Note: Descriptions are shown in the official language in which they were submitted.
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PLUNGER IMPACT SENSOR
TECHNICAL FIELD
[0001] This relates to an impact sensor for use with a plunger in a
hydrocarbon well.
BACKGROUND
[0002] In hydrocarbon producing wells, it is generally necessary to
assist the fluids to
reach the surface. In some wells, primarily gas producing wells (i.e. wells in
formations that
produce a high concentration of gas-phase hydrocarbons), one system used to
assist
production involves the use of a plunger, which acts as a piston to lift
accumulated liquids.
The plunger is moved upward by gas pressure below the plunger. As a result of
factors such
as variation in pressure accumulated and the weight of the liquid above the
plunger, the
plunger may return to the surface at different speeds, some of which may be
damaging to the
equipment and may be unsafe. U.S. patent no. 7,337,854 (Horn et al.) entitled
"Gas-
pressurized lubricator and method" discusses one design that attempts to
reduce the kinetic
energy of a plunger, while U.S. patent no. 7,219,725 (Chisolm) entitled
"Instrumented
plunger for an oil or gas well" describes sensor assemblies for measuring the
velocity of a
plunger.
SUMMARY
[0003] According to an aspect, there is provided a lubricator assembly,
comprising a
lubricator body having a bottom end in communication with a well, a top end,
and one or
more production flow ports, a spring within the lubricator body and above the
one or more
production flow ports, the spring having a movable end and a fixed end above
the movable
end, the spring being compressible in a longitudinal direction, the spring
compressing in
response to a plunger return force, a switch above the movable end of the
spring, the switch
generating a signal when actuated, and an actuator carried by the movable end
of the spring,
the actuator actuating the switch when the movable end reaches a predetermined
position
within the lubricator, the predetermined position being reached when the
plunger return force
is equal to or greater than a predetermined plunger return force.
[0004] According to another aspect, the actuator may comprise a disc
carried by the
movable end of the spring.
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[0005] According to another aspect, the switch may be attached at the top
end of the
lubricator body and may be in axial alignment with the lubricator body.
[0006] According to another aspect, the switch may be actuated by metal to
metal contact
between the actuator and the top end of the lubricator body.
[0007] According to another aspect, the predetermined plunger return
force may be
indicative of an alarm condition.
[0008] According to another aspect, the lubricator assembly may further
comprise a
controller that receives the signal generated by the switch, and the
controller may be
programmed to shut in the well upon receiving the signal from the switch.
[0009] According to another aspect, the actuator may actuate the switch
when the spring
is fully compressed.
[0010] According to another aspect, the actuator may actuate the switch
when the spring
is partially compressed.
[0011] According to an aspect, there is provided a method of shutting in
a well having a
wellbore, a lubricator assembly, and a plunger, the lubricator assembly
comprising a
lubricator body having a bottom end in communication with a well, a top end
and one or more
production flow ports, the method comprising the steps of placing the plunger
in the wellbore
of the well, the plunger travelling through the wellbore in response to the
pressure in the well,
such that in response to sufficient pressure, the plunger travels from the
well into the
lubricator assembly, the plunger returning to the lubricator assembly with a
plunger return
force, fixing a spring within the lubricator body and above the one or more
flow production
ports, the spring having a movable end and a fixed end above the movable end,
the spring
being compressible in a longitudinal direction, the spring compressing in
response to the
plunger return force, attaching an actuator to the movable end of the spring,
determining a
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predetermined plunger return force, positioning a switch above the movable end
of the spring,
the switch generating a signal when actuated, and calibrating the actuator to
actuate the switch
when the movable end of the spring reaches a predetermined position within the
lubricator,
the predetermined position being reached when the plunger return force is
equal to or greater
than the predetermined plunger return force.
[0012] According
to another aspect, the actuator may comprise a disc carried by the
movable end of the spring.
[0013] According
to another aspect, the switch may be attached at the top end of the
lubricator body and may be in axial alignment with the lubricator body.
[0014] According
to another aspect, the switch may be actuated by metal to metal contact
between the actuator and the top end of the lubricator body.
[0015] According to another aspect, the predetermined plunger return force
may be
indicative of an alarm condition.
[0016] According
to another aspect, the method may further comprise the step of
providing a controller that receives the signal generated by the switch, the
controller being
programmed to shut in the well upon receiving the signal from the switch.
[0017] According
to another aspect, the actuator may actuate the switch when the spring is
fully compressed.
[0018] According to another aspect, the actuator may actuate the switch
when the spring is
partially compressed.
[0019] In other
aspects, the features described above may be combined together in any
reasonable combination as will be recognized by those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
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[0020] These and other features will become more apparent from the
following
description in which reference is made to the appended drawings, the drawings
are for the
purpose of illustration only and are not intended to be in any way limiting,
wherein:
FIG. 1 is a side elevation view in section of a lubricator assembly with a
plunger
at a lower position.
FIG. 2 is a side elevation view in section of a lubricator assembly with a
plunger
at an intermediate position.
FIG. 3 is a side elevation view in section of a lubricator assembly with a
plunger
at an upper position.
DETAILED DESCRIPTION
[0021] A lubricator assembly, generally identified by reference numeral
10, will now be
described with reference to FIG. 1 through 3. Lubricator assembly 10 is part
of a system with
a plunger 34 that may be used with a hydrocarbon producing well 16, such as a
gas well, in
order to assist with production of fluids from well 16.
[0022] Referring to FIG. 1, lubricator assembly 10 has a lubricator body
12 with a bottom
end 14 in communication with well 16, a top end 18, and one or more production
flow ports
20. As shown in FIG. 1, lubricator body 12 has two production flow ports 20.
The number of
production flow ports 20 may vary depending on the application and the type of
lubricator
and well. Lubricator body 12 has a spring 22 carried within lubricator body 12
above the one
or more production flow ports 20. Spring 22 has a movable end 24 and a fixed
end 26 above
the movable end 24. Spring 22 is compressible in a longitudinal direction, and
compresses in
response to a plunger return force, as shown in FIG. 2. As shown, spring 22 is
a longitudinal
coil spring. While the advantages of using such a spring in the described
example are
apparent, it will be understood that other types of springs also be used.
[0023] Lubricator body 12 has a switch 28 that detects when plunger 34
arrives at a high
rate of speed. In particular, switch 28 is used to detect with spring 22 is
compressed to a
particular point by the kinetic energy of plunger 34. In the depicted example,
this is done by
placing switch 28 at a point above movable end 24 of spring 22 to be actuated
by an actuator
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30 when spring 22 is sufficiently compressed. Switch 28 may be positioned at
various points
on lubricator body 12 above movable end 24 of spring 22. In the depicted
example, referring
to FIG. 1, switch 28 is located at the top end of lubricator body 12 in axial
alignment with
lubricator body 12. Alternatively, switch 28 may be located at various
positions spaced down
5 from the top end of lubricator body 12, and may be attached along the
sidewall of lubricator
body 12. Switch 28 generates a signal when actuated, such as a sound, a visual
signal, a signal
to a computer monitoring system, or the like. While the signal generated may
be intended to
notify an operator, it may also be used to cause a computer processor to
record an event, or
both, depending on the requirements and preferences of the user. In a
preferred embodiment,
switch 28 may be a contact switch, or a proximity sensor, such as a reed
switch that is
actuated based on the present of a magnet. It will be understood that switch
28 acts to identify
an alarm condition, and that other types of switches or sensors may be used,
such as a sensor
that is designed or programmed to send a signal when a particular condition is
reached.
[0024] Spring 22 carries an actuator 30 at movable end 24 that actuates
switch 28 when
movable end 24 of spring 22 reaches a predetermined position within lubricator
body 12. The
predetermined position is reached when the plunger return force is equal to or
greater than a
predetermined force, indicative of an alarm condition. Actuator 30 may take a
variety of
forms, as will be understood by those skilled in the art. For example,
actuator 30 may be a
disc carried by movable end 24 of spring 22 that triggers a switch or acts as
a switch when in
the predetermined position. Referring to FIG. 3, the predetermined position
may be
determined by the dimensions of actuator 30. As shown, actuator 30 may contact
top end 18
of lubricator body 12. Switch 28 may be actuated by metal to metal contact
between actuator
and top end 18 of lubricator body 12. Switch 28 may also be actuated by direct
contact
25 between actuator 30 and a component of switch 28. Switch 28 may also be
actuated, for
example, by actuator 30 passing a certain height in lubricator body 12. Switch
28 may be
designed in a variety of ways as will be recognized by those skilled in the
art. For example,
switch 28 may be a physical switch, a proximity switch, etc. In some cases,
switch 28 may be
actuated before spring 22 is fully compressed, where switch 28 is actuated at
any point along
30 the compression path of spring 22 that is desired. This may provide an
extra safety area with
further compression available, or may serve other purposes. For example,
lubricator body 12
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may have two switches 28, the first being placed at a midpoint along the
compression path of
spring 22, and when movable end 24 of spring 22 passes the first switch 28,
actuator 30
actuates the first switch 28, and the first switch 28 communicates with a data
recording device
to record the impact for review. A second switch 28 may be placed at a higher
point along the
compression path of spring 22, for example, at or near the top 18 of
lubricator body 12. When
actuator 30 actuates second switch 28, second switch 28 may generate an alarm
condition and
shut in the well.
[0025] Referring to FIG. 3, movable end 24 of spring 22 may reach the
predetermined
position when the predetermined plunger return force exceeds a given value.
For example,
predetermined plunger return force may be indicative of an alarm condition
requiring the well
to be shut in for repair or diagnosis. Lubricator assembly 10 may have a
controller 32 that
receives the signal generated by switch 28, and controller 32 may be
programmed to shut in
well 16 upon receiving the signal from switch 28, or send an alarm to an
operator to initiate
the shut in. It will be understood that well 16 may be shut in using a variety
of methods
known in the art. The alarm condition could be determined using a variety of
safety
thresholds. For example, the alarm condition could be determined by the
compressibility and
strength of spring 22, in order to prevent a failure condition in spring 22.
As one example,
actuator 30 may actuate switch 28 when spring 22 is fully compressed.
Alternatively, actuator
30 may actuate switch 28 without having to fully compress spring 22
[0026] Referring to FIG. 1, lubricator body 12 may also have a catcher
assembly 38 for
holding plunger 34 above port 20. Lubricator body 12 may also have a pressure
gauge 40 for
measuring pressure within lubricator body 12. Other accessories and apparatus
may also be
included in lubricator boy 12, depending on the needs of the user and the
application for the
plunger assembly.
[0027] In operation, plunger 34 is placed in wellbore 36 of well 16, and
plunger 34 travels
through wellbore 36 in response to the pressure in well 16. When the pressure
below plunger
34 is sufficient, plunger 34 travels up through well 16 and into lubricator
assembly 12. The
speed of plunger 34 will determine the force with which it returns. In order
to prevent damage
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or avoid unsafe conditions caused by the plunger returning with too high a
force, the system is
designed to trigger a switch when plunger 34 returns with a force greater than
a
predetermined value and compresses spring 22 sufficiently. Actuator 30 is
attached to spring
22, and is calibrated such that actuator 30 actuates switch 28 when a
predetermined position is
reached by movable end 24 of spring 22. The predetermined position is
determined by the
predetermined plunger return force, and is achieved when the plunger return
force is equal to
or greater than the predetermined plunger return force.
[0028]
Activating switch 28 may cause well 16 to be shut in and an alarm condition
generated so that well 16 may be diagnosed and repaired as necessary. The
compression of
spring 22 is directly related to the force applied to spring 22 by plunger 34,
and thereby
indicates the force with which the plunger is returning to the surface.
Controller 32 may be
programmed to respond differently in response to different scenarios. For
example, controller
32 may trigger an alarm for review by maintenance personnel in response to a
single high
impact that activates switch 28, and may close in well 16 only in response to
a second high
impact that equals or exceeds the predetermined plunger return force.
Different responses to
activation of switch 28 will be understood by those skilled in the ar.
[0029] 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 that more than one of the elements is present, unless the context
clearly requires
that there be one and only one of the elements.
[0030] The scope of the following claims should not be limited by the
preferred
embodiments set forth in the examples above and in the drawings, but should be
given the
broadest interpretation consistent with the description as a whole.
