber
passage 510 and into inner flow passage 460 as the plunger falls in
the tubulars T.
[0070] The plunger of the embodiment of FIGS. 20-24 also operates
much as the plunger embodiment of FIGS. 2-5 and 6-19, and may be
described with reference to FIG. 1. Like the plunger P of FIGS. 1,
and 2-19, the plunger of FIGS. 20-25 may be placed in the tubing
string T and allowed to fall or gravitate to the bottom of the well
W for producing the subterranean formation F thereof. However, it
will fall more rapidly due to the inner passage 460. When the
bottom end of the plunger 570 reaches the well stop or stop means,
the stem 650 of the closure means such as the stopper 600, and the
head member 615 are pushed upwardly toward the roof and to the
seating surface 530 and the closure means or stopper 600 is seated
against the roof 520. When the plunger P reaches the tubing stop SM
at the bottom of the tubulars, the weight of the plunger pushes
against the well stop SM forcing the stopper stem 650 and head 615
in an upward direction. As soon as the closure member 212 enters
the flow path of valve passage 202, 203, 205, the top end 710 of
the stopper 600 then proceeds past the ramp area 545 and up into
the seating surface 530 in the roof 520. Once the stopper 600 is
seated to assume its closed position seated, the flow of fluids
into the chamber through the inlet ports, e.g., 702, 710 will flow
up into the chamber 510 and against the second end of the plunger
head 530 will cause the stopper to assume and maintain its closed
position against the seating surface 530 as illustrated in FIGS.
23, 25. At this point, the bypassing of fluid through the flow
passage 460 is blocked and gas pressure is allowed to build up just
as with plunger 1 and 2 of the embodiment illustrated in FIGS. 2-4
and 5-19. After a preselected, predetermined period of time, the
control valve V at the surface is opened by the controller EC and
the gas pressure built up in the well causes the plunger and any
well fluids accumulated in the tubulars T thereabove to be elevated
to the surface and produced through the production or pay line PL.
Once the plunger is detected by sensor S and the control valve V
closed by the controller EC, pressure is equalized in the area of
the lubricating sub E. When that occurs the plunger stopper 600,
due to its own weight, falls back down and reassumes its open
position of FIGS. 20-24. This opens the inner flow passage 460,
allowing the plunger to descend to the bottom of the well W to
repeat the cycle.
[0071] The plunger of the present invention has a number of unique
elements. However, many variations of the invention can be made by
those skilled in the art without departing from the spirit of the
invention. Accordingly, it is intended that the scope of the
invention be limited only by the claims which follow. Of course,
the present invention is not intended to be restricted to any
particular form or arrangement, or any specific embodiment
disclosed herein, or any specific use, since the present invention
may be modified in various ways without departing from the spirit
or scope of the claimed invention herein. Furthermore, the figures
of the various embodiments is intended only for illustration and
for disclosure of operative embodiments and not to show all of the
various forms or modifications in which the present invention might
be embodied or operated. The present invention has also been
described in considerable detail in order to comply with the patent
laws by providing full public disclosure of at least one of its
forms. However, this detailed description is not intended to limit
the broad features or principles of the present invention in any
way, or to limit the scope of the patent monopoly to be
granted.
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