Note: Descriptions are shown in the official language in which they were submitted.
CA 02881498 2015-02-09
TITLE
[0001] A Downhole Pump Flushing System and Method of Use
FIELD OF THE DISCLOSURE
[0002] The present application relates generally to a system and method for
flushing a downhole
pump for the purpose of preventing or removing, in whole or in part,
accumulations of sand and
other detritus materials from the pump.
BACKGROUND
[0003] This section provides background information to facilitate a better
understanding of the
various aspects of the invention. It should be understood that the statements
in this section of this
document are to be read in this light, and not as admissions of prior art.
[0004] During normal operation of a downhole pump within a well it is common
to pump up .a
combination of water, oil, sand, gas and other detritus material such as wax,
salt and hydrates.
The sand and other detritus material are normally held in suspension within
the oil and/or water
as it is pumped. However, in the event that the pump stops, the sand and other
detritus materials
tend to settle within the pump. It is also common for slugs of material to
enter the pump and clog
it. The accumulation within the pump can cause wear on the pump and its
sealing mechanisms,
decrease efficiency of the pump, plug the pump and can ultimately cause the
seizure of the
pump.
[0005] Cleaning or flushing the accumulated sand and detritus material from a
pump can be time
consuming and expensive. It is also very difficult to remove the material from
the internal
workings of the pump. It may be necessary to remove production tubing and the
pump to gain
access to the accumulated material. This can be quite costly both with regards
to man power for
removing and replacing the pump and production tubing and the amount of time
the well is not
in service. Another method of cleaning or flushing the pump requires the use
of a flush-by truck
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to facilitate flushing of the pump. The flush-by truck lifts the pump,
removing the rotor from the
stator or removing the plunger so that clean fluid may be pumped down the
production tubing in
an effort to remove the accumulated materials in the pump. However, this
method is not
particularly effective at removing accumulations from inside the pump. Again,
there is a cost
associated with this method of flushing the pump related to both the cost of
the flush-by truck
and its operation and the loss of production time for the well.
SUMMARY
[0006] There is provided a downhole pump flushing system that has a pump body
defining an
interior cavity and a lifting member positioned within the interior cavity for
facilitating lifting of
wellbore fluid. The pump body has an inlet end, an outlet end and at least one
flushing inlet. The
inlet end of the pump body has a standing check valve that allows fluid to
enter the pump body.
An injection mandrel is provided in circumferentially engaging relation to an
exterior surface of
the pump body and encompasses the at least one flushing inlet. The injection
mandrel has an
injection port fluidly connected to a fluid outlet port. The fluid outlet port
is in fluid
communication with the at least one flushing inlet of the pump body. A first
end of an injection
line is fluidly connected to the injection port of the injection mandrel and a
second end of the
injection line is fluidly connected to a fluid supply. An annular channel is
created between the
pump body and the injection mandrel adjacent to the at least one flushing
inlet. The annular
channel guides fluid from the fluid outlet port of the injection mandrel into
the at least one
flushing inlet on the pump body. A first sealing member and a second sealing
member are
provided in sealing engagement between the pump body and the injection mandrel
such that a
fluid tight seal is created above and below the at least one flushing inlet.
[0007] The at least one flushing inlet may be positioned proximate the inlet
end of the pump
body. By positioning the at least one flushing inlet in this location, the
injection of flushing or
treatment fluid into the pump body through the injection line allows the fluid
to travel the entire
length of the pump body from the inlet end to the outlet end. The at least one
flushing inlet may
also be angled towards the outlet end of the pump body. This can create a
jetting action of
flushing or treatment fluid that can be used to assist in the breaking up of
accumulations of sand
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and other detritus materials. Where two or more flushing inlet are used, the
flushing inlets may
be positioned in parallel spaced relation to each other and perpendicular to a
longitudinal axis of
the pump body.
[0008] An injection check valve may be positioned within the injection line
that permits the flow
of flushing or treatment fluid towards the first end of the injection line.
While the position of the
check valve may be placed anywhere within the injection line, it may be
beneficial for the
injection check valve to be positioned adjacent the first end of the injection
line such that it
allows flow of fluid into the injection port of the injection mandrel. In the
event of a break in the
injection line, the positioning of the injection check valve adjacent the
first end of the injection
line will, in most cases, be able to prevent wellbore fluid from travelling up
the broken injection
line and into the wellbore between the casing and the production tubing. In
addition to, or in the
alternative, a second injection check valve may also be positioned within the
injection port or
fluid outlet port of the injection mandrel which permits the flow of fluid
through the injection
mandrel and into the at least one flushing inlet.
[0009] The pump body may be a pump barrel and the lifting member may be a
plunger. The
plunger is movable within the pump barrel from the inlet end to the outlet end
to create an
upstroke and from the outlet end to the inlet end to create a downstroke. The
plunger has a
traveling check valve that allows fluid to pass through the plunger from the
inlet end of the pump
barrel to the outlet end of the pump barrel. It may also be beneficial to
include an upper check
valve at the outlet end of the pump barrel to prevent fluid from re-entering
the pump barrel after
it has been expelled.
[0010] In a further embodiment, the downhole pump flushing system has a pump
barrel defining
an interior cavity. The pump barrel has an inlet end, an outlet end and at
least one flushing inlet
and the inlet end has a standing valve that allows fluid to enter the pump
barrel. A plunger is
positioned within the interior cavity of the pump barrel for facilitating
lifting of wellbore fluid.
The plunger is movable within the pump barrel from the inlet end to the outlet
end to create an
upstroke and from the outlet end to the inlet end to create a downstroke. The
plunger has a
traveling check valve that allows fluid to pass through the plunger from the
inlet end of the pump
barrel to the outlet end of the pump barrel. An injection mandrel is provided
in circumferentially
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engaging relation to an exterior surface of the pump barrel such that it
encompasses the at least
one flushing inlet. The injection mandrel has an injection port fluidly
connected to a fluid outlet
port. The fluid outlet port is in fluid communication with the at least one
flushing inlet of the
pump barrel. An injection line has a first end and a second end. The first end
of the injection line
is fluidly connected to the injection port of the injection mandrel and the
second end is fluidly
connected to a fluid supply. An annular channel is created between the pump
barrel and the
injection mandrel adjacent to the at least one flushing inlet. The annular
channel guides fluid
from the fluid outlet port of the injection mandrel into the at least one
flushing inlet on the pump
barrel. A first sealing member and a second sealing member is provided in
sealing engagement
between the pump barrel and the injection mandrel such that a fluid tight seal
is created above
and below the at least one flushing inlet.
[0011] The at least one flushing inlet may be positioned proXimate the inlet
end of the pump
barrel above the standing check valve. It is common for sand and other
detritus material to
accumulate at the standing check valve. By positioning the at least one
flushing inlet in this
location, the injection of flushing or treatment fluid into the pump barrel
occurs at the site of
sand and detritus material accumulation, there is no requirement for the fluid
to travel through
the pump barrel or production tubing to interact with the accumulations. The
flushing or
treatment fluid can interact with the sand and detritus material and carry it
upwards through the
pump barrel. The at least one flushing inlet may also be angled towards the
outlet end of the
pump barrel. This can create a jetting action of flushing or treatment fluid
that can be used to
assist in the breaking up of accumulations of sand and other detritus
materials. Where two or
more flushing inlet are used, the flushing inlets may be positioned in
parallel spaced relation to
each other and perpendicular to a longitudinal axis of the pump barrel.
[0012] An injection check valve may be positioned within the injection line
that permits the flow
of flushing or treatment fluid towards the first end of the injection line.
While the position of the
check valve may be placed anywhere within the injection line, it may be
beneficial for the
injection check valve to be positioned adjacent the first end of the injection
line such that it
allows the flow of fluid into the injection port of the injection mandrel. In
the event of a break in
the injection line, the positioning of the injection check valve adjacent the
first end of the
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injection line will, in most cases, be able to prevent wellbore fluid from
travelling up the broken
injection line and into the wellbore between the casing and the production
tubing. In addition to,
or in the alternative, a second injection check valve may also be positioned
within the injection
port or fluid outlet port of the injection mandrel such that fluid is
permitted to flow through the
injection mandrel into the at least one flushing inlet.
[0013] The injection mandrel may have an engagement member that corresponds to
a stop on the
exterior of the pump barrel for positioning of the pump barrel in engagement
with the injection
mandrel. The engagement member on the injection mandrel may be an engagement
shoulder.
[0014] The outlet end of the pump barrel may have an upper check valve that
prevents fluid from
re-entering the pump barrel after it has been expelled.
[0015] In a further embodiment, the downhole pump flushing system has a pump
barrel that
defines an interior cavity. The pump barrel has an inlet end, an outlet end
and at least one
flushing inlet positioned proximate the inlet end of the pump barrel. The
inlet end of the pump
barrel has a standing check valve that allows fluid to enter the pump barrel.
A plunger is
positioned within the interior cavity of the pump barrel for facilitating
lifting of wellbore fluid.
The plunger is movable within the pump barrel from the inlet end to the outlet
end to create an
upstroke and from the outlet end to the inlet end to create a downstroke. The
plunger has a
traveling check valve that allows fluid to pass through the plunger from the
inlet end of the pump
barrel to the outlet end of the pump barrel. An injection mandrel is provided
in circumferentially
engaging relation with an exterior surface of the pump barrel and it
encompasses the at least one
flushing inlet. The injection mandrel has an injection port fluidly connected
to a fluid outlet port.
The fluid outlet port is in fluid communication with the at least one flushing
inlet of the pump
barrel. The injection mandrel also has a first stop corresponding to a second
stop on the exterior
surface of the pump barrel for proper placement of the pump barrel within the
injection mandrel.
An injection line has a first end and a second end. The first end of the
injection line is fluidly
connected to the injection port of the injection mandrel and the second end is
fluidly connected
to a fluid supply. An injection check valve is positioned at the first end of
the injection line such
that fluid is permitted to flow to the injection port of the injection
mandrel. An annular channel is
created between the pump barrel and the injection mandrel adjacent to the at
least one flushing
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inlet. The annular channel guides fluid from the fluid outlet port of the
injection mandrel into the
at least one flushing inlet on the pump barrel. A first sealing member and a
second sealing
member are provided in sealing engagement between the pump barrel and the
injection mandrel
such that a fluid tight seal is created above and below the at least one
flushing inlet.
[0016] The at least one flushing inlet may be angled towards the outlet end of
the pump barrel.
This can create a jetting action of flushing or treatment fluid that can be
used to assist in the
breaking up of accumulations of sand and other detritus materials. Where two
or more flushing
inlet are used, the flushing inlets may be positioned in parallel spaced
relation to each other and
perpendicular to a longitudinal axis of the pump barrel.
[0017] In addition to the injection check valve positioned at the first end of
the injection line, a
second injection check valve may be positioned within the injection port or
fluid outlet port of
the injection mandrel such that fluid is permitted to flow through the
injection mandrel into the at
least one flushing inlet.
[0018] The outlet end of the pump barrel may have an upper check valve that
prevents fluid from
re-entering the pump barrel after it has been expelled.
[0019] There is further provided a method of flushing a downhole pump. The
method includes
the step of providing a pump. The pump has a pump body defining an interior
cavity. The pump
body has an inlet end, an outlet end and at least one flushing inlet. A
lifting member is positioned
within the interior cavity of the pump body for facilitating lifting of
wellbore fluid. An injection
mandrel is provided in circumferentially engaging relation to an exterior
surface of the pump
body such that it encompasses the at least one flushing inlet. The injection
mandrel has an
injection port fluidly connected to a fluid outlet port. The fluid outlet port
is in fluid
communication with the at least one flushing inlet of the pump body. An
injection line has a first
end and a second end. The first end of the injection line is fluidly connected
to the injection port
of the injection mandrel and the second end is fluidly connected to a fluid
supply. An annular
channel is created between the pump body and the injection mandrel adjacent to
the at least one
flushing inlet. The annular channel guides fluid from the fluid outlet port of
the injection mandrel
into the at least one flushing inlet on the pump body. A first sealing member
and a second
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sealing member are provided in sealing engagement between the pump body and
the injection
mandrel such that a fluid tight seal is created above and below the at least
one flushing inlet. An
injection pump is provided for pumping fluids from the fluid supply through
the injection line.
Fluid agents are then injected into the second end of the injection line such
that the fluid travels
through the injection line and injection mandrel directly into the pump body
through the at least
one flushing inlet.
[0020] The at least one flushing inlet may be positioned proximate the inlet
end of the pump
body which allows the fluid agent to be injected directly into the pump body
proximate to the
inlet end. By positioning the at least one flushing inlet in this location,
the injection of flushing
or treatment fluid into the pump body through the injection line allows the
fluid to travel the
entire length of the pump body from thc. inlet end to the outlet end.
[0021] The injection of fluid agent may occur continuously, on a predetermined
schedule or may
occur at any time chosen by a well site operator. The injection or fluid agent
may also occur after
seizure of the lifting member within the pump body.
[0022] The method may also include addition steps. A controller and battery
back-up may be
provided. The controller and battery back-up are connected to the injection
pump and the
controller is capable of providing on and off signals to the injection pump. A
signal can be sent
from the controller to the injection pump to turn on utilizing power from the
battery back-up in
the event of a power failure. Fluid can then be injected into the second end
of the injection line
such that it travels through the injection line and injection mandrel directly
into the pump body
through the at least one flushing inlet. These steps are beneficial in the
event of a power outage.
When a downhole pump stops moving, sand and other detritus material often fall
out of
suspension and accumulate more quickly than when the pump is operating. By
automatically
starting the injection pump in the event of a power failure, fluid may be
pumped directly into the
pump to maintain the sand and detritus material in suspension. The fluid may
also be used to
flush the wellbore fluid upwards through the pump body to prevent accumulation
of sand and
detritus material.
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[0023] Different types of flushing agents may be used based upon the type of
detritus material
that accumulates in the pump body and the type of treatment required. The use
of a liquid
flushing agent or a foam may be beneficial in flushing the pump body.
[0024] In a further embodiment, a method of flushing a downhole pump includes
the step of
providing a pump having a pump barrel and a plunger movable within the pump
barrel. The
pump barrel defines an interior cavity and has an inlet end, an outlet end and
at least one flushing
inlet positioned proximate the inlet end of the pump barrel. The inlet end of
the pump barrel has
a standing check valve that allows fluid to enter the pump barrel. The plunger
is positioned
within the interior cavity of the pump barrel for facilitating lifting of
wellbore fluid. The plunger
is movable within the pump barrel from the inlet end to the outlet end to
create an upstroke and
from the outlet end to the inlet end to create a downstroke. The plunger has a
traveling check
valve that allows fluid to pass through it from the inlet end of the pump
barrel to the outlet end of
the pump barrel. An injection mandrel is provided in circumferentially
engaging relation with an
exterior surface of the pump barrel such that it encompasses the at least one
flushing inlet. The
injection mandrel has an injection port fluidly connected to a fluid outlet
port. The fluid outlet
port is in fluid communication with the at least one flushing inlet of the
pump barrel. The
injection mandrel has a first stop corresponding to a second stop positioned
on the exterior of the
pump barrel for proper placement of the pump barrel within the injection
mandrel. An injection
line has a first end and a second end. The first end of the injection line is
fluidly connected to the
injection port of the injection mandrel and the second end is fluidly
connected to a fluid supply.
An injection check valve is positioned at the first end of the injection line
such that fluid is
permitted to flow to the injection port of the injection mandrel. An annular
channel is created
between the pump barrel and the injection mandrel adjacent to the at least one
flushing inlet. The
annular channel guides fluid from the fluid outlet port of the injection
mandrel into the at least
one flushing inlet on the pump barrel. A first sealing member and a second
sealing member are
provided in sealing engagement between the pump barrel and the injection
mandrel such that a
fluid tight seal is created above and below the at least one flushing inlet.
An injection pump is
provided for pumping fluids from the fluid supply through the injection line.
Fluid agents are
then injected into the second end of the injection line such that the fluid
travels through the
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injection line and injection mandrel directly into the pump barrel through the
at least one
flushing inlet.
[0025] The injection of fluid agent may occur continuously, on a predetermined
schedule or may
occur at any time chosen by a well site operator. The injection of fluid agent
may also occur after
seizure of the plunger within the pump barrel.
[0026] The method may also include addition steps. A controller and battery
back-up may be
provided. The controller and battery back-up are connected to the injection
pump and the
controller is capable of providing on and off signals to the injection pump. A
signal can be sent
from the controller to the injection pump to turn on utilizing power from the
battery back-up in
the event of a power failure. Fluid can then be injected into the second end
of the injection line
such that it travels through the injection line and injection mandrel directly
into the pump barrel
through the at least one flushing inlet. These steps are beneficial in the
event of a power outage.
When a downhole pump stops moving, sand and other detritus material often fall
out of
suspension and accumulate more quickly than when the pump is operating. By
automatically
starting the injection pump in the event of a power failure, fluid may be
pumped directly into the
pump to maintain the sand and detritus material in suspension. The fluid may
also be used to
flush the wellbore fluid upwards through the pump body to prevent accumulation
of sand and
detritus material.
[0027] Different types of flushing agents may be used based upon the type of
detritus material
that accumulates in the pump body and the type of treatment required. The use
of a liquid
flushing agent or a foam may be beneficial in flushing the pump body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] These and other features will become more apparent from the following
description in
which references are made to the following drawings, in which numerical
references denote like
parts. The drawings are for the purpose of illustration only and are not
intended to in any way
limit the scope of the invention to the particular embodiments shown.
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[0029] FIG. 1 is a schematic representation of a typical well site with the
downhole pump
flushing system installed.
[0030] FIG. 2 is a side elevation view, partially in section, of a downhole
pump flushing system.
[0031] FIG. 3 is an enlarged side elevation view, partially in section, of the
downhole pump
flushing system shown in FIG. 2.
[0032] FIG. 4 is a side elevation view, partially in section, of the downhole
pump flushing
system.
[0033] FIG. 5 is a side elevation view, in section, of the downhole pump
flushing system.
[0034] FIG. 6 is a side elevation view, partially in section, of production
tubing and an injection
mandrel deployed downhole.
[0035] FIG. 7 is a side elevation view, partially in section, of the pump body
being deployed
downhole.
[0036] FIG. 8 is an enlarged side elevation view, partially in section, of the
injection mandrel
and inlet end of the pump barrel with oversized sealing members.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
General Overview of the Downhole Pump Flushing System:
[0037] A general overview of the downhole pump flushing system, generally
identified by
reference numeral 10, as used at a typical well site will now be described
with reference to FIG.
1.
[0038] Referring to FIG. 1, at a typical well site, there is at least one
wellbore 12. As a part of
completion, wellbore 12 has a casing 14 made of cement and perforations, not
shown, are made
in casing 14 using a perforation gun or directional explosions to allow
wellbore fluids to flow
into casing 14. The downhole pump 16, production tubing 18, injection mandrel
20 and injection
line 22, such as capillary tubing, are run down into casing 14 and production
tubing 18 is
anchored in place by anchors 24 or other conventional means. It will be
understood by a person
skilled in the art that anchors 24 may be positioned in various locations or
may not be required.
The positioning of anchors 24, or the decision not to use them, should be
based upon current
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practices in downhole pumping. Downhole pump 16 may be any type of pump known
by a
person skilled in the art for use in downhole operations and may include, but
is not limited to,
plunger pumps, progressive cavity pumps and electric submersible pumps.
[0039] A production tank, not shown, is often provided for storage of the
wellbore fluid that is
produced from wellbore 12. In addition to the production tank, or in the
alternative, a pipe line,
not shown, for delivering the produced wellbore fluid to a treatment facility
or to customer's may
also be present. A blow out preventer 26 may also be included on the wellbore
12. A pump jack
28 is commonly provided for creating lift when using downhole pump 16. Power
to pump jack
28 is supplied by conventional means.
[0040] The flushing fluid is often stored in supply tanks 52 and multiple
fluid supply tanks may
be provided to allow for treatment of pump 16 using different types of
flushing or treatment
fluids. While fluid supply 52 may be stored on site, it is also a possibility
that a truck may
transport flushing or treatment fluid to the well site as needed. An injection
pump 58 is provided
which allows fluid to be pumped from fluid supply 52 down through injection
line 22 to
downhole pump 16. Injection pump 58 can be set up so that it can draw from
different fluid
supplies using a controller and appropriate sensors, not shown, or pump 16 may
be manually
connected to specific fluid supplies 52 as needed. A person of skill will
understand what types of
controllers and sensors are best suited for each wellbore. The pumping of
flushing and treatment
fluids into downhole pump 16 may be completed by either automated or manual
means.
[0041] Downhole pump 16 is made up of a pump body 30 and a lifting member, not
shown,
positioned within an interior cavity, not shown, of pump body 30 for
facilitating lifting of
wellbore fluid. The lifting member is attached to a polished rod 32 which is
connected to pump
jack 28. Pump body 30 has an inlet end 36, an outlet end 38 and at least one
flushing inlet 40.
Injection mandrel 20 is positioned in circumferentially engaging relation to
an exterior surface of
pump body 30 and encompasses flushing inlets 40 on pump body 30. Injection
mandrel 20 has
an injection port 44 fluidly connected to a fluid outlet port 46. Fluid outlet
port 46 is in fluid
communication with flushing inlets 40 of pump body 30. Injection line 22 has a
first end 48 and
a second end 50. First end 48 of injection line 22 is fluidly connected to
injection port 44 of
injection mandrel 20 and second end 50 is fluidly connected to fluid supply
52. A person of skill
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will understand what types of fluid agents can be used. An annular channel,
not shown, is created
between pump body 30 and injection mandrel 20 adjacent to flushing inlet 40.
Annular channel
guides fluid from fluid outlet port 46 of injection mandrel 20 into flushing
inlet 40 on pump body
30. A first sealing member 54 and a second sealing member 56 are provided in
sealing
engagement between pump body 30 and injection mandrel 20 such that a fluid
tight seal is
created above and below flushing inlets 40.
[0042] While it will be understood that flushing inlets 40 may be positioned
anywhere on pump
body 30, in the embodiment shown, flushing inlets 40 are positioned proximate
inlet end 36 of
pump body 30. This allows for flushing or treatment fluid to be injected near
inlet end 36 of
pump body 30 and continue upwards to allow for treatment or flushing of
substantially the entire
pump body 30.
[0043] It will be understood by a person skilled in the art that different
well site set ups will be
required based upon the type of downhole pump used, the type of wellbore fluid
being pumped
and the method in which the wellbore fluid is produced.
[0044] During a treatment or flushing procedure, injection pump 58 is turned
on either manually
by well site operators or by a controller, not shown, which automates the
procedure. Many
controllers are available which could be programmed for this purpose. When a
controller is used,
a schedule can be created by well site personnel based upon well site
procedure or specific
requirements of individual wellbores 12. This can include utilizing different
types of fluid agents
at different intervals or creating a specific schedule for fluid injection.
The controller can also
cause injection pump 58 to inject fluids after seizure of downhole pump 16.
Injection pump 58
pumps flushing or treatment fluid such as a liquid or a foam from fluid supply
52 through
injection line 22 and injection mandrel 20 directly into downhole pump 16
through flushing
inlets 40. When pump 16 is seized, the fluid agent can be continually pumped
down into pump
16 until the accumulation of sand or other detritus material has been cleared.
The fluid agent will
carry away the accumulated material as it travels through flushing inlets 40
and continues
through downhole pump 16 and up production tubing 18. Once sufficient
accumulation has been
removed, downhole pump 16 will be able to be run again and production of the
well 12 can
continue. In the event downhole pump 16 becomes gas locked, injection of
fluids directly into
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pump 16 can help work pump 16 through the gas lock and restore pump 16 to its
normal
operating condition. In addition to batch injection of fluids into downhole
pump 16, injection
pump 58 may be run on a continuous basis to continuously pump fluid from fluid
supply 52
through injection line 22 and injection mandrel 20 directly into downhole pump
16. The amount
of fluid being continually pumped through injection line 22 into downhole pump
16 may be
determined by well site personnel and include anywhere from 0 liters per day
to 500 liters per
day to 20 barrels per day. In some cases, it may be beneficial to use only a
small amount of fluid,
such as 2 liters per day of production fluid or other lubricating fluid, to
help keep pump 16 well
lubricated. In other cases, large quantities of fluid may be pumped through
injection line 22 into
downhole pump 16 to help prevent potential issues related to gas lock or
pumping off. The
determination of the best plan for injection of fluid will be based upon the
individual well 12. In
pumps 16 that are prone to gas lock or pumping off, continuous injection of
fluid may be
beneficial. In wells 12 where pump 16 is prone to pumping up slugs of sand,
batch injection of
fluids may be beneficial. The amount of fluid injected into pump 16 and the
plan for a well 12
can be determined based upon user preference.
[0045] When a controller, not shown, is used, it can be set up to use power
from a battery back-
up, not shown, for turning injection pump 58 on in the event of a power
failure. A person of skill
will understand that a battery back-up is defined as any device known in the
art capable of
providing electrical power to injection pump 58 during a loss of power to pump
jack 28. When
pump jack 28 stops due to a loss of power, fluids within downhole pump 16
cannot be pumped
out. This often results in sand and other detritus material settling out of
the fluid and
accumulating within downhole pump 16. In order to prevent this accumulation
and the
potentially damaging effects, injection pump 58 may be turned on utilizing
power from the
battery back-up and can pump fluids down injection line 22 and into pump 16.
The type of fluid
agent injected can include clean flushing fluid that can push the wellbore
fluid upwards out of
pump 16. The fluid agent may also be a treatment fluid used to help keep the
sand and other
detritus materials in suspension within the wellbore fluid or to dissolve
accumulations and return
them to suspension within the wellbore fluid.
Preferred Embodiment of the Downhole Pump Flushing System:
13
CA 02881498 2015-02-09
[0046] A preferred embodiment of the downhole pump flushing system, generally
identified by
reference numeral 100, will now be described with reference to FIG. 2 through
FIG. 5 and FIG.
8.
[0047] Referring to FIG. 5, the downhole pump flushing system 100 has a pump
barrel 102
defining an interior cavity 104 and a plunger 106 positioned within interior
cavity 104 of pump
barrel 102 for facilitating lifting of wellbore fluid. Referring to FIG. 2,
pump barrel 102 has an
inlet end 108, an outlet end 110 and flushing inlets 112. Inlet end 108 has a
standing check valve
114 that allows fluid to enter pump barrel 102. Referring to FIG. 5, plunger
106 is movable
within pump barrel 102 from inlet end 108 to outlet end 110 to create an
upstroke and from
outlet end 110 to inlet end 108 to create a downstroke. Plunger 106 has a
traveling check valve
116 that allows fluid to pass through plunger 106 from inlet end 108 of pump
barrel 102 to outlet
end 110 of pump barrel 102. Referring to FIG. 2, outlet end 110 of pump barrel
102 has an upper
check valve 118 that prevents the re-entry of fluid into pump barrel 102 after
it has been
expelled. A person of skill will understand that upper check valve 118 is not
required for
downhole pump flushing system 100 to work, however upper check valve 118
improves
efficiency of downhole pump since plunger 106, shown in FIG. 5, does not have
to continuously
pump previously pumped fluids that re-enter pump barrel 102 during downstroke.
[0048] Referring to FIG. 5, flushing inlets 112 are positioned proximate inlet
end 108 of pump
barrel 102 above standing check valve 114 and are in parallel spaced relation
with each other and
perpendicular to a longitudinal axis 120 of pump barrel 102. By positioning
flushing inlets 112 at
inlet end 108 of pump barrel 102, fluid can be directed to the location in
pump barrel 102 most
likely to have accumulations of sand or other detritus material. In addition,
fluid injected into
pump barrel 102 will travel the entire length of pump barrel 102 from inlet
end 108 to outlet end
110, allowing for substantially the entire pump barrel 102 to be treated by
fluid injected through
flushing inlets 112. However, it will be understood by a person skilled in the
art that flushing
inlets 112 may be positioned in different locations on pump barrel 102. The
number of flushing
inlets 112, their size and their locations on pump barrel 102 may be
customized depending upon
the downhole environment, the required injection rates and user preference.
Referring to FIG. 5,
flushing inlets 112 are angled upwards towards outlet end 110 of pump barrel
102. This creates a
14
CA 02881498 2015-02-09
jetting action which may be beneficial in breaking up any accumulations of
sand or other detritus
material that may clog up and ultimately seize plunger 106 within pump barrel
102.
[0049] Referring to FIG. 3 and FIG. 4, an injection mandrel 20 is provided in
circumferentially
engaging relation to an exterior surface 124 of pump barrel 102 and
encompasses flushing inlets
112. Injection mandrel 20 has an engagement member 126 that corresponds to a
stop 128
positioned on exterior surface 124 of pump barrel 102 for properly positioning
pump barrel 102
within injection mandrel 20. A person of skill will understand that stop 128
may be positioned
elsewhere on pump barrel 102 and that it may be used in conjunction with
different completion
components that have corresponding engagement members. For example, while not
shown, stop
128 could be positioned near outlet end 110 of pump barrel 102 to engage an
engagement
member on a pump seat nipple 146, shown in FIG. 5. In the embodiment shown,
engagement
member 126 is an engagement shoulder, however it will be understood by a
person skilled in the
art that different types of engagement members 126 may be used. Injection
mandrel 20 has an
injection port 44 fluidly connected to a fluid outlet port 46. Fluid outlet
port 46 is in fluid
communication with flushing inlets 112 of pump barrel 102. An injection line
22 has a first end
48 and a second end 50, shown in FIG. 1. First end 48 of injection line 22 is
fluidly connected to
injection port 44 of injection mandrel 20. Second end 50 of injection line 22
is fluidly connected
to fluid supply 52, shown in FIG. 1. A first sealing member 134 is positioned
above flushing
inlets 112 in sealing engagement between pump barrel 102 and injection mandrel
20. A second
sealing member 136 is provided below the flushing inlets 112 in sealing
engagement between
pump barrel 102 and injection mandrel 20. This creates a fluid tight seal
around flushing inlets
112 and causes the fluids injected through injection line 22 and injection
mandrel 20 to be guided
into the flushing inlets 112. The positioning of first sealing member 134 and
second sealing
member 136 may be altered to allow for a greater or smaller distance between
them. It is
important to note that first sealing member 134 and second sealing member 136
are not required
to be equidistant from flushing inlets 112. Referring to FIG. 2 through FIG.
4, it can be seen that
three first sealing members 134 and three second sealing member 136 are used
to create the fluid
tight seal. Providing additional sealing members 134 and 136 creates a
redundancy that helps to
prevent leakage of fluid that is injected from the injection line 22 into the
wellbore. Referring to
FIG. 5, two of each of sealing members 134 and 136 are used to create a fluid
tight seal.
CA 02881498 2015-02-09
[0050] A person of skill will understand that in order for injection mandrel
20 to be positioned in
circumferentially engaging relation to pump barrel 102, there must be a
minimum clearance that
allows for placement of pump barrel 102 into position within injection mandrel
20. In addition to
the minimum clearance required for fitting pump barrel 102 within injection
mandrel 20, a
channel 130 should be created around and adjacent flushing inlets 112. Channel
130 guides fluid
from fluid outlet port 46 of injection mandrel 20 into fluid inlets 112.
Channel 130 allows for
greater injection rates since there is a greater area through which the fluid
exiting the fluid outlet
port 46 can enter. It may also provide more uniform injection into interior
cavity 104 as the fluid
has more space to flow around pump barrel 102 and into the flushing inlets
112. If only the
minimum clearance required for fitting pump barrel 102 within injection
mandrel 20 is used, the
amount of pressure that would be required to obtain acceptable injection rates
would be extreme
and in most cases it would be impossible to obtain an acceptable injection
rate due to the small
space through which the flushing fluid would be forced to flow from fluid
outlet port 46 to
flushing inlets 112. Referring to FIG. 3, channel 130 may be obtained by
creating an injection
mandrel port cut out 140 in injection mandrel 20. Injection mandrel port cut
out 140 is a notch
machined out of injection mandrel 20 to create channel 130 around flushing
inlets 112. Referring
to FIG. 4, the additional clearance may also be obtained by creating a pump
injection port cut
out 142 in the pump barrel 102. Pump injection port cut out 142 is a narrowing
of pump barrel
102 in the area of flushing inlets 112 to create channel 130 around flushing
inlets 112. Referring
to FIG. 8, the use of oversized first sealing members 134 and second sealing
members 136 to
allow for increased space between injection mandrel 22 and pump barrel 102 may
also be used to
create channel 130.
[0051] Referring to FIG. 5, an injection check valve 144 is provided to
prevent wellbore fluid
from traveling upwards through injection line 22. It will be understood by a
person skilled in the
art that as long as flushing or treatment fluid remains in injection line 22,
it is unlikely that
wellbore fluid would be able to enter it. However, injection line leakages
could provide the
opportunity for wellbore fluid to travel upwards as injection line 22 leaks
out the flushing or
treatment fluid that normally flows through it. Injection check valve 144 can
be positioned in
many different places, however the purpose remains the same. Injection check
valve 144 permits
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CA 02881498 2015-02-09
fluid to flow towards injection port 44 of injection mandrel 20 while
preventing back flow of
fluid. Damage occurring below injection check valve 144 may allow wellbore
fluid to travel
from interior cavity 104 of pump barrel 102, through injection mandrel 20, up
into injection line
22 and out into wellbore 12 between casing 14 and production tubing 18. By
placing injection
check valve 144 adjacent first end 48 of injection line 22, it becomes less
likely that a breakage
will occur below injection check valve 144. In addition to injection check
valve 144 positioned
within injection line 22, or in the alternative, a second injection check
valve, not shown, may be
positioned within injection port 44 or fluid outlet port 46 of the injection
mandrel 20 such that it
permits fluid to flow through injection mandrel 20 into flushing inlets 112.
[0052] Referring to FIG. 5, a pump seat nipple 146 with sealing members 148 is
included within
the production tubing 18 to help prevent sand and detritus material from
accumulating in the
space between pump barrel 102 and production tubing 18. A person of skill will
understand that
additional completion components may be included within production tubing 18
as required by
downhole conditions and well site personnel.
Installation of the Downhole Pump Eushing System:
[0053] The installation of the downhole pump flushing system 100 into a
wellbore 12 will be
described, with reference to FIG. 5 through FIG. 7. It will be understood by a
person skilled in
the art that various steps will be applicable to the installation of the
system as associated with
other types of pumps such as progressive cavity pumps or electric submersible
pumps. It will be
understood by persons skilled in the art that different methods or techniques
used during the
installation process may also be used.
[0054] Referring to FIG. 6, injection mandrel 20 is run into wellbore 12 with
production tubing
18. Injection port 44 of injection mandrel 20 is connected to first end 48 of
injection line 22. The
diameter of injection line 22 that is used will be determined by several
different factors including
the casing diameter, production tubing diameter and the preferred injection
rate. The smaller the
diameter of injection line 22, the lower the injection rate will be. Injection
line 22 is run into
wellbore 12 in conjunction with injection mandrel 20 and production tubing 18.
Once injection
mandrel 20 is in the proper location, production tubing and/or injection
mandrel can be anchored
17
CA 02881498 2015-02-09
in place using anchors 24, shown in FIG. 1, or other conventional methods. The
positioning of
injection mandrel 20 is based upon the preferred location of the pump and
should, therefore, be
positioned accordingly. A person of skill will be able to determine an
appropriate location for the
pump based upon their knowledge and the specific requirements of each wellbore
12. In an
attempt to avoid large quantities of sand, it is common practice to position
the pump further
uphole then what would be considered an "ideal" location for the pump. Because
this system is
capable of flushing the interior cavity 104 of accumulations of sand and other
detritus material, it
may be possible to position the pump barrel 102 further downhole closer to the
"ideal" position.
Referring to FIG. 5, in the embodiments of the system described, injection
mandrel 20 should be
positioned at a location downhole that allows the user to position inlet end
108 of the pump
barrel 102 in the preferred location for the particular wellbore 12. A person
of skill will
understand that the location of inlet end 108 of pump barrel 102 will be
different for each
wellbore 12 based upon the downhole environment and other factors. After
positioning of
injection mandrel 20, second end 50, shown in FIG. 1, of injection line 22 is
connected to a
nitrogen supply and nitrogen is pumped down injection line 22 to check for
damage to injection
line 22 caused during deployment. Nitrogen is used as it is an inert gas,
however, it will be
understood by a person skilled in the art that other fluids could also be used
for this purpose.
Injection check valve 144, which is located at first end 48 of injection line
22 or within injection
port 44 or fluid outlet port 46 of injection mandrel 20, may be designed to
open only under
predetermined pressures. For example, injection check valve 144 may be
designed to open when
the pressure at injection check valve 144 is 500 psi. Successful opening of
injection check valve
144 using nitrogen under pressure is an indication that injection line 22 is
undamaged. At this
point, the next step may be taken. However, if there appears to be damage to
injection line 22, it
will be necessary to remove production tubing 18, injection mandrel 20 and
injection line 22 and
redeploy with an undamaged injection line 22.
[0055] Once injection mandrel is set 20, production tubing 18 is flushed with
two times its
capacity to remove any sand or detritus material that may be present.
Referring to FIG. 7, after
flushing of production tubing 18, pump barrel 102 is run down into production
tubing 18 towards
injection mandrel 20. Pump barrel 102 is set on injection mandrel 20 and is
then pulled upwards
so that first sealing member 134 is above injection mandrel 20 but second
sealing member 136
18
CA 02881498 2015-02-09
stays below fluid outlet port 46 of injection mandrel 20. First sealing member
134 seals below
fluid outlet port 46 to prevent fluid from flowing downhole. With second
sealing member 136
above injection mandrel 20, fluid pumped down injection line 22 begins to fill
production tubing
18 upwards. This provides a further mechanism to help to ensure that
production tubing 18 is
clean prior to the setting of pump barrel 102. Any sand or detritus material
left within production
tubing 18 after the setting of pump barrel 102 can cause early wearing or
damage. This step also
provides the opportunity to test and calculate injection rates since the
volume of fluid required to
fill production tubing 18 is known or may be easily calculated using the
diameter and length of
tubing 18. Referring to FIG. 5, while injection through injection line 22
continues, pump barrel
102 is dropped into place. First stop 126 on injection mandrel 20 and second
stop 128 on pump
barrel 102 provide means for properly seating pump barrel 102 in injection
mandrel 20 and
prevent damage to injection mandrel 20 caused by excess force when pump barrel
102 is pushed
into position. Once pump barrel 102 has been seated in injection mandrel 20, a
measureable
pressure change should occurs that indicates that pump barrel 102 has been
placed properly. The
fluid being pumped down injection line 22 should now be flowing into interior
cavity 104 of
pump barrel 102. The injection rates can be further tested at this time. Once
pump barrel 102 is
set in injection mandrel 20, additional fluid is pumped down production tubing
18 to completely
fill production tubing 18. Plunger 106 is then manually stroked up and down
several times to
ensure that everything is working properly. Manually stroking plunger 106 will
cause an increase
in pressure within the pump. When everything is determined to be in working
order, the pump is
ready for use. Fluid can then be pumped down injection line 22 to continue
pressuring up the
pump prior to use.
[0056] Any use herein of any terms describing an interaction between elements
is not meant to
limit the interaction to direct interaction between the subject elements, and
may also include
indirect interaction between the elements such as through secondary or
intermediary structure
unless specifically stated otherwise.
[0057] In this patent document, the word "comprising" is used in its non-
limiting sense to mean
that items following the word are included, but items not specifically
mentioned are not
excluded. A reference to an element by the indefinite article "a" does not
exclude the possibility
19
CA 02881498 2015-02-09
that more than one of the element is present, unless the context clearly
requires that there be one
and only one of the elements.
[0058] It will be apparent that changes may be made to the illustrative
embodiments, while
falling within the scope of the invention. As such, the scope of the following
claims should not
be limited by the preferred embodiments set forth in the examples and drawings
described above,
but should be given the broadest interpretation consistent with the
description as a whole.
