Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02865992 2014-09-26
CLOSURE FOR FLUID PORTS IN A PRODUCTION TANK
TECHNICAL FIELD
[0001] This relates to a closure for fluid ports in a production tank,
such as test cocks or
fluid outlets.
BACKGROUND
[0002] Production tanks are used to store fluids produced from a well.
These wells
include outlet, including larger outlets for transferring the produced fluids
for transport, and
other smaller outlets used for withdrawing samples of fluid, such as for
testing purposes.
These outlets are often referred to as test cocks. Sometimes test cocks are
not closed properly
after use, in which case leaks can occur. If left uncorrected, the leak can
result in significant
environmental damage.
SUMMARY
[0003] According to an aspect, there is provided a production tank,
comprising a tank
enclosure defined by a roof, a floor and a sidewall, at least one fluid inlet
in fluid
communication with the tank enclosure, at least one fluid outlet in fluid
communication with
the tank enclosure comprising, a primary valve that has a first actuator for
opening and
closing the primary valve, and a secondary valve in line with the primary
valve, the secondary
valve having a second actuator for opening and closing the secondary valve,
the second
actuator being biased toward a closed position, a fluid container disposed
below the at least
one fluid outlet, a controller connected to the at least one secondary valve,
the controller
maintaining the at least one secondary valve in an open position when
activated and the
controller permitting the at least one secondary valve to move to the closed
position when
deactivated, a sensor in communication with the fluid container configured to
deactivate the
controller when a predetermined fluid condition is sensed within the fluid
container.
[0004] According to another aspect, the controller may comprise a
pressurized gas in
fluid communication with the second actuator of the at least one secondary
valve, the
pressurized gas maintaining the at least one secondary valve in the open
position, and the
controller may be deactivated by releasing the gas pressure against the second
actuator.
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[0005] According to another aspect, the controller may comprise an
electrical power
source, the at least one secondary valve comprises a solenoid valve, and the
controller may be
deactivated by de-energizing the solenoid valve.
[0006] According to another aspect, the sensor may comprise a float that
detects the
presence of liquid in the fluid container.
[0007] According to another aspect, the production tank may further
comprise a
deactivation switch on an outer surface of the production tank and spaced from
the at least
one fluid outlet.
[0008] According to another aspect, the fluid container may comprise an
outlet enclosure
that encloses the at least one fluid outlets and is recessed within the tank
enclosure relative to
the sidewall.
[0009] According to an aspect, there is provided a production tank,
comprising a tank
enclosure defined by a roof, a floor and a sidewall. There is at least one
fluid inlet in fluid
communication with the tank enclosure and at least one fluid outlet in fluid
communication
with the tank enclosure. The at least one fluid outlet comprising a primary
valve that has a
first actuator for opening and closing the primary valve, and a secondary
valve in line with the
primary valve, the secondary valve having a second actuator for opening and
closing the
secondary valve. A fluid container is disposed below the at least one fluid
outlet. A control
arm is connected to the at least one secondary valve. The control arm moves
between a raised
closing position in which the at least one secondary valve is closed and a
lowered opening
position in which the at least one secondary valve is opened. A float carried
by the control
arm and positioned within the fluid container applies an upward force to the
control arm when
a predetermined level of fluid is in the fluid container such that the control
arm closes the at
least one secondary valve.
[0010] According to another aspect, the production tank may further
comprise at least
one deactivation lever connected to the at least one secondary valve and
positioned outside
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the production tank and spaced from the at least one fluid outlet.
[0011] According to another aspect, the fluid container may comprise an
outlet enclosure
that encloses the at least one fluid outlets and is recessed within the tank
enclosure relative to
the sidewall.
[0012] According to another aspect, the at least one secondary valve may
be biased to the
closed position and is maintained in the open position until released by the
controller.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] 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 of a production tank.
FIG. 2 is a detailed front plan view of the outlets of a production tank.
FIG. 3 is a detailed front plan view of the outlets of a production tank after
fluid
has leaked.
FIG. 4 is a side elevation view of an alternative production tank.
FIG. 5 is a detailed front plan view of an alternative set of outlets.
DETAILED DESCRIPTION
[0014] A production tank generally identified by reference numeral 10,
will now be
described with reference to FIG. 1 through 5. While the description and
drawings relate to a
particular design, it will be understood that the shutoff valves described
herein may be applied
to other types and designs of production tanks as known in the art.
[0015] Referring to FIG. 1, production tank 10 has a tank enclosure 12
defined by a roof
14, a floor 16 and a sidewall 18. There is shown fluid inlet 20 in fluid
communication with
tank enclosure 12, although there may be more than one. Fluid inlet 20 is
designed to be
connected to a source of fluid, such as a well (not shown), and to receive the
fluids produced
from the well. When connected to a well, the produced fluids will include
sand, water, liquid
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hydrocarbons, and possibly some gaseous hydrocarbons. Depending on the demands
place
on the well, there may be some initial separation prior to depositing the
fluids into the
production tank, although any separation steps taken at this time will not
remove all of a
single component. As shown in FIG. 1, there is a sand layer 22, a water layer
24, an oil layer
26, and a gas layer 28. Gas layer 28 may be ambient air, gaseous hydrocarbons
from the
production fluids, or more commonly, a mixture of both. The components of
produced fluids
and how the components are managed are well known in the art and will not be
described
further.
[0016] In the oil and gas industry, production tanks arc used to store
fluids until the fluids
can be transported. There may be more than one production tank on a site, and
the production
tanks will generally have more features than what is shown. In particular,
there is generally a
series of vents and access points on the top of a production tank, and there
may be fluid level
indicators or sensors, and the like. In the depicted example, production tank
10 is shown with
a single vent 32 on roof 14, which may be, for example, a thief hatch. Thief
hatches are used
to provide internal access to tank enclosure 12, and generally include a two-
way pressure
relief valve to prevent over- or under-pressurization of production tank 10,
as production
tanks are generally designed to hold the necessary amount of fluid, but are
not designed to be
pressure vessels. Also shown in some embodiments is a smaller enclosure 34
that is recessed
within sidewall 18 but is isolated from tank enclosure 12. One suitable type
of enclosure is
sold under the name Enviro-VaultTM. Generally, enclosure 34 is used to enclose
connections,
as shown in FIG. I, to protect them from damage and from the elements, as the
fluids in
enclosure 12 are generally heated, which will also heat enclosure 12.
Enclosure 34 may also
be used as a liquid container, as shown in FIG. 3 and will be described in
greater detail below.
[0017] As shown,
production tank 10 has outlets 36 with corresponding risers 38 that
extend to different heights. Outlets 36 allow an operator to withdraw fluids
from different
layers within enclosure 12. While
three outlets 36 are depicted with risers 38 at three
different heights, there may only be two, or any number as desired by the
user. Referring to
FIG. 1, outlets 36 are positioned within enclosure 34. Enclosure 34 acts as a
fluid container
for receiving overflow fluids and catching any drips or leaks that may occur
while removing
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fluid from tank enclosure 12 through outlets 36.
[0018] In addition to outlets 36, production tank 10 also has testing
outlets 40 with
corresponding risers 42. Testing outlets 40 are smaller than outlets 36 and
are used to
5 withdraw test samples. Outlets 40 may be referred to as test cocks. The
shutoff system is
described below with respect to test cocks 40. It will be understood that the
system may also
be applied to outlets 36.
[0019] Referring to FIG. 2, each outlet 40 has a primary valve 44 with a
first actuator 46,
which is a handle as shown that is manually operated to open and close primary
valve 44.
Each outlet 40 that also has a secondary valve 48 in line along outlet 40 with
primary valve
44. Secondary valve 48 has a second actuator 50 that opens and closes
secondary valve 48.
As shown, second actuator 50 is a line that connects to secondary valve 48.
Second actuator
50 is biased toward a closed position. Secondary valve 48 may take various
forms, and the
actual details of secondary valve 48 and second actuator 50 are not shown. Two
examples of
secondary valves include a fluid-actuated valve, such as a pneumatic valve,
hydraulic valve,
or a solenoid valve. Each of these may be biased toward the closed position
such that, when
fluid pressure is released, in the case of a fluid-actuated valve, or the
circuit broken, as in the
case of a solenoid valve, the valve closes. In the depicted embodiment, line
51 is a pneumatic
air line connected to a pressurized air cylinder 52, which acts as a
controller for secondary
valve 48. If secondary valve 48 were a solenoid valve, controller 52 would be
a power
source, such as a battery.
[0020] Under normal operation, controller 52 maintains secondary valve 48
in an open
position. In the case of a pressurized air cylinder, this is done by
maintaining air pressure to
secondary valve 48, and in the case of a battery or power source, this is done
by maintaining a
current to the solenoid valve. Once the air pressure has been shut off or
released, or the
current turned off secondary valve 48 will close. A normally-closed valve is
used in order to
ensure that, if the system were to be in a failure condition, secondary valve
48 would close
until repaired.
[0021] In order to determine when controller 52 allows secondary valves
48 to close, a
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sensor 54 is provided in communication with the fluid container configured to
deactivate the
controller when a predetermined fluid condition is sensed within the fluid
container 34. As
shown, sensor 54 is a float that is connected by an arm 56 to controller 52.
As the fluid level
in fluid container 34 rises, float 54 will move upward until a certain level
is reached, at which
point controller 52 will allow secondary valves 48 to close. This may be done,
for example,
by having arm 56 open a valve that evacuates the pressurized air in controller
52, or it may
turn a three way valve that closes controller 52 and vents line 51. When
necessary to re-
pressurize controller 52, this may be done using a compressor that is often
present on well
sites. In the case of an electric controller, the batteries may be recharged
using solar or wind
power, for example, or may be connected to a generator or other electrical
equipment that is
commonly used on well sites.
[0022] In addition to sensor 54, controller 52 may be signalled by a
secondary
deactivation switch 58 on an outer surface of production tank 10 and spaced
from fluid outlets
40. Secondary switch 58 may be useful if a remote shutdown of secondary valves
48 is
required, such as if there is a risk of fire or explosion. Referring to FIG.
4, secondary switch
58 may be on an outer surface of the production tank 10, or spaced from the
production tank
10, or both. For example, secondary switch 58 may be on or close to a truck
used to haul
fluid from production tank 10. This allows an operator to shut secondary
valves if a safety
hazard were to occur requiring that the flow of fluid be shut down without the
operator having
to approach production tank 10. As will be understood, secondary switch 58 may
be a push
button, a lever, or other types of actuators as part of an air hose, hydraulic
hose, a cable, push
rod, etc. that are able to act on controller 52.
[0023] When secondary valves 48 are pneumatic valves, controller 52 may be
connected
by a hose to the pneumatic system of the vehicle. In this embodiment, when
controller 52 is
activated by either float 54 or secondary switch 58, it will also shut down
the vehicle to
further reduce the danger.
[0024] Referring to FIG. 5, in another embodiment, secondary valves 48 may
be
mechanically closed, such as by a lever. As shown, controller 52 is a lever
that pivots as float
54 moves up and down and opens and closes valves 48. In this embodiment,
secondary
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switch 58 is preferably a mechanical type of switch that either acts directly
on controller 52 or
acts directly against secondary valves 48 to close them. In this embodiment,
secondary valves
may be controlled by controller 52 and/or secondary switch 58 or may be biased
to the closed
position, where, when controller 52 or secondary switch 58 is activated,
secondary valves 48
close and must be reset before resuming normal operation.
[0025] 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.
[0026] 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.
