U.S. patent application number 16/694337 was filed with the patent office on 2021-05-27 for sand fallback submersible pump protection apparatus.
This patent application is currently assigned to The Cavins Corporation. The applicant listed for this patent is Roy Spence Arterbury, Michael Edwin Pollard. Invention is credited to Roy Spence Arterbury, Michael Edwin Pollard.
Application Number | 20210156225 16/694337 |
Document ID | / |
Family ID | 1000004524809 |
Filed Date | 2021-05-27 |
United States Patent
Application |
20210156225 |
Kind Code |
A1 |
Arterbury; Roy Spence ; et
al. |
May 27, 2021 |
SAND FALLBACK SUBMERSIBLE PUMP PROTECTION APPARATUS
Abstract
A sand fallback tool having an outer tubular body with proximal
end, a distal end, a chamber therebetween surrounding an axis
extending from the proximal end through the distal end, a tubular
flow divider supported within the chamber to divide at least a
portion of the chamber of the outer tubular body into a central
passage along the axis and an annular passage radially intermediate
an exterior of the tubular flow divider and an interior of the
outer tubular body, and an unobstructed axial settling path from
the proximal connector into the central passage. One embodiment
further includes a tubular extension coupled to the proximal
connector and extending along the axis to terminate at a distal end
of the tubular extension received within a proximal end of the
tubular flow divider to provide an "S"-shaped flow pathway
intermediate the annular passage and the proximal connector of the
outer tubular body.
Inventors: |
Arterbury; Roy Spence;
(Houston, TX) ; Pollard; Michael Edwin; (Houston,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Arterbury; Roy Spence
Pollard; Michael Edwin |
Houston
Houston |
TX
TX |
US
US |
|
|
Assignee: |
The Cavins Corporation
Houston
TX
|
Family ID: |
1000004524809 |
Appl. No.: |
16/694337 |
Filed: |
November 25, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 2200/04 20200501;
E21B 43/128 20130101; E21B 34/08 20130101 |
International
Class: |
E21B 34/08 20060101
E21B034/08; E21B 43/12 20060101 E21B043/12 |
Claims
1. A sand fallback tool, comprising: an elongate outer tubular body
having an axis, a proximal end with a proximal connector for
coupling to a production string, a distal end with a distal
connector for coupling to a submersible pump, and an elongate
chamber within the outer tubular body surrounding the axis and
disposed axially intermediate the proximal end and the distal end
of the outer tubular body; and a tubular flow divider having a
proximal end and a distal end, the tubular flow divider supported
within the chamber of the outer tubular body in a position to
surround the axis and to divide at least a portion of the chamber
into a central passage and an annular passage disposed radially
intermediate the flow passage divider and the outer tubular body,
the central passage of the tubular flow divider being axially
aligned with the proximal end of the outer tubular body to provide
an unobstructed axial settling path; wherein during interruptions
in a power supply to the submersible pump, sand entrained in fluid
residing in the production string will settle from the production
string through the unobstructed axial settling path into the
central passage of the tubular flow divider.
2. The sand fallback tool of claim 1, further comprising: a tubular
extender coupled to the proximal connector and extending along the
axis into the proximal end of the tubular flow divider.
3. The sand fallback tool of claim 1, further comprising: a distal
check valve disposed within the chamber of the outer tubular body
and axially intermediate a distal end of the tubular flow divider
and the distal connector of the outer tubular body.
4. The sand fallback tool of claim 3, wherein the distal check
valve includes: a seat within the chamber proximal to the distal
end of the outer tubular body, the seat surrounding a bore to
receive fluid flow from a submersible pump coupled to the distal
connector, the fluid flow entering the chamber of the outer tubular
body through the distal connector of the outer tubular body; and a
flow stop member shaped for sealed engagement with the seat of the
distal check valve, the flow stop member captured within the
chamber intermediate the seat and the distal end of the flow
passage divider and movable within the chamber between a seated
position in sealed engagement with the seat, to prevent fluid flow
from the chamber of the outer tubular body through the distal
connector, and an open position with the flow stop member displaced
from the seat to permit fluid flow from the submersible pump
coupled to the distal end of the outer tubular body into the
chamber of the outer tubular body.
5. The sand fallback tool of claim 4, wherein the distal check
valve further includes: a cage surrounding the seat to limit a
range of movement of the flow stop member relative to the seat.
6. The sand fallback tool of claim 1, further comprising: a
proximal check valve within the central passage of the tubular flow
divider and proximal to the distal end of the tubular flow
divider.
7. The sand fallback tool of claim 6, wherein the proximal check
valve includes: a seat within the central passage; and a flow stop
member shaped for sealed engagement with the seat of the distal
check valve, the flow stop member captured within the central
passage intermediate the seat and the proximal end of the tubular
flow divider, the flow stop member movable within the central
passage between a seated position in sealed engagement with the
seat and an open position with the flow stop member displaced from
the seat to permit fluid flow from the submersible pump coupled to
the distal end of the outer tubular body into the distal end of the
tubular flow divider and through the central passage during
operation of the submersible pump.
8. The sand fallback tool of claim 1, further comprising: a necked
portion of the central passage of the tubular flow divider proximal
to the distal end of the tubular flow divider.
9. The sand fallback tool of claim 1, further comprising: a necked
portion of the central passage of the tubular flow divider proximal
do the distal end of the tubular flow divider; wherein the necked
portion of the central passage promotes bridging of settled sand at
the necked portion and subsequent accumulation of a column settled
sand atop the bridged sand at the necked portion.
10. The sand fallback tool of claim 1, further comprising: a
resiliently deformable funnel member coupled to the proximal end of
the tubular flow divider shaped as an upwardly expanding section of
a cone, the resiliently deformable funnel member having an original
configuration to guide settling sand entering the outer tubular
body through the proximal connect into the central passage and a
collapsed configuration to allow fluid flowing upwardly in the
annular passage surrounding the tubular flow divider to flow
radially inwardly from the annular passage to the proximal
connector.
11. The sand fallback tool of claim 10, wherein the resiliently
deformable funnel member comprises rubber.
12. The sand fallback tool of claim 1, wherein the tubular flow
divider is supported from one of the proximal end of the tubular
flow divider and the distal end of the tubular flow divider.
13. A sand fallback tool, comprising: an elongate outer tubular
body having a proximal end with a proximal connector, a distal end
with a distal connector, an axis extending from the proximal
connector to the distal connector, and an elongate chamber
intermediate the proximal end and the distal end of the outer
tubular body; and a tubular flow divider supported within the
chamber to surround the axis and to divide at least a portion of
the chamber into a central passage about the axis and an annular
passage surrounding the tubular flow divider; and an unobstructed
axial settling path from the proximal connector into the central
passage to allow sand settling into the sand fallback tool through
the proximal connector to move into the central passage of the
tubular flow divider with the sand fallback tool with the axis
being vertically aligned; wherein during interruptions in a power
supply to the submersible pump, sand entrained in fluid residing in
a production string coupled to the proximal connector will settle
from the production string through the unobstructed axial settling
path into the central passage of the tubular flow divider.
14. The sand fallback tool of claim 13, further comprising: a
distal check valve disposed within the chamber and proximal to the
distal connector, the distal check valve having a closed position
to prevent fluid flow from the chamber through the distal connector
and an open position to allow fluid flow from a submersible pump
coupled to the distal connector into the chamber.
15. The sand fallback tool of claim 13, further comprising: a
proximal check valve disposed within the central passage, the
proximal check valve having a closed position to prevent flow from
a distal end of the central passage and an open position to allow
fluid flow from the distal connector through the distal end of the
central passage into the central passage.
16. The sand fallback tool of claim 13, further comprising: a
resiliently deformable funnel member coupled to a proximal end of
the tubular flow divider, the funnel member having a relaxed
configuration in which it guides settling sand entering the sand
fallback tool through the proximal connector into the central
passage and a collapsed configuration to allow fluid flowing within
the annular passage from the distal connector towards the proximal
connector to flow radially inwardly to the proximal connector.
17. The sand fallback tool of claim 16, wherein the funnel member
is shaped as an upwardly expanding section of a cone.
18. The sand fallback tool of claim 17, wherein the funnel member
comprises rubber.
19. The sand fallback tool of claim 13, wherein the tubular flow
divider is supported within the chamber from one of the proximal
end and the distal end.
20. The sand fallback tool of claim 13, further comprising a cage
proximal to the distal connector.
Description
BACKGROUND
Field of the Invention
[0001] The present invention relates to a sand fallback tool that
provides protection against unwanted damage to or incapacitation of
downhole submersible pumps used to recover formation fluids from
subsurface geologic formations through artificial lift. The present
invention is directed to a sand fallback tool that prevents sand
from settling out of fluids standing in a stagnant production
string back onto or into a submersible artificial lift pump.
Unwanted sand intrusion into the submersible pump can damage or
disable the submersible pump and prevent it from being successfully
restarted for continued fluid production to the surface.
Background of the Related Art
[0002] Some subsurface geologic formations produce fluids with
entrained sand. The sand can cause problems with production
equipment. For example, entrained sand will settle from the fluid
in which it is entrained upon interruption of a submersible pump
used to pump fluids entering a well from fluid-bearing subsurface
geologic formations to the surface. This is called sand fallback.
The settling sand can settle in an inactive submersible pump and
clog or otherwise impair restoration of operation of the pump.
[0003] Sand fallback generally occurs when electrical current to a
submersible pump is interrupted causing sand entrained in the fluid
that was flowing up a production string at the time of the
interruption to settle. Settling sand can enter and damage and/or
obstruct restoration of the operation of the submersible pump
rotors upon reactivation of the pump.
[0004] Some prior art sand fallback tools include movable
components that are often connected through linkages or mechanisms
one to the others. Such connected linkages and mechanisms may
become clogged, obstructed or otherwise incapacitated by settling
sand, thereby preventing smooth restoration of submersible pump
operation and resumption of fluid production from the well.
[0005] One prior art sand fallback tool includes a tubular flow
divider to divide a chamber within the sand fallback tool into a
central passage and an annular passage, and a diverter disposed
adjacent to a proximal connection that couples to a production
string. The diverter causes sand settling back into the sand
fallback tool during interruptions in the operation of the
submersible pump to be diverted in the annular passage, thereby
leaving the central passage open for restoration of fluid flow upon
reactivation of the submersible pump. Settled sand is thereby
accumulated and stored in the annular passage upon interruption of
operation of the submersible pump coupled to a distal end of the
sand fallback tool.
[0006] Sand fallback tools are generally elongate tools that are
coupled to a submersible pump at a distal connector, coupled to the
production string at a proximal connector, and positioned within a
well in a vertical orientation so that sand settling out of fluid
residing in a stagnant production string is prevented from settling
into an inactive submersible pump coupled to the distal
connector.
SUMMARY
[0007] Embodiments of the sand fallback tool of the present
invention are adapted to be coupled to a distal end of a tubular
production string and positioned in a well in a vertical
orientation. Embodiments of the sand fallback tool include a distal
end adapted for being coupled to a proximal end of a submersible
pump, also known as an electrical submersible pump (ESP).
Embodiments of the sand fall back tool of the present invention
prevent settling sand from entering into the proximal end of a
submersible pump coupled to the distal end of the sand fallback
tool.
[0008] Some embodiments of the sand fallback tool of the present
invention include movable components that are not physically
connected to other movable or immovable components of the tool, but
are instead dynamically displaceable by fluid flow within a cage,
channel or a chamber in which the movable component can move. Some
embodiments of the sand fallback tool of the present invention
include one or more check valves that open to allow the flow of
fluid, with sand entrained therein, through the sand fallback tool
and upwardly into a production tubing through which the fluid flows
to the surface during operation of a submersible pump. These check
valves will later close to prevent unwanted backflow of fluid and
unwanted settling of sand into the submersible pump that is coupled
to the distal end of the sand fallback tool when the submersible
pump may become inactive.
[0009] Embodiments of the sand fallback tool of the present
invention include a proximal end with a threaded proximal connector
for threadedly coupling the sand fallback tool to a distal end of a
tubular string that can be stepwise extended into an earthen well
to position and support the sand fallback tool and a submersible
pump coupled thereto, and a distal end with a threaded distal
connector for threadedly coupling to a proximal end (discharge end)
of a submersible pump. "Coupling," as that term is used herein,
means that the production tubing and the sand fallback tool, or the
sand fallback tool and the submersible pump, may be directly
coupled, and it also means that other tools may be coupled
intermediate the proximal end of the sand fallback tool and the
production tubing or between the distal end of the sand fallback
tool and the submersible pump without loss of benefit and use of
the sand fallback tool. More than one sand fallback tool can be
included within the same tool string for enhanced protection
against unwanted sand entry into the submersible pump.
[0010] The distal connector of embodiments of the sand fallback
tool has a bore for the upwardly passage of fluids entering the
sand fallback tool from the submersible pump coupled to the distal
connector. The proximal connector of embodiments of the sand
fallback tool has a bore for passage of fluids exiting the sand
fallback tool to then enter a production tubing coupled to the
proximal connector of the sand fallback tool. Embodiments of the
sand fallback tool include a central chamber that is aligned with
the proximal connector of the sand fallback tool and that can
receive and store settling sand without obstruction or closing of
an annular passage that surrounds the central chamber. The annular
passage can, when the central passage is obstructed with settled
sand, provide a fluid flow passage to bypass the obstructed central
passage and allow the submersible pump to be restarted and operated
until the settled sand obstruction can be cleared from the central
passage.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0011] FIG. 1 is a cross-sectional elevation view of an embodiment
of the sand fallback tool of the present invention.
[0012] FIG. 2 is the cross-sectional elevation view of the
embodiment of the sand fallback tool of FIG. 1 after interruption
of the power supply to the submersible pump (not shown) and after
settling sand has settled from the stagnant fluid in the production
tubing (not shown) above the tool through the proximal connector
and into the central passage of the tool to accumulate on the flow
stop member of the check valve therewithin.
[0013] FIG. 3 is the cross-sectional elevation view of an
embodiment of the sand fallback tool of FIGS. 1 and 2 after
restoration of power to the submersible pump and resumption of
fluid flow upwardly through the tool.
[0014] FIG. 4 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool of the present invention.
[0015] FIG. 5 is the cross-sectional elevation view of the
embodiment of the sand fallback tool of FIG. 4 after interruption
of the power supply to the submersible pump (not shown) and after
settling sand has settled from the stagnant fluid in the production
tubing (not shown) above the tool through the proximal connector
and into the central passage of the tool to accumulate on the flow
stop member of the check valve therewithin.
[0016] FIG. 6 is the cross-sectional elevation view of an
embodiment of the sand fallback tool of FIGS. 4 and 5 after
restoration of power to the submersible pump and resumption of
fluid flow upwardly through the tool.
[0017] FIG. 7 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool of the present invention.
[0018] FIG. 8 is the cross-sectional elevation view of the
embodiment of the sand fallback tool of FIG. 7 after interruption
of the power supply to the submersible pump (not shown) and after
settling sand has settled from the stagnant fluid in the production
tubing (not shown) above the tool through the proximal connector
and into the central passage of the tool to accumulate on the flow
stop member of the check valve therewithin.
[0019] FIG. 9 is the cross-sectional elevation view of an
embodiment of the sand fallback tool of FIGS. 7 and 8 after
restoration of power to the submersible pump and resumption of
fluid flow upwardly through the tool.
[0020] FIG. 10 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool of the present invention.
[0021] FIG. 11 is the cross-sectional elevation view of the
embodiment of the sand fallback tool of FIG. 10 after interruption
of the power supply to the submersible pump (not shown) and after
settling sand has settled from the stagnant fluid in the production
tubing (not shown) above the tool through the proximal connector
and into the central passage of the tool to accumulate on the cage
below the central passage and proximal to the distal end of the
tool that houses the flow stop member of the check valve
therewithin.
[0022] FIG. 12 is the cross-sectional elevation view of an
embodiment of the sand fallback tool of FIGS. 10 and 11 after
restoration of power to the submersible pump and resumption of
fluid flow upwardly through the tool.
[0023] FIG. 13 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool of the present invention.
[0024] FIG. 14 is the cross-sectional elevation view of the
embodiment of the sand fallback tool of FIG. 13 after interruption
of the power supply to the submersible pump (not shown) and after
settling sand has settled from the stagnant fluid in the production
tubing (not shown) above the tool through the proximal connector
and into the central passage of the tool to accumulate on the flow
stop member of the check valve therewithin.
[0025] FIG. 15 is the cross-sectional elevation view of an
embodiment of the sand fallback tool of FIGS. 13 and 14 after
restoration of power to the submersible pump and resumption of
fluid flow upwardly through the tool.
[0026] FIG. 16 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool of the present invention.
[0027] FIG. 17 is the cross-sectional elevation view of the
embodiment of the sand fallback tool of FIG. 16 after interruption
of the power supply to the submersible pump (not shown) and after
settling sand has settled from the stagnant fluid in the production
tubing (not shown) above the tool through the proximal connector
and into the central passage of the tool to accumulate on the flow
stop member of the check valve therewithin.
[0028] FIG. 18 is the cross-sectional elevation view of an
embodiment of the sand fallback tool of FIGS. 16 and 17 after
restoration of power to the submersible pump and resumption of
fluid flow upwardly through the tool.
[0029] FIG. 19 is a cross-sectional elevation view of an embodiment
of the sand fallback tool of the present invention.
[0030] FIG. 20 is the cross-sectional elevation view of the
embodiment of the sand fallback tool of FIG. 19 after interruption
of the power supply to the submersible pump (not shown) and after
settling sand has bridged and then settled from the stagnant fluid
in the production tubing (not shown) above the tool through the
proximal connector and into the central passage of the tool to
accumulate therewithin.
[0031] FIG. 21 is the cross-sectional elevation view of an
embodiment of the sand fallback tool of FIGS. 19 and 20 after
restoration of power to the submersible pump and resumption of
fluid flow upwardly through the tool.
DETAILED DESCRIPTION
[0032] Embodiments of the sand fallback tool of the present
invention provide a substantial amount of storage and retention
space for settled sand so that the settled sand does not enter and
possible clog or otherwise disable a submersible pump coupled to
the distal end of the sand fallback tool. Embodiments of the sand
fallback tool include an unobstructed axial settling path from a
proximal connector of the tool downwardly into a central passage of
the tool within the tubular flow divider. The advantages of this
structure will be apparent from the discussion that follows.
[0033] FIG. 1 is a cross-sectional elevation view of an embodiment
of the sand fallback tool 10 of the present invention. The sand
fallback tool 10 of FIG. 1 comprises an elongate outer tubular body
12 having a proximal end 22 with a proximal connector 26 for
coupling the sand fallback tool 10 to a string of production tubing
(not shown), a distal end 24 with a distal connector 25 for
coupling to a submersible pump (not shown), and a chamber 11 within
the outer tubular body 12 axially between the proximal connector 26
and the distal connector 25. The chamber 11 within the outer
tubular body 12 is divided into portions by a tubular flow divider
14 having a distal end 15, a central passage 16 within the tubular
flow divider 14, and a proximal end 17. The tubular flow divider 14
of the sand fallback tool 10 of FIG. 1 is supported within the
chamber 11 of the outer tubular body 12 centrally about the axis 13
to divide the portion of the chamber 11 in which the tubular flow
divider 14 is supported into two flow passages through which fluid
entering the distal connector 25 may flow to and through the
proximal connector 26. The two flow passages include a central
passage 16 disposed within the flow divider 14 and surrounding the
axis 13 and the annular passage 18 radially intermediate the
tubular flow divider 14 and the outer tubular body 12. The tubular
flow divider 14 of the embodiment of the sand fallback tool 10 of
FIG. 1 is supported within the chamber 11 of the outer tubular body
12 from the proximal end 17 of the tubular flow divider 14, but may
in other embodiments be supported from the distal end 15 or from
some other location along the tubular flow divider 14.
[0034] The embodiment of the sand fallback tool 10 of FIG. 1
further includes a distal check valve 31 having a cage 30 disposed
within the chamber 11 of the outer tubular body 12 proximal to the
distal connector 25 and a flow stop member 34 movably captured
within the cage 30. The cage 30 of the distal check valve 31
includes a plurality of holes 32 through which fluid entering the
chamber 11 through the distal connector 25 flows with the distal
check valve 31 in the open position illustrated in FIG. 1. The
distal check valve 31 of FIG. 1 further includes a seat 21 disposed
within the chamber 11 of the outer tubular body 12, the seat 21
sized for sealed engagement with the flow stop member 34. FIG. 1
illustrates an embodiment of a sand fallback tool 10 having a
distal check valve 31 that includes a flow stop member 34 that is
spherical in shape, but in other embodiments of the sand fallback
tool 10 of the present invention the flow stop member 34 may be an
elongate plug with a tapered nose, such as a conical shape, or any
other shape that can maintain a proper orientation within the cage
30 and then sealably engage the seat 21 of the distal check valve
31 upon closure to prevent unwanted fluid flow or settling sand to
pass from the chamber 11 through the distal connector 25 and into a
submersible pump (not shown) coupled to the distal connector 25
during interruptions of operation of the submersible pump. The flow
stop member 34 may be of a material for providing to the flow stop
member 34 a combination of density and surface friction to fluid
flow there around so that the flow stop member 34 sinks to engage
the seat 21 upon termination of operation of the submersible pump
(not shown) coupled to the distal connector 25 and the flow stop
member 34 is displaced upwardly and off of the seat 21 by
application of fluid pressure and fluid flow entering the chamber
11 through the distal connector 25 during operation of the
submersible pump.
[0035] The central passage 16 of the tubular flow divider 14 of the
embodiment of the sand fallback tool 10 of FIG. 1 further includes
a distal necked portion 52 proximal to the distal end 15 of the
tubular flow divider 14 that is smaller in size than an adjacent
portion 53 of the central passage 16. The central passage 16
includes a proximal check valve 51 including the distal necked
portion 52 and a proximal flow stop member 54 within the central
passage 16. The proximal check valve 51 is illustrated in FIG. 1 in
the open position to allow fluid flow to pass upwardly through the
central passage 16 and around the proximal flow stop member 54 of
the proximal check valve 51. The proximal check valve 51 further
includes a seat 55 within the distal necked portion 52 of the
central passage 16 of the tubular flow divider 14, the seat 55
being shaped for sealed engagement with the proximal flow stop
member 54 with the proximal check valve 51 in the closed position.
As with the distal check valve 31, the proximal flow stop member 54
engages the seat 55 to prevent fluid and settled sand from flowing
from the central passage 16 through the distal end 15 of the
tubular flow divider 14. The embodiment of the sand fallback tool
10 of FIG. 1 further includes a tubular extension 63 coupled to the
proximal connector 26 of the outer tubular body 12 and extending
distally into the chamber 11 and into the central passage 16 of the
tubular flow divider 14 to dispose a distal end 64 of the tubular
extension 63 within the proximal end 17 of the tubular flow divider
14 and within the central passage 16. The distal end 64 of the
tubular extension 63 serves to limit the range of movement of the
proximal flow stop member 54 within the central passage 16 when the
proximal flow stop member 54 is displaced from the seat 55 by fluid
pressure applied to the proximal flow stop member 54 by operation
of the submersible pump (not shown) coupled to the distal connector
25 of the sand fallback tool 10. The tubular extension 63 and the
tubular flow divider 16 cause fluid flowing upwardly within the
annular passage 18 to flow through an "S"-shaped pathway defined by
the distal end 64 of the tubular extension 63 and the proximal end
17 of the tubular flow divider 14 into which the distal end 64 is
disposed. During operation of the sand fallback tool 10, fluid
moves within the annular passage 18 upwardly towards the proximal
end 22 of the outer tubular body 12 to the proximal end 17 of the
tubular flow divider 14, then radially inwardly through the holes
61 adjacent to the proximal end 17 of the tubular flow divider 14,
then downwardly between the tubular extension 63 and the tubular
flow divider 14 to the holes 65 within the tubular extension 63,
and then radially inwardly into the tubular extension 63 to
commingle with fluid flowing upwardly from the central passage 16
(if any) of the tubular flow divider 14 and then from the sand
fallback tool 10 through the proximal connector 26. The tubular
extension 63 extends a bore 26A of the proximal connector 26
downwardly into the proximal end 17 of the tubular flow divider 14.
This structure substantially prevents settling sand that may enter
the sand fallback tool 10 through the proximal connector 26 during
interruptions of operation of the submersible pump (not shown), and
causes sand to settle within the central passage 16 of the tubular
flow divider 14 instead of settling within the annular passage 18,
as will be discussed in more detail in connection with FIG. 2.
[0036] FIG. 2 is the cross-sectional elevation view of the
embodiment of the sand fallback tool 10 of FIG. 1 after
interruption of a power supply to the submersible pump (not shown)
that moves fluid upwardly through the sand fallback tool 10 and
after an amount of settling sand 57 has settled from a now-stagnant
column of produced fluid residing in a string of production tubing
(not shown) coupled to the proximal connector 26 and disposed above
the sand fallback tool 10. As described above, the proximal flow
stop member 54 of the proximal check valve 51 engages the seat 55
of the proximal check valve 51 upon interruption of the power
supply and the distal flow stop member 34 of the distal check valve
31 engages the seat 21 of the distal check valve 31 due to the
density of the proximal flow stop member 54 and the distal flow
stop member 34 being greater than the density of the fluid produced
through the sand fallback tool 10. FIG. 2 shows the settled sand 57
that settles downwardly from the production tubing and that enters
the sand fallback tool 10 through the proximal connector 26, then
through the tubular extension 63 extending downwardly therefrom,
and into the central passage 16 of the tubular flow divider 14 to
accumulate within the central passage 16 and atop the proximal flow
stop member 54 engaged with the seat 55 of the proximal check valve
51. There is an unobstructed axial settling path 99 from the
proximal connection 26 into the central passage 16 of tubular
divider 14 that is supported within the chamber 11 of the outer
tubular body 12. The unobstructed axial settling path 99 permits
settling sand 57 to accumulate within the central passage 16
without blocking the annular passage 18, thereby permitting at
least some fluid flow upon restoration of electrical power to the
submersible pump that moves fluid upwardly through the sand
fallback tool 10. The fluid flow provided by maintaining a clear
annular passage 18 enables well production to be restored without
damaging the submersible pump, which can be damaged by operation of
the pump without some minimal amount of fluid throughput.
[0037] As illustrated in FIG. 2, the annular passage 18 remains
open and unobstructed by settled sand 57 due to the alignment of
the central passage 16 of the tubular flow divider 14 with the
tubular extension 63 and the distal end 64 of the tubular extension
63 being disposed below the proximal end 17 of the tubular flow
divider 14 to create the "S"-shaped flowpath. The sizes of the
tubular extension 63 and the central passage 16 into which the
tubular extension 63 extends can be selected to provide a desired
pressure drop resisting the flow of fluid up the annular passage 18
of the sand fallback tool 10 so that there is a pressure
differential from the annular passage 18 into the central passage
16 of the tubular flow divider 14. In some embodiments of the sand
fallback tool 10 of the present invention, such as the one
discussed below in relation to FIGS. 7-9, this pressure
differential provides for leakage of pressurized fluid from the
annular passage 18 through one or more apertures in tubular flow
divider 14 into the central passage 16 of the tubular flow divider
14 to unsettle and/or fluidize an otherwise stagnant column of
settled sand 57 therein. Upon removal of the sand fallback tool 10
from a well to the surface, apertures in the tubular flow divider
14 may also serve to relieve pressurized pockets of gas that may
become trapped in the settled sand 57 that accumulates within the
central passage 16 of the tubular flow divider 14. Embodiments of
the present invention of the sand fallback tool 10 having one or
more apertures in the tubular flow divider 14 are discussed in
greater detail below in connection with FIGS. 7-9.
[0038] FIG. 3 is the cross-sectional elevation view of the
embodiment of the sand fallback tool 10 of FIGS. 1 and 2 after
restoration of power to the submersible pump (not shown) coupled to
the distal connector 25 of the sand fallback tool 10 and resumption
of fluid flow upwardly through the sand fallback tool 10. Upon
restoration of the operation of the submersible pump, fluid
pressure initially bears against and displaces the flow stop member
34 of the distal check valve 31 from the seat 21 to provide fluid
flow from the submersible pump, through the distal connector 25,
through the holes 32 of the cage 30 of the distal check valve 31,
through the annular passage 18, through the "S"-shaped flow path
formed by the tubular extender 63 and the proximal end 17 of the
tubular flow divider 14, through the holes 65 in the tubular
extension 63 to exit from the sand fallback tool 10 by way of the
proximal connector 26. As flow through this fluid flow path defined
by these structures occurs, the turbulence of the fluid flow causes
unsettling and fluidization of the column of settled sand 57 within
the central passage 16. At first, small amounts of the settled sand
57 begin to become entrained in the fluid flow emerging from the
annular passage 18 and leaving the sand fallback tool 10 through
the proximal connector 26. As the column lightens, fluid pressure
bearing against the flow stop member 54 of the proximal check valve
51 eventually displaces the flow stop body 54 from the seat 55 and
fluid begins to flow into the distal end 15 of the tubular flow
divider 14, around the flow stop member 54 and through the column
of settled sand 57, thereby further entraining sand in the fluid
flow exiting the sand fallback tool 10 at the proximal connector
26.
[0039] FIG. 4 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool 10 of the present invention.
The alternate embodiment of the sand fallback tool 10 illustrated
in FIGS. 4-6 resembles the embodiment of the sand fallback tool 10
of FIGS. 1-3 except that instead of using a cylindrical cage 30 to
limit the movement of the flow stop member 34 of the distal check
valve 31 as shown in FIGS. 1-3, the embodiment of the sand fallback
tool 10 of FIGS. 4-6 includes an alternative type of cage that
includes a larger portion of the chamber 11 from the seat 21 to a
permeable divider 33 such as, for example, a grate having a
plurality of holes in it, to limit the range of movement of the
flow stop member 34 while allowing fluid to pass there through. The
substitution of the permeable divider 33 shown in FIGS. 4-6 for the
conventional cage 30 shown in FIGS. 1-3 does not impair the benefit
provided by embodiments of the sand fallback tool 10 of the present
invention. Similarly, the alternate embodiment of the sand fallback
tool 10 illustrated in FIGS. 4-6 resembles the embodiment of the
sand fallback tool 10 of FIGS. 1-3 except that instead of having
holes 65 in the tubular extension 63 to permit continuing fluid
flow into the tubular extension 63 when the flow stop member 54 of
the proximal check valve 51 engages the distal end 64 of the
tubular extension 63, as illustrated in FIG. 1, the tubular flow
divider 14 of the embodiment of the sand fallback tool 10 of FIGS.
4-6 includes a permeable divider 58 to limit the movement of the
flow stop member 54 of the proximal check valve 51 as shown in
FIGS. 4-6, thereby making the holes 65 in the tubular extension 63
(as shown in FIG. 1) unnecessary because the flow stop member 54 of
the proximal check valve 51 of the embodiment of the sand fallback
tool 10 of FIG. 4 is prevented by the permeable divider 58 from
engaging and closing the distal end 64 of the tubular extension 63
to fluid flow.
[0040] The sand fallback tool 10 of FIG. 4 further comprises an
elongate outer tubular body 12 having a proximal end 22 with a
proximal connector 26 for coupling the sand fallback tool 10 to
production tubing (not shown), a distal end 24 with a distal
connector 25 for coupling to a submersible pump (not shown), and a
chamber 11 within the outer tubular body 12 between the proximal
connector 26 and the distal connector 25. The chamber 11 within the
outer tubular body 12 is divided into portions by a tubular flow
divider 14 having a distal end 15, a central passage 16 within the
tubular flow divider 14, and a proximal end 17. The tubular flow
divider 14 of the sand fallback tool 10 of FIG. 4 is supported
within the chamber 11 of the outer tubular body 12 centrally about
the axis 13 to divide the portion of the chamber 11 in which the
tubular flow divider 14 is supported into two flow passages through
which fluid entering the distal connector 25 may flow to the
proximal connector 26. The two flow passages include a central
passage 16 disposed within the flow divider 14 and surrounding the
axis 13 and the annular passage 18 radially intermediate the
tubular flow divider 14 and the outer tubular body 12. As with the
embodiment of FIGS. 1-3, the tubular flow divider 14 of the
embodiment of the sand fallback tool 10 of FIG. 4-6 is supported
within the chamber 11 of the outer tubular body 12 from the
proximal end 17 of the tubular flow divider 14, but may in other
embodiments be supported from the distal end 15 or from some other
location along the tubular flow divider 14.
[0041] The sand fallback tool 10 of FIG. 4 further includes a
distal check valve 31 having a permeable divider 33 disposed within
the chamber 11 of the outer tubular body 12 proximal to the distal
connector 25 and a flow stop member 34 movably captured below the
permeable divider 33. The permeable divider 33 of the distal check
valve 31 may include a plurality of holes or slots therein through
which fluid entering the chamber 11 through the distal connector 25
flows with the distal check valve 31 in the open position
illustrated in FIG. 4. The distal check valve 31 of FIG. 4 further
includes a seat 21 disposed within the chamber 11 of the outer
tubular body 12, the seat 21 sized for sealed engagement with the
flow stop member 34 as discussed below in connection with FIG. 5.
FIG. 4 illustrates a flow stop member 34 that is spherical in
shape, but in other embodiments of the sand fallback tool 10 of the
present invention, the flow stop member 34 can be an elongate plug
with a tapered nose, a conical shape, or any other shape that can
maintain proper orientation within the chamber 11 and then sealably
engage the seat 21 of the distal check valve 31 to prevent unwanted
fluid flow or sand passage from the central passage 16 through the
distal connector 25 and into the submersible pump (not shown)
connected thereto during interruptions of operation of the
submersible pump. The flow stop member 34 may be of a material for
providing to the flow stop member 34 a combination of size, weight
and surface friction to be displaced from the seat 21 and to
thereby permit fluid flow around the flow stop member 34 and in the
upwardly direction through the permeable divider 33 so that the
flow stop member 34 drops or settles within the central passage 16
to sealably engage the seat 21 upon termination of operation of the
submersible pump (not shown), and the flow stop member 34 is
displaced from the seat 21 by fluid pressure and flow of fluid
entering the chamber 11 through the distal connector 25 during
operation of the submersible pump.
[0042] The central passage 16 of the tubular flow divider 14 of the
sand fallback tool 10 of FIG. 4 further includes a distal necked
portion 52 proximal to the distal end 15 of the tubular flow
divider 14 that is smaller in size than an adjacent portion 53 of
the central passage 16 distal to the distal end 15 of the tubular
flow divider 14. The central passage 16 proximal to the distal end
15 further includes a proximal check valve 51 including the distal
necked portion 52 and a proximal flow stop member 54 movable within
the central passage 16. The proximal check valve 51 further
includes a seat 55 within the tubular flow divider 14 at or
adjacent to the distal necked portion 52 that is shaped for sealed
engagement with the proximal flow stop member 54. As with the
distal check valve 31, the proximal flow stop member 54 of the
proximal check valve 51 sealably engages the seat 55 to prevent
fluid and settled sand from flowing downwardly from the central
passage 16 through the distal end 15 of the tubular flow divider
14. The embodiment of the sand fallback tool 10 of FIG. 4 further
includes a permeable divider 58 within the adjacent portion 53 of
the central passage 16 to limit the movement of the flow stop
member 54 within the central passage 16 during operation of the
submersible pump. The sand fallback tool 10 of FIG. 4 further
includes a tubular extension 63 coupled to the proximal connector
26 of the outer tubular body 12 and extending distally into the
chamber 11 and into the proximal end 17 of the tubular flow divider
14. The distal end 64 of the tubular extension 63 is disposed
within the central passage 16. The tubular extension 63 and the
tubular flow divider 14 cause fluid flowing within the annular
passage 18 to flow through an "S"-shaped pathway disposed at the
proximal end 17 of the flow passage divider 14 and along the
tubular extension 63 as described above in relation to FIGS. 1-3.
Upon restoration of the operation of the submersible pump, the flow
of fluid within the annular passage 18 during operation of the
submersible pump (not shown) coupled to the distal connector 25
flows upwardly through the distal connector 25, through the annular
passage 18 to the proximal end 17 of the tubular flow divider 14,
passes radially inwardly through the holes 61 therein, flows
downwardly along the tubular extension 63 and then radially
inwardly into the distal end 64 of the tubular extension 63 to mix
with fluid flowing from the central passage 16 (if any) and then
the fluid exits from the sand fallback tool 10 through the proximal
connector 26. The tubular extension 63 extends the bore 26A of the
proximal connector 26 downwardly into the central passage 16 of the
tubular flow divider 14. This arrangement causes settling sand 57
that may enter the sand fallback tool 10 through the proximal
connector 26 to settle within the central passage 16 of the tubular
flow divider 14 instead of settling within the annular passage 18,
as will be discussed in more detail in connection with FIG. 5.
[0043] FIG. 5 is the cross-sectional elevation view of the
embodiment of the sand fallback tool 10 of FIG. 4 after
interruption of the power supply to the submersible pump (not
shown) and after settling sand 57 has settled from the stagnant
fluid in the production tubing (not shown) above the sand fallback
tool 10 through the proximal connector 26, through the tubular
extension 63 and into the central passage 16 of the sand fallback
tool 10 to accumulate a column 59 of settled sand 57 atop the flow
stop member 54 of the proximal check valve 51, which is shown in
the closed position. There is an unobstructed axial settling path
99 from the proximal connection 26 into the central passage 16 of
tubular divider 14 that is supported within the chamber 11 of the
outer tubular body 12. It can be seen in FIG. 5 how the settled
sand 57 has settled through the permeable divider 58 (or grate)
that limits movement of the flow stop member 54 and onto the seated
flow stop member 54 as it sealably engages the seat 55. The tubular
extension 63 of the embodiment of the sand fallback tool 10 of
FIGS. 4-6 does not contain holes 65 as does the embodiment of the
sand fallback tool 10 of FIG. 1-3 because the divider 58 prevents
the flow stop member 54 from engaging and obstructing fluid flow
into the tubular extension 63.
[0044] FIG. 6 is the cross-sectional elevation view of an
embodiment of the sand fallback tool 10 of FIGS. 4 and 5 after
restoration of power to the submersible pump (not shown) and
resumption of fluid flow upwardly through the sand fallback tool
10. Pressurized fluid is pumped into the distal connector 25 and
displaces the flow stop member 34 from the seat 21 of the distal
check valve 31. Fluid flows upwardly into and through the annular
passage 18 that surrounds the tubular flow divider 14, through the
"S"-curve formed by the distal end 64 of the tubular extension 63
extending into the central passage 16 of the tubular flow divider
14, radially inwardly into the tubular extension 63 and then
through the proximal connector 26 to the production tubing (not
shown) connected thereto. As fluid flows through this tortuous
pathway, the flowing fluid unsettles and disturbs settled sand 57
thereby causing settled sand 57 to become entrained within the
fluid flow. As the amount of the accumulated settled sand 57 atop
the flow stop member 54 of the proximal check valve 51 becomes more
unsettled and disturbed, the fluid pressure on the flow stop member
54 causes it to become displaced from the seat 55 resulting in
fluidization of the column 59 of settled sand 57, which results in
further entrainment of the settled sand 57 in the flow of fluid
through the sand fallback tool 10. The design of the sand fallback
tool 10 enables the removal of the column 59 of settled sand 57
from the central passage 16 of the tubular flow divider 14 within a
relatively short period after restoration of operation of the
submersible pump.
[0045] FIG. 7 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool 10 of the present invention.
The sand fallback tool 10 of FIG. 7 comprises an elongate outer
tubular body 12 having a proximal end 22 with a proximal connector
26 for coupling the sand fallback tool 10 to production tubing (not
shown), a distal end 24 having a distal connector 25 for coupling
to a submersible pump (not shown), and a chamber 11 within the
outer tubular body 12 between the proximal connector 26 and the
distal connector 25. The chamber 11 within the outer tubular body
12 is divided into passages by a tubular flow divider 14 having a
distal end 15, a central passage 16 within the tubular flow divider
14, and a proximal end 17. The tubular flow divider 14 of the sand
fallback tool 10 of FIG. 7 is supported within the chamber 11 of
the outer tubular body 12 centrally about the axis 13 to divide the
portion of the chamber 11 in which the tubular flow divider 14 is
supported into two flow passages through which fluid entering the
distal connector 25 may flow to the proximal connector 26. The two
flow passages include a central passage 16 disposed within the flow
divider 14 and surrounding the axis 13 and the annular passage 18
radially intermediate the tubular flow divider 14 and the outer
tubular body 12.
[0046] The sand fallback tool 10 of FIG. 7 further includes a
distal check valve 31 having a permeable divider 33 disposed within
the chamber 11 of the outer tubular body 12 proximal to the distal
connector 25 and a flow stop member 34 movably captured below the
divider 33. The divider 33 of the distal check valve 31 may include
a plurality of holes or slots through which fluid entering the
chamber 11 through the distal connector 25 flows with the distal
check valve 31 in the open position illustrated in FIG. 7. The
distal check valve 31 of FIG. 7 further includes a seat 21 disposed
within the chamber 11 of the outer tubular body 12, the seat 21
sized for sealed engagement with the flow stop member 34. FIG. 7
illustrates a flow stop member 34 that is spherical in shape, but
in other embodiments of the sand fallback tool 10 of the present
invention, the flow stop member 34 can be an elongate plug with a
tapered nose, a conical shape, or any other shape that can maintain
proper orientation within the cage 30 and sealably engage the seat
21 of the distal check valve 31 to prevent unwanted fluid flow or
sand passage from the distal connector 25 into the submersible pump
(not shown) connected thereto during interruptions of operation of
the submersible pump. The flow stop member 34 may be of a material
for providing to the flow stop member 34 a combination of size,
weight and surface friction to fluid flow upwardly through the
distal connector 25 and then around the flow stop member 34 when
the flow stop member 34 is displaced from the seat 21 and so that
the flow stop member 34 later drops to sealably engage the seat 21
upon termination of operation of the submersible pump (not shown),
only to be again displaced from the seat 21 by fluid pressure and
flow of fluid entering the chamber 11 through the distal connector
25 during resumed operation of the submersible pump.
[0047] The central passage 16 of the tubular flow divider 14 of the
sand fallback tool 10 of FIG. 7 further includes a distal necked
portion 52 that is smaller in size than an adjacent portion 53 of
the central passage 16 that is distal to the distal end 15 of the
tubular flow divider 14. The central passage 16 further includes a
proximal check valve 51 that is proximal to the distal end 15 and a
proximal flow stop member 54 within the central passage 16. The
proximal check valve 51 further includes a seat 55 within the
tubular flow divider 14 at the distal necked portion 52 that is
shaped for sealed engagement with the proximal flow stop member 54.
The proximal flow stop member 54 of the proximal check valve 51
engages the seat 55 to prevent fluid and settled sand from flowing
from the distal end 15 of the central passage 16. The sand fallback
tool 10 of FIG. 7 further includes a permeable divider 58 within
the central passage 16 to limit the movement of the flow stop
member 54 within the central passage 16. The sand fallback tool 10
of FIG. 7 further includes a tubular extension 63 coupled to the
proximal connector 26 of the outer tubular body 12 and extending
distally into the central passage 16. The distal end 64 of the
tubular extension 63 is disposed within the central passage 16. The
tubular extension 63 and the tubular flow divider 16 causes fluid
flowing upwardly within the annular passage 18 to flow through an
"S"-shaped pathway disposed at the proximal end 17 of the flow
passage divider 14. The flow of fluid within the annular passage 18
flows upwardly to the proximal end 17 of the tubular flow divider
14, then passes radially inwardly through the holes 61 adjacent to
the proximal end 17 of the tubular flow divider 14, then fluid
flows downwardly between the tubular extension 63 and the tubular
flow divider 14, then radially inwardly and into the distal end 64
of the tubular extension 63 to mix with fluid flowing from the
central passage 16 (if any), and then upwardly from the sand
fallback tool 10 through the proximal connector 26. The tubular
extension 63 extends the bore of the proximal connector 26
downwardly into the central passage 16. This arrangement
substantially prevents settling sand that may enter the sand
fallback tool 10 through the proximal connector 26 to settle within
the central passage 16 instead of settling within the annular
passage 18, as will be discussed in more detail in connection with
FIG. 8.
[0048] The tubular flow divider 14 of the sand fallback tool 10 of
FIG. 7 further includes a plurality of apertures 56. The apertures
56 allow pressurized fluid to flow from the annular passage 18
through the apertures 56 in the tubular flow divider 14 into the
central passage 16 upon restoration of operation of the submersible
pump, as discussed in connection with FIG. 9 below. The apertures
56 in the tubular flow divider 14 thereby promote fluidization and
unsettling of the column 59 of settled sand 57 accumulated within
the central passage 16 as illustrated in FIG. 8, and may also
provide for the relieving of pressurized pockets of gas that may
remain within the column 59 of settled sand 57 after the sand
fallback tool 10 is removed from a well.
[0049] FIG. 8 is the cross-sectional elevation view of the
embodiment of the sand fallback tool 10 of FIG. 7 after
interruption of the power supply to the submersible pump (not
shown) and after a column 59 of settled sand 57 has settled from
the stagnant fluid in the production tubing (not shown) above the
sand fallback tool 10 through the proximal connector 26, through
the tubular extension 63 and into the central passage 16 of the
sand fallback tool 10. The settled sand 57 is shown in FIG. 8 to
have accumulated into a column 59 of settled sand 57 atop the
seated flow stop member 54 of the proximal check valve 51, which is
shown in FIG. 8 in the closed position. There is an unobstructed
axial settling path 99 from the proximal connection 26 into the
central passage 16 of tubular divider 14 that is supported within
the chamber 11 of the outer tubular body 12. It can be seen in FIG.
8 how the column 59 of settled sand 57 has settled through the
permeable divider 58 that limits movement of the flow stop member
54 and onto the flow stop member 54. The tubular extension 63 of
the embodiment of the sand fallback tool 10 of FIGS. 7-9 does not
contain holes as it does in the embodiment of the sand fallback
tool 10 of FIG. 1-3 because the permeable divider 58 prevents the
flow stop member 54 from engaging and obstructing fluid flow into
the tubular extension 63.
[0050] FIG. 9 is the cross-sectional elevation view of an
embodiment of the sand fallback tool 10 of FIGS. 7 and 8 after
restoration of power to the submersible pump (not shown) and
resumption of fluid flow upwardly through the sand fallback tool
10. Pressurized fluid is pumped into the distal connector 25 and
displaces the flow stop member 34 from the seat 21 of the distal
check valve 31. Fluid flows upwardly into the annular passage 18,
radially inwardly through the holes 61 in the tubular flow divider
14, downwardly between the tubular flow divider 14 and the tubular
extension 63, radially inwardly and then into the distal end 64 of
the tubular extension 63, and fluid exits the sand fallback tool 10
through the proximal connector 26 to the production tubing (not
shown) connected thereto. As fluid flows through this pathway, the
flowing fluid unsettles and disturbs settled sand 57 thereby
causing settled sand 57 to become entrained within the fluid flow.
As the amount of the accumulated column 59 of settled sand 57 atop
the flow stop member 54 of the proximal check valve 51 becomes more
unsettled, the fluid pressure bearing on the flow stop member 54
causes it to become displaced from the seat 55 and fluid begins to
channel and flow through the column 59 of the settled sand 57,
which results in further entrainment of the settled sand 57 in the
flow of fluid through the sand fallback tool 10. In addition,
pressurized fluid within the annular passage 18 flows through
apertures 56 in the tubular flow divider 14 into the central
passage 16 to further fluidize and unsettle the column 59 of
settled sand 57 accumulated within the central passage 16 of the
tubular flow divider 14. The apertures 56 in the tubular flow
divider 14 are large enough to allow fluid flow from the annular
passage 18 into the central passage 16, but small enough for the
tubular flow divider 14 to provide support for accumulation of a
column 59 of settled sand 57 therewithin. It will be understood
that sand, like many other materials, can accumulate within a fluid
with sufficient cohesion to create a column 59 of settled sand 57
within the central passage 16 of the tubular flow divider 14
without sand escaping the central passage 16 through the apertures
56 to enter the annular passage 18.
[0051] FIG. 10 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool 10 of the present invention.
The sand fallback tool 10 of FIG. 10 comprises an elongate outer
tubular body 12 having a proximal end 22 with a proximal connector
26 for coupling the sand fallback tool 10 to production tubing (not
shown), a distal end 24 with a distal connector 25 for coupling to
a submersible pump (not shown), and a chamber 11 within the outer
tubular body 12 therebetween. The chamber 11 within the outer
tubular body 12 is divided into flow passages by a tubular flow
divider 14 having a distal end 15, a central passage 16 within the
tubular flow divider 14, and a proximal end 17. The tubular flow
divider 14 divides the chamber 11 into a central passage 16 within
the tubular flow divider 14 and an annular passage 18 radially
intermediate the tubular flow divider 14 and the outer tubular body
12. Holes 61 in the tubular flow divider 14 adjacent to the
proximal end 17 allow fluid flow from the annular passage 18 to
flow radially inwardly towards the tubular extension 63, then
downwardly between the tubular extension 63 and the proximal end 17
of the tubular flow divider 14, then radially inwardly to mix with
fluid flowing upwardly from the central passage 16, if any, then to
exit the chamber 11 and the apparatus 10 through the tubular
extension 63 and the proximal connector 26. The tubular flow
divider 14 of the sand fallback tool 10 of FIG. 10 is supported
within the chamber 11 of the outer tubular body 12 centrally about
the axis 13 to divide the portion of the chamber 11 in which the
tubular flow divider 14 is supported into two fluid flow passages
through which fluid entering the sand fallback tool 10 through the
distal connector 25 may flow to the proximal connector 26. The
tubular flow divider 14 of the sand fallback tool 10 of FIG. 10
further includes a bypass annulus 19 within the tubular flow
divider 14 and in fluid communication through a plurality of bypass
apertures 41 with the central passage 16 of the tubular flow
divider 14. The bypass apertures 41 allow fluid to flow into the
distal end 15 of the tubular flow divider 14 and to thereby enter
the central passage 16, then to flow through the bypass apertures
41 into the bypass annulus 19, upwardly within the bypass annulus
19 and then from the bypass annulus 19 through the bypass apertures
41 back into the central passage 16. The bypass apertures 41 and
the bypass annulus 19 thereby provide additional agitation,
fluidization, entrainment and removal of a column 59 of settled
sand 57 (not shown in FIG. 10--see FIG. 11) from the central
passage 16 upon resumption of operation of the submersible pump, as
illustrated in FIG. 12. The embodiment of the sand fallback tool 10
of FIGS. 10-12 does not include a proximal check valve as does the
embodiments of FIGS. 1-9.
[0052] FIG. 11 is the cross-sectional elevation view of the
embodiment of the sand fallback tool 10 of FIG. 10 after
interruption of the power supply to the submersible pump (not
shown) and after a column 59 of settled sand 57 has settled from
the stagnant fluid in the production tubing (not shown) above the
sand fallback tool 10 through the proximal connector 26 and into
the central passage 16 of the sand fallback tool 10, then through
the central passage 16 to accumulate atop the cage 30 of the distal
check valve 31 below the tubular flow divider 14 and below the
central passage 16. There is an unobstructed axial settling path 99
from the proximal connection 26 into the central passage 16 of
tubular divider 14 that is supported within the chamber 11 of the
outer tubular body 12. The distal check valve 31 is proximal to the
distal end 24 of the sand fallback tool 10 and includes a cage 30
that limits the range of movement of the flow stop member 34 of the
distal check valve 31. The column 59 of settled sand 57 is shown as
filling portions of the chamber 11 of the outer tubular body 12 of
the sand fallback tool 10 below the distal end 15 of the tubular
flow divider 14 because there is no proximal check valve within the
central passage 16 of the tubular flow divider 14 to prevent
settled sand 57 from passing through the central passage 16. Once
the level of the settled sand 57 rises to the distal end 15 of the
tubular flow divider 14, the column 59 of settled sand 57 then
begins accumulating within the central passage 16 as illustrated in
FIG. 11.
[0053] FIG. 12 is the cross-sectional elevation view of an
embodiment of the sand fallback tool 10 of FIGS. 10 and 11 after
restoration of power to the submersible pump and resumption of
fluid flow upwardly through the sand fallback tool 10. Pressurized
fluid enters the sand fallback tool 10 through the distal connector
25 and, due to fluid pressure and rapid flow, immediately clears
the settled sand 57 from the area of the chamber 11 adjacent to the
holes 32 of the cage 30 of the distal check valve 31, and from
around and atop the cage 30 of the distal check valve 31 that
limits the movement of the flow stop member 34 of the distal check
valve 31. The removed portion of the settled sand 57 is entrained
in and removed by fluid flow moving up the annular passage 18, then
radially inwardly through the holes 61 in the tubular flow divider
14, downwardly between the tubular extension 63 and the tubular
flow divider 14, through the "S"-curve formed by the tubular
extension 63 extending into the proximal end 17 of the tubular flow
divider 14, and from the sand fallback tool 10 through the proximal
connector 26. The remaining portion of the settled sand 57 in the
central passage 16 will then be removed by pressurized fluid
entering the distal end 15 of the tubular flow divider 14 and then
flowing through the bypass apertures 41 into the bypass annulus 19.
Fluid within the bypass annulus 19 will re-enter the central
passage 16 through the bypass apertures 41 at or near the top of
the settled sand 57 to entrain and remove the settled sand 57 from
the central passage 16 until the central passage 16 has been
cleared, and then simultaneous fluid flow through both the central
passage 16 and the annular passage 18 resumes.
[0054] FIG. 13 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool 10 of the present invention.
The embodiment of the sand fallback tool 10 of FIG. 13 comprises an
elongate outer tubular body 12 having a proximal end 22 with a
proximal connector 26 for coupling the sand fallback tool 10 to a
string of production tubing (not shown), a distal end 24 with a
distal connector 25 for coupling to a submersible pump (not shown),
and a chamber 11 within the outer tubular body 12 axially between
the proximal connector 26 and the distal connector 25. The chamber
11 within the outer tubular body 12 is divided into passages by a
tubular flow divider 14 having a distal end 15, a central passage
16 within the tubular flow divider 14, and a proximal end 17. The
tubular flow divider 14 of the sand fallback tool 10 of FIG. 13 is
supported within the chamber 11 of the outer tubular body 12
centrally about the axis 13 to divide a portion of the chamber 11
in which the tubular flow divider 14 is supported into two flow
passages through which fluid entering the distal connector 25 may
flow to the proximal connector 26. The two flow passages include a
central passage 16 disposed within the tubular flow divider 14 and
surrounding the axis 13 and the annular passage 18 radially
intermediate the tubular flow divider 14 and the outer tubular body
12.
[0055] The sand fallback tool 10 of FIG. 13 further includes a
distal check valve 31 having a cage 30 disposed within the chamber
11 of the outer tubular body 12 proximal to the distal connector 25
and a flow stop member 34 movably captured within the cage 30. The
cage 30 of the distal check valve 31 includes a plurality of holes
32 through which fluid entering the chamber 11 through the distal
connector 25 flows with the distal check valve 31 in the open
position illustrated in FIG. 13. The distal check valve 31 of FIG.
13 further includes a seat 21 disposed within the chamber 11 of the
outer tubular body 12, the seat 21 sized for sealed engagement with
the flow stop member 34. FIG. 13 illustrates a flow stop member 34
that is spherical in shape, but in other embodiments of the sand
fallback tool 10 of the present invention, the flow stop member 34
can be an elongate plug with a tapered nose, a conical shape, or
any other shape that can maintain proper orientation and sealably
engage the seat 21 of the distal check valve 31 to prevent unwanted
fluid flow or sand passage into the submersible pump during
interruptions of operation of the submersible pump. The flow stop
member 34 may be of a material for providing to the flow stop
member 34 a combination of weight and friction to fluid flow there
around so that the flow stop member 34 drops within the cage 34 to
sealably engage the seat 21 upon termination of operation of the
submersible pump (not shown) and is displaced from the seat 21 by
fluid pressure and flow of fluid entering the chamber 11 through
the distal connector 25 during operation of the submersible
pump.
[0056] The central passage 16 of the tubular flow divider 14 of the
sand fallback tool 10 of FIG. 13 further includes a distal necked
portion 52 that is smaller in size than an adjacent portion 53 of
the central passage 16 proximal to the distal end 15 of the tubular
flow divider 14. The central passage 16 proximal to the distal end
15 further includes a proximal check valve 51 including the distal
necked portion 52 and a proximal flow stop member 54 within the
central passage 16. The proximal check valve 51 further includes a
seat 55 within the tubular flow divider 14 adjacent to the distal
necked portion 52 that is shaped for sealed engagement with the
proximal flow stop member 54. As with the distal check valve 31,
the proximal flow stop member 54 engages the seat 55 to prevent
fluid and settled sand from flowing from the distal end 15 of the
central passage 16 during interruptions of operation of the
submersible pump (not shown). The sand fallback tool 10 of FIG. 13
further includes a tubular extension 63 coupled to the proximal
connector 26 of the outer tubular body 12 and extending distally
into the proximal end 17 of the tubular flow divider 14. The distal
end 64 of the tubular extension 63 is disposed within the central
passage 16. As with the embodiment of the apparatus 10 illustrated
in FIGS. 1-3, the distal end 64 of the tubular extension 63 serves
to limit the range of upwardly movement of the proximal flow stop
member 54 when the proximal flow stop member 54 is displaced from
the seat 55 by fluid pressure and fluid flow is applied to the
proximal flow stop member 54 by operation of the submersible pump
(not shown) coupled to the distal connector 25 of the sand fallback
tool 10. As with the embodiment of the apparatus 10 illustrated in
FIGS. 1-3, the tubular extension 63 includes holes 65 that continue
to allow fluid to flow into the tubular extension 63 when the flow
stop member 54 engages the distal end 64 of the tubular extension
63. The tubular extension 63 and the tubular flow divider 16 cause
fluid flowing upwardly within the annular passage 18 to flow
through an "S"-shaped pathway disposed at the proximal end 17 of
the flow passage divider 14. The flow of fluid within the annular
passage 18 flows upwardly to the proximal end 17 of the tubular
flow divider 14, then flows radially inwardly towards the tubular
extension 63, then downwardly to the holes 65 within the tubular
extension 63 and then radially inwardly through the holes 65 into
the tubular extension 63 to mix with fluid flowing from the central
passage 16 (if any) and then from the sand fallback tool 10 through
the proximal connector 26. The tubular extension 63 extends the
bore of the proximal connector 26 downwardly into the central
passage 16. This arrangement provides an unobstructed axial
settling path 99 (see FIG. 14) through which settling sand may
settle from the production tubing (not shown) coupled to the
proximal connector 26 during periods of interruption of the power
supply to a submersible pump (now shown) coupled to the distal
connector 25, and this arrangement causes settling sand that may
enter the sand fallback tool 10 through the proximal connector 26
to settle within the central passage 16 instead of settling within
the annular passage 18, as will be discussed in more detail in
connection with FIG. 14. Fluid that does not flow through the full
length of the annular passage 18 passes radially inwardly through
channels 69 to enter the central passage 16, then flows upwardly
through the central passage 16 to the holes 65 of the tubular
extension 63 and there mixes with the fluid flow emerging from the
annular passage 18, then flowing radially inwardly towards the
tubular extension 63, then downwardly between the tubular extension
63 and the proximal end 17 of the tubular flow divider 14 to the
holes 65 (i.e., through the "S"-shaped flow path) to mix with the
fluid flowing through the central passage 16 and exiting the sand
fallback tool 10 through the tubular extension 63 and the proximal
connector 26.
[0057] FIG. 14 is the cross-sectional elevation view of the
embodiment of the sand fallback tool 10 of FIG. 13 after
interruption of the power supply to the submersible pump (not
shown) and after a column 59 of settled sand 57 has settled from
the stagnant column of produced fluid residing in the production
tubing (not shown) above the sand fallback tool 10. As described
above in connection with other embodiments, upon interruption of
the power supply to the submersible pump, the proximal flow stop
member 54 sealably engages the seat 55 of the proximal check valve
51 and the distal flow stop member 34 sealably engages the seat 21
of the distal check valve 31 due to the density of the proximal
flow stop member 54 and the distal flow stop member 34 being
greater than the density of the fluid produced through the sand
fallback tool 10. FIG. 14 shows the settled sand 57 that settles
downwardly through the unobstructed axial settling path 99 from the
production tubing and entering the sand fallback tool 10 through
the proximal connector 26, then through the tubular extension 63
extending downwardly therefrom, and into the central passage 16 to
accumulate atop the proximal flow stop member 54 engaged with the
seat 55 of the proximal check valve 51. FIG. 14 shows that the
annular passage 18 remains open and unobstructed by settled sand
due to the alignment of the central passage 16 with the tubular
extension 63. The holes 65 in the tubular extension 63 are below
the proximal end 17 of the tubular extension 63 to prevent or
minimize unwanted settling sand entry into the annular passage 18.
The sizes of the tubular extension 63 and the central passage 16
into which the tubular extension 63 extends can be selected to
provide a desired pressure drop in the fluid produced up the
annular passage 18 so that there is a pressure differential from
the annular passage 18 into the central passage 16.
[0058] FIG. 15 is the cross-sectional elevation view of an
embodiment of the sand fallback tool 10 of FIGS. 13 and 14 after
restoration of power to the submersible pump (not shown) coupled to
the distal connector 25 of the sand fallback tool 10 and resumption
of fluid flow upwardly through the sand fallback tool 10. Upon
restoration of the operation of the submersible pump, fluid
pressure initially bears against and displaces the flow stop member
34 of the distal check valve 31 from the seat 21 to provide fluid
flow from the submersible pump, through the distal connector 25,
through the holes 32 of the cage 30 of the distal check valve 31,
through the full length of the annular passage 18, then radially
inwardly towards the tubular extension 63, then downwardly between
the tubular extension 63 and the proximal end 17 of the tubular
flow divider 14 to the holes 65 (i.e., through the "S"-curve at the
proximal end 17 of the tubular flow divider 14 to exit from the
sand fallback tool 10 through the proximal connector 26. As flow
through these structures occurs, the turbulence of the flow causes
unsettling and fluidization of at least a top portion of the column
59 of settled sand 57 within the central passage 16. At first,
small amounts of the settled sand begin to leave the column 59 of
settled sand 57 in the central passage 16 and become entrained in
the fluid flow emerging from the annular passage 18 and leaving the
sand fallback tool 10 through the proximal connector 26. As the
column 59 lightens, fluid pressure against the flow stop member 54
of the proximal check valve 51 eventually displaces the flow stop
body 54 from the seat 55 and fluid begins to flow radially inwardly
through the channels 69, into the central passage 16, around the
flow stop member 54 and channeling through the column 59 of settled
sand 57, thereby further fluidizing and entraining sand in the
fluid flow exiting the sand fallback tool 10 at the proximal
connector 26.
[0059] FIG. 16 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool 10 of the present invention.
The embodiment of the sand fallback tool 10 of FIG. 16 comprises an
elongate outer tubular body 12 having a proximal end 22 with a
proximal connector 26 for coupling the sand fallback tool 10 to a
string of production tubing (not shown), a distal end 24 with a
distal connector 25 for coupling to a submersible pump (not shown),
and a chamber 11 within the outer tubular body 12 axially between
the proximal connector 26 and the distal connector 25. The chamber
11 within the outer tubular body 12 is divided into passages by a
tubular flow divider 14 having a distal end 15, a central passage
16 within the tubular flow divider 14, and a proximal end 17. The
tubular flow divider 14 of the sand fallback tool 10 of FIG. 16 is
supported from the distal end 15 within the chamber 11 of the outer
tubular body 12 centrally about the axis 13 to divide the portion
of the chamber 11 in which the tubular flow divider 14 is supported
into two flow passages through which fluid entering the distal
connector 25 may flow to the proximal connector 26. The two flow
passages include a central passage 16 disposed within the flow
divider 14 and surrounding the axis 13 and the annular passage 18
radially intermediate the tubular flow divider 14 and the outer
tubular body 12.
[0060] The sand fallback tool 10 of FIG. 16 further includes a
distal check valve 31 having a cage 30 disposed within the chamber
11 of the outer tubular body 12 proximal to the distal connector 25
and a flow stop member 34 movably captured within the cage 30. The
cage 30 of the distal check valve 31 includes a plurality of holes
32 through which fluid entering the chamber 11 through the distal
connector 25 flows with the distal check valve 31 in the open
position illustrated in FIG. 16. The distal check valve 31 of FIG.
16 further includes a seat 21 disposed within the chamber 11 of the
outer tubular body 12, the seat 21 sized for sealed engagement with
the flow stop member 34. FIG. 16 illustrates a flow stop member 34
that is spherical in shape, but in other embodiments of the sand
fallback tool 10 of the present invention, the flow stop member 34
can be an elongate plug with a tapered nose, a conical shape, or
any other shape that can maintain proper orientation and sealably
engage the seat 21 of the distal check valve 31 to prevent unwanted
fluid flow or sand passage into the submersible pump during
interruptions of operation of the submersible pump. The flow stop
member 34 may be of a material for providing to the flow stop
member 34 a combination of weight and friction to fluid flow there
around so that the flow stop member 34 drops within the cage 30 to
sealably engage the seat 21 upon termination of operation of the
submersible pump (not shown) and is displaced from the seat 21 by
fluid pressure and flow of fluid entering the chamber 11 through
the distal connector 25 during operation of the submersible
pump.
[0061] The central passage 16 of the tubular flow divider 14 of the
sand fallback tool 10 of FIG. 16 further includes a distal necked
portion 52 that is smaller in size than an adjacent portion 53 of
the central passage 16 that is proximal to the distal end 15 of the
tubular flow divider 14. The central passage 16 proximal to the
distal end 15 further includes a proximal check valve 51 including
the distal necked portion 52 and a proximal flow stop member 54
within the central passage 16. The proximal check valve 51 further
includes a seat 55 within the tubular flow divider 14 adjacent to
the distal necked portion 52 that is shaped for sealed engagement
with the proximal flow stop member 54. As with the distal check
valve 31, the proximal flow stop member 54 engages the seat 55 to
prevent fluid and settling sand from flowing from the distal end 15
of the central passage 16 during interruptions of power supply to
the submersible pump coupled to the distal connector 25 of the
apparatus 10. The sand fallback tool 10 of FIG. 16 further includes
a resilient funnel member 75 coupled to the proximal end 17 of the
tubular flow divider 14, the funnel member 75 being shaped as an
upwardly expanding section of a cone to cause fluid and settling
sand entering the outer tubular body 12 through the proximal
connector 26 during periods in which the submersible pump (not
shown) coupled to the distal connector 25 is not in operation to be
guided to and to enter the proximal end 17 of the tubular flow
divider 14 and to thereafter move down the central passage 16
towards the distal end 15. The funnel member 75 is resiliently
deformable and may be made of rubber or some other material that
can be deformed by application of force and then resiliently
restored to its original shape after the forces causing deformation
are removed. The permeable divider 58 within the central passage 16
serves to limit the range of upwardly movement of the proximal flow
stop member 54 when the proximal flow stop member 54 is displaced
from the seat 55 by fluid pressure applied to the proximal flow
stop member 54 by operation of the submersible pump (not shown)
coupled to the distal connector 25 of the sand fallback tool 10.
The flow of fluid entering the sand fallback tool 10 through the
distal connector 25 may flow through both the central passage 16
and the annular passage 18. The flow of fluid within the annular
passage 18 flows upwardly to the proximal end 17 of the tubular
flow divider 14, the fluid pressure collapses and displaces the
funnel member 75 a sufficient amount to allow the fluid flow within
the annular passage 18 to move upwardly beyond the funnel member 75
and to flow radially inwardly to mix with fluid flowing upwardly
from the central passage 16 (if any) before exiting the sand
fallback tool 10 through the proximal connector 26. Fluid not
flowing the full length of the annular passage 18 will flow
upwardly through the central passage 16 within the tubular flow
divider 14. The flow of fluid within the central passage 16 first
flows radially inwardly through channels 69 to enter the central
passage 16 and then upwardly through the central passage 16 to the
proximal connector 26. This arrangement substantially causes
settling sand that may enter the sand fallback tool 10 through the
proximal connector 26 during interruption of the power supply to
the submersible pump (not shown) to settle within the central
passage 16 (instead of settling within the annular passage 18), as
will be discussed in more detail in connection with FIG. 17.
[0062] FIG. 17 is the cross-sectional elevation view of the
embodiment of the sand fallback tool 10 of FIG. 16 after
interruption of the power supply to the submersible pump (not
shown) and after settling sand 57 has settled from the stagnant
column of produced fluid residing in the production tubing (not
shown) above the sand fallback tool 10. As described above, the
proximal flow stop member 54 engages the seat 55 of the proximal
check valve 31 after interruption of the power supply and the
distal flow stop member 34 engages the seat 21 of the distal check
valve 31 due to the density of the proximal flow stop member 54 and
the distal flow stop member 34 being greater than the density of
the fluid produced through the sand fallback tool 10. FIG. 17 shows
the settled sand 57 that settles downwardly from the production
tubing and that enters the sand fallback tool 10 through the
proximal connector 26, then is guided by the funnel member 75
extending upwardly from the proximal end 17 of the tubular flow
divider 14 into the central passage 16 of the tubular flow divider
14 to accumulate atop the proximal flow stop member 54 engaged with
the seat 55 of the proximal check valve 51. The settling sand 57
settles downwardly through the unobstructed axial settling path 99
into the central passage 16 to accumulate as a column 59 of settled
sand 57 atop the seated proximal flow stop member 54. FIG. 17 shows
that the annular passage 18 remains open and unobstructed by
settled sand due to the alignment of the central passage 16 with
the unobstructed axial settling path 99 and with the proximal
connector 26, and due to the funnel member 75 being at its widest
span due to the absence of fluid flow and fluid pressure in the
annular passage 18 that can, when present, deflect the funnel
member 75 radially inwardly as illustrated in FIG. 16.
[0063] FIG. 18 is the cross-sectional elevation view of an
embodiment of the sand fallback tool 10 of FIGS. 16 and 17 after
restoration of power to the submersible pump (not shown) coupled to
the distal connector 25 of the sand fallback tool 10 and resumption
of fluid flow upwardly through the sand fallback tool 10. Upon
restoration of the operation of the submersible pump, fluid
pressure initially bears against and displaces the flow stop member
34 of the distal check valve 31 from the seat 21 to provide fluid
flow from the submersible pump, through the distal connector 25,
through the holes 32 of the cage 30 of the distal check valve 31,
through the full length of the annular passage 18, past the funnel
member 75 (now again collapsed in a deformed state by application
of fluid pressure) to exit from the sand fallback tool 10 through
the proximal connector 26. As flow through these structures occurs,
the turbulence of the flow causes unsettling and fluidization of
the column of settled sand 57 (see FIG. 17) within the central
passage 16. At first, small amounts of the settled sand begin to
leave the settled sand column in the central passage 16 and become
entrained in the fluid flow emerging from the annular passage 18
and leaving the sand fallback tool 10 through the proximal
connector 26. As the column 59 of settled sand 57 lightens, fluid
pressure against the flow stop member 54 of the proximal check
valve 51 displaces the flow stop body 54 from the seat 55 of the
proximal check valve 51 and fluid begins to flow radially inwardly
through the channels 69, into the central passage 16, around the
flow stop member 54 and channels through the column 59 of settled
sand 57, thereby further fluidizing and entraining sand in the
fluid flow exiting the sand fallback tool 10 at the proximal
connector 26.
[0064] FIG. 19 is a cross-sectional elevation view of an alternate
embodiment of the sand fallback tool 10 of the present invention.
The embodiment of the sand fallback tool 10 of FIG. 19 comprises an
elongate outer tubular body 12 having a proximal end 22 with a
proximal connector 26 for coupling the sand fallback tool 10 to a
string of production tubing (not shown), a distal end 24 with a
distal connector 25 for coupling to a submersible pump (not shown),
and a chamber 11 within the outer tubular body 12 axially between
the proximal connector 26 and the distal connector 25. The chamber
11 within the outer tubular body 12 is divided into passages by a
tubular flow divider 14 having a distal end 15, a central passage
16 within the tubular flow divider 14, and a proximal end 17. The
tubular flow divider 14 of the sand fallback tool 10 of FIG. 19 is
supported from the proximal end 17 within the chamber 11 of the
outer tubular body 12 centrally about the axis 13 to divide the
portion of the chamber 11 in which the tubular flow divider 14 is
supported into two flow passages through which fluid entering the
distal connector 25 may flow to the proximal connector 26. The two
flow passages include a central passage 16 disposed within the flow
divider 14 and surrounding the axis 13 and the annular passage 18
radially intermediate the tubular flow divider 14 and the outer
tubular body 12.
[0065] The sand fallback tool 10 of FIG. 19 does not include a
distal check valve. Instead, the embodiment of the sand fallback
tool 10 of FIG. 19 comprises a cage 30 disposed within the chamber
11 of the outer tubular body 12 proximal to the distal connector
25, the cage 30 being designed to promote bridging of sand settling
atop the cage 30, to obstruct the pathway of settling sand to
prevent it from settling through the distal connector 25 and into
the submersible pump (not shown). The cage 30 includes a plurality
of holes 32 through which fluid entering or exiting the chamber 11
through the distal connector 25 flows. While the lack of a distal
check valve (due to the lack of a flow stop member) at the distal
connector 25 allows fluid and sand to flow into the sand fallback
tool 10 through the unobstructed axial settling path 99 that
includes the proximal connector 26, then into and through the
chamber 11 and to exit the sand fallback tool 10 through the distal
connector 25. The settling sand 57 passing through the restriction
to flow caused by the distal necked portion 52 of the central
passage 16 is subject to bridging, as shown in FIG. 20, at the
distal necked portion 52 within the central passage 16 of the
tubular flow divider 14 and also atop the cage 30. While the
tendency of the sand entrained within the fluid to bridge is
influenced by many factors such as, but not limited to, the
velocity of the fluid flow, the amount of sand entrained in the
fluid flow, the grain size of the sand, and the dimensions of the
distal necked portion 52 relative to the diameter of the central
passage 16 thereabove, the bridging of the sand promotes sand
settling and accumulation within the central passage 16 and, after
a column 59 of settled sand 57 accumulates within the central
passage 16, it forces fluid that flows into the sand fallback tool
10 through the proximal connector 26 during interruptions in power
supply to the submersible pump to flow through the "S"-curved flow
pathway formed by the distal end 64 of the tubular extension 63
extending downwardly into the central passage 16 in order to get
through the annular passage 18 to the distal connector 25. This
tortuous pathway causes sand entrained in the fluid that enters the
sand fallback tool 10 through the proximal connector 26 to settle
within the central passage 16 and accumulate in a column 59 of
settled sand 57, as shown in FIG. 20 and discussed below, rather
than to follow the tortuous flow path of the "S"-curve, thereby
leaving the annular passage 18 clear and unobstructed.
[0066] FIG. 20 is the cross-sectional elevation view of the
embodiment of the sand fallback tool 10 of FIG. 19 after
interruption of the power supply to the submersible pump (not
shown) and after settling sand 57 has bridged and then settled from
the stagnant fluid in the production tubing (not shown) above the
sand fallback tool 10 through the proximal connector 26 and into
the central passage 16 of the sand fallback tool 10 to accumulate
in a column 59 therewithin. FIG. 20 shows the settled sand 57 that
first bridges across the distal necked portion 52 and then
continues to settle downwardly from the production tubing (not
shown) and entering the sand fallback tool 10 through the proximal
connector 26, then through the tubular extension 63 extending
downwardly therefrom, and into the central passage 16 to accumulate
therewithin. FIG. 20 shows that the annular passage 18 remains open
and unobstructed by settled sand due to the alignment of the
central passage 16 with the tubular extension 63 and the holes 65
in the tubular extension 63 being below the proximal end 17 of the
tubular extension 63. The sizes of the tubular extension 63 and the
central passage 16 into which the tubular extension 63 extends can
be selected to provide a desired pressure drop in the fluid
produced up the annular passage 18 so that there is a pressure
differential from the annular passage 18 into the central passage
16.
[0067] FIG. 21 is the cross-sectional elevation view of an
embodiment of the sand fallback tool 10 of FIGS. 19 and 20 after
restoration of power to the submersible pump (not shown) coupled to
the distal connector 25 of the sand fallback tool 10 and resumption
of fluid flow upwardly through the sand fallback tool 10. Upon
restoration of the operation of the submersible pump, fluid
pressure initially provides for restoration of fluid flow from the
submersible pump (not shown), through the distal connector 25,
through the holes 32 of the cage 30, through the annular passage
18, radially inwardly through the holes 61 adjacent to the proximal
end 17 and in the tubular flow divider 14, downwardly along the
tubular extension 63, radially inwardly to enter the distal end 64
of the tubular extension 63 and then to exit from the sand fallback
tool 10 through the proximal connector 26. As flow through these
structures occurs, the turbulence of the flow causes unsettling and
fluidization of the column 59 of settled sand 57 (see FIG. 20)
within the central passage 16. At first, small amounts of the
settled sand 57 begin to leave the settled sand 57 column 59 in the
central passage 16 and become entrained in the fluid flow emerging
from the annular passage 18 and leaving the sand fallback tool 10
through the proximal connector 26. As the column lightens, fluid
pressure against the flow stop member 54 of the proximal check
valve 51 displaces the flow stop body 54 from the seat 55 and fluid
begins to channel through the column 59 of settled sand 57 and flow
around the flow stop member 54, thereby further entraining sand in
the fluid flow exiting the sand fallback tool 10 at the proximal
connector 26.
[0068] In embodiments of the sand fallback tool 10 of the present
invention, the introduction of fluids into the chamber 11 through
the distal connector 25 may introduce bubbles upon resumption of
operation of the submersible pump coupled to the distal connector
25. The introduction of bubbles may enhance the agitation,
unsettling and disturbing of an accumulated column 59 of settled
sand 57 and thereby assist in the gradual removal of the
accumulated column 59 of settled sand 57 from the chamber 11 of the
sand fallback tool 10.
[0069] Components of embodiments of the sand fallback tool 10 of
the present invention may vary in size, shape and structure to suit
the application. For example, but not by way of limitation, the
length, diameter and shape of the tubular flow divider 14, the
tubular extension 63 and/or the distal check valve 31 may vary.
Similarly, the number of apertures 56 of the tubular flow divider
14 and/or the apertures 41 providing fluid communication between
the central passage 16 and the bypass annulus 19 may vary in size,
location, number and distribution. Also, the size, shape and number
of holes 61 in the tubular extension 63 and/or the holes 32 of the
cage 30 may vary. The relative dimensions of components of the
embodiments of the sand fallback tool 10 of the present invention
shown in the appended drawings are merely for purposes of
illustration and are not to be taken as limiting of the present
invention. The size, shape and structure of components of
embodiments of the sand fallback tool 10 of the present invention
may be varied to optimize performance, durability, maintenance,
reconditioning, repair and compatibility with standard tubulars and
other tools.
[0070] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, components and/or groups, but do not
preclude the presence or addition of one or more other features,
integers, steps, operations, elements, components, and/or groups
thereof. The terms "preferably," "preferred," "prefer,"
"optionally," "may," and similar terms are used to indicate that an
item, condition or step being referred to is an optional (not
required) feature of the invention.
[0071] The corresponding structures, materials, acts, and
equivalents of all means or steps plus function elements in the
claims below are intended to include any structure, material, or
act for performing the function in combination with other claimed
elements as specifically claimed. The description of the present
invention has been presented for purposes of illustration and
description, but it is not intended to be exhaustive or limited to
the invention in the form disclosed. Many modifications and
variations will be apparent to those of ordinary skill in the art
without departing from the scope and spirit of the invention. The
embodiment was chosen and described in order to best explain the
principles of the invention and the practical application, and to
enable others of ordinary skill in the art to understand the
invention for various embodiments with various modifications as are
suited to the particular use contemplated.
* * * * *