Note: Descriptions are shown in the official language in which they were submitted.
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OILFIELD PRODUCTION TANK WITH DIVIDED INTERIOR AND TOP-TO-
BOTTOM FLUID TRANSFER PASSAGE BETWEEN DIVIDED SPACES
FIELD OF THE INVENTION
The present invention relates generally to production storage tanks
used in the oilfield to store hydrocarbon-containing fluids produced from a
well, and
more particularly to such a tank in which the interior is divided into
separate spaces
that respectively fed and drained by the tank inlet and outlet.
BACKGROUND OF THE INVENTION
It is known in the prior art to provide an oilfield production tank whose
interior is divided into two separate volumes by an internal vertical baffle,
as
disclosed in Canadian Patent Application No. 2,665,578 entitled Dual
Production
Tank. The tank features a fire tube in each of the space to aid in separation
of the
oil, water and sand of the incoming production fluid.
However, there remains room for improvement, and Applicant has
developed a unique divided production tank not heretofore seen.
Other prior art relevant to processing of the raw well fluids to separate
out the components same can be found in CA2108297, US5042582 and
US5928519, but these involve initial separation of gases and liquids prior to
storage,
and thus involve use of high pressure vessels unlike the minimal or zero-
pressure
production storage tanks with which the present invention is concerned.
U.S. Patent No. 3,340,477 discloses a separation tank for water-oil
separation of produced emulsions of a hydrocarbon liquid and aqueous solution,
but
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employs a structure notably different than the production tank of the present
invention.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided an oilfield
production tank comprising:
a tank enclosing an interior;
a divider arrangement mounted at a location within the tank and
dividing a first space of the interior from a second space of the interior
over a
majority of a height of the tank at the location of the divider;
a fluid passage having a fluid passage inlet positioned within the first
space of the interior of the tank on a first side of the divider at a first
height nearer an
upper end of the divider than a lower end of the divider, and a fluid passage
outlet
that opens into the second space of the interior of the tank on a second side
of the
divider at a second height that is lower than the first height;
a tank inlet opening into the interior of the tank on the first side of the
divider for ingress of produced well fluid into the tank through said tank
inlet;
a tank outlet opening into the interior of the tank on the second side of
the divider for egress of fluid from the tank through said tank outlet.
Preferably the divider arrangement comprises an upright baffle.
The fluid transfer passage may be defined by a downcomer that is
engaged with an opening in the baffle to deliver fluid from the first space to
the
second space through the upright baffle at said opening therein.
The downcomer may extend through the opening.
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In one embodiment, the downcomer engages with the opening in the
baffle at a height closer to the fluid passage inlet than to the fluid passage
outlet,
and runs downwardly from said height on the second side of the upright baffle.
There may be provided a control mechanism operable to adjust the
first height at which the fluid passage inlet is located in order to control a
fluid level to
which the first space will fill before reaching the fluid passage inlet.
In one embodiment, the control mechanism comprises:
a sleeve slidably disposed over an upright length of pipe that forms a
portion of the fluid passage; and
at least one inlet opening that opens into an interior of said sleeve at
an area of the sleeve that is movable within a range of heights disposed above
the
top end of the upright length of pipe.
The control mechanism may further comprise an actuator operable to
raise and lower the sleeve to adjust a position of the inlet opening of the
sleeve
relative to the top end of the upright length of pipe.
The actutator of the control mechanism may comprise a control linkage
having an input end and an opposing output end coupled to the sleeve for
sliding
movement thereof along the length of upright pipe under movement of the input
end
of the control linkage.
The actutator of the control mechanism may comprise a control lever
having an input end, an opposing output end and a pivot point between the
input and
output ends, the output end being coupled to the sleeve by an intermediate
link for
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sliding movement thereof along the length of upright pipe under pivotal
movement of
the input lever about the pivot point.
The input end of the control linkage may be positioned externally of the
tank for manual manipulation of the input end from outside the tank.
In another embodiment, the control mechanism may comprise a
tubular elbow having a first end thereof that is coupled by a swivel joint to
an inlet
end of a lateral length of pipe that forms part of the fluid passage to enable
pivoting
of the tubular elbow about an axis of the swivel joint to adjust a height of
an
opposing second end of the tubular elbow relative to the inlet end of the
lateral
length of pipe.
The lateral length of pipe may extend through the divider arrangement
from the first side thereof to the second side thereof, at which the lateral
length of
pipe is joined to an upright section of pipe running downwardly along the
divider
arrangement toward the fluid passage outlet.
The control mechanism may comprise an actuator comprising an
elongated flexible lift member having an output end thereof coupled to the
tubular
elbow from above for raising of the second end of the tubular elbow under
pulling of
the elongated flexible lift member.
The elongated flexible lift member may be routed to an exterior of the
tank for operation of the control mechanism from outside the tank by manually
driven
pulling of the elongated flexible lift member.
Preferably the control mechanism comprises a locking device operable
to lock a position of the fluid passage inlet at a selected height.
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Preferably there is a fluid pathway between the first and second
spaces at an elevation spaced above the inlet of the fluid transfer passage.
The upper end of the divider arrangement is preferably spaced below
an upper end of the interior of the tank to leave an open space defining the
fluid
5 pathway between the upper end of the divider arrangement and the upper
end of the
interior of the tank.
Preferably the divider arrangement reaches fully to a bottom of the
interior of the tank in order to separate the first and second spaces entirely
from one
another over an area spanning from the bottom of the interior of the tank to
the
upper end of the divider arrangement.
Preferably the tank inlet is disposed at a lower elevation than the fluid
passage inlet.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which illustrate exemplary
embodiments of the present invention:
Figure 1 is a side elevational view schematically showing an oilfield
production tank of a first embodiment of the present invention in cross-
section.
Figure 2 is an elevational view schematically showing an oilfield
production tank of a second embodiment of the present invention in cross-
section.
Figure 3 is an elevational view schematically showing an oilfield tank of
a third embodiment of the present invention in cross-section.
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Figure 4 is a partial elevational view showing a variant of the first
embodiment tank which features a first type of control mechanism for
controlling
transfer of fluid from one divided space of the tank interior to another.
Figure 5 is a partial elelvational view showing a variant of the third
embodiment tank which features a second type of control mechanism for
controlling
the transfer of fluid between the divided spaces of the tank interior.
DETAILED DESCRIPTION
Figure 1 schematically shows an oilfield production tank 10 according
to a first embodiment of the present invention. The tank may have the same
cylindrical outer shape as conventional production tanks, where a cylindrical
outer
wall 12 circumscribes a cylindrical interior volume of the tank at barometric
pressure.
A top wall 14 overlies the cylindrical interior volume of the tank, and may
have a
peaked or domed configuration delimiting a headspace overtop of the
cylindrical
volume bound by the circumferential outer wall 12.
A vertical baffle 16 stands upright from a floor 17 that lies opposite the
top wall 14 and defines the bottom of the tank's interior volume. The
illustrated
baffle 16 stops short of the top wall 14 of the tank, leaving an open space
between
an upper end 16a of the baffle 16 and the top wall. An L-shaped pipe or
assembly of
pipes defines a downcomer 18 having a first vertical leg 18a that depends
downwardly along the baffle 16 on a first side thereof at a distance outward
therefrom, and a second horizontal leg 18b that is integrally or otherwise
attached to
the lower end of the first leg to turn at an angle therefrom in a lateral
direction
passing through the baffle 16. The open end 20 of the first leg 18a of the
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downcomer 18 defines an inlet of the downcomer on the first side of the
baffle, and
the open end 22 of the second leg 18b of the downcomer forms an outlet thereof
on
the second side of the baffle.
Over the height of the interior volume that is spanned by the baffle, the
interior volume is divided into two separated spaces on the respective sides
of the
baffle. The downcomer thus fluidly communicates with the first space on the
first
side of the baffle only at the downcomer inlet 20 near the top end 16a of the
baffle,
and fluidly communicates with the second space of the second side of the
baffle at
the downcomer outlet 22 near where the lower end of the baffle 16 is attached
to the
floor 17 of the tank interior.
A tank inlet 24 opens into the tank interior on the first side of the baffle
through the circumferential wall 12 at a height thereon near, but spaced
above, the
tank floor 17 at an elevation thus located well below the downcomer inlet 20.
A tank
outlet 26 similarly opens into the interior space, but on the second side of
the baffle
16. Accordingly, the tank inlet 24 feeds into the first space of the tank
interior, while
the tank outlet 26 instead communicates with the second space of the tank
interior.
Produced well fluids are conveyed into the tank interior, specifically into
the first of
the two divided spaces thereof, through the tank inlet 24 via an input line
coupled
thereto (not shown). This incoming production fluid may contain oil, water,
gas and
sand. As is well known in the art, these materials will tend to separate from
one
another once fed into the tank, with the sand sinking to the tank floor and
the water
tending to separate from the oil. Due to differences in density, the oil will
tend to rise
through the water, resulting an upper layer of oil disposed over an
intermediate layer
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of water residing atop the sand and any other debris or particulate on the
tank floor
17. The natural process does not result in complete separation, and so it will
be
appreciated that the top 'oil layer' is not entirely composed purely of clean
oil, but will
contain some sand and water content, just as the water layer is not entirely
devoid of
oil and sand.
As shown a burner tube 28 may extend into the first space of the tank
interior in a known manner for heating of the production fluid contents, which
is
known to aid in the separation of the oil/water emulsion and sand mixture. The
burner tube may be situated at an intermediate height above that of both the
tank
inlet 24 and the horizontal leg 16b of the downcomer, but well below that of
the
downcomer inlet 20. Injected chemical treatments to aid in the separation
process
may also be employed in a known manner.
As the separation process progresses during filling of first interior
space with the incoming production fluid mixture, the top oil layer rising
toward the
upper end 16a of the baffle 16 on the first side thereof eventually reaches
the
downcomer inlet 20, at which point the relatively clean oil of this upper
layer will
begin to drain down through the downcomer, thus feeding into the second
interior
space on the second side of the baffle near, but spaced above, the tank floor
17. As
mentioned above, this 'relatively clean' oil from the first side is expected
to still
contain some contaminants, but the natural separation process will continue on
this
second side of the baffle. A second burner tube 30 may extend into the second
space of the tank to aid in this further separation of the production fluid
that has
already undergone a first stage of separation in the first space. Accordingly,
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remaining sand or other debris will settle out to the floor of the second
internal tank
space, with the cleanest oil again rising toward the top of the space.
By delivering the fluid from the first space into the second space near
the lower end of the second space, as opposed to having it overflow over the
top of
the baffle, the top layer of oil in the second space will be the cleanest oil
in the tank,
at least until the first tank space tank is filled to a level exceeding the
top end of the
baffle, as this oil has undergone separation in both spaces of the tank, and
the first-
stage oil from the first space has not yet overflowed the baffle onto this
cleanest
second-stage oil at the top of the second space. Accordingly, the Figure 1
shows
the tank outlet 26 situated relatively high in the second interior space of
the tank for
evacuation of the cleanest oil from the tank.
While Figure 1 shows the outlet 26 schematically as a conduit in the
circumferential tank wall at the desired draw-off height, it will be
appreciated that
outlet configurations are known whereby pipe conduits within the tank are
assembled with control valves allowing the operator to draw off tank content
from a
variety of different positions within the tank, and such means may be employed
in a
tank of the present invention. For example, alternative outlet 26' is shown as
an
open end of a length of piping extending down from this opening to a chamber
29
equipped with control valving and a suitable coupling point for a connection
of a
discharge line to draw the clean oil out of the tank from the upper level of
the second
space. Use of an internal chamber to contain valves, heaters, level controls
and spill
containment means is known in the art, as exemplified by U.S. Patent No.
5960826
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assigned to Enviro Vault Ltd, in which sample taps at varying heights in the
tank
allow drawing off of the fluid from different levels therein.
Figure 1 shows the downcomer outlet 22 situated at an elevation below
the second burner tube 30, but also notably spaced above the tank floor 17.
This
5 way, the outlet 22 will tend to feed the oil from the upper layer of the
first space into
the lower end of an oil layer accumulated in the second space, as opposed to
directing this oil into the sand or water accumulation layers nearer the
bottom of the
second space.
Figure 2 shows a second embodiment oilfield production tank 10' of
10 the present invention that differs from the first only in the structure
of the divider and
fluid-transfer arrangement between the two spaces. Instead of a single baffle
and a
downcomer, a pair of baffles 32, 34 are used to both separate the two spaces
of the
tank interior and provide the top-to-bottom fluid transfer from the first
space to the
second space. The first baffle 32 has its lower end attached to the tank floor
17 and
forms a solid barrier over its full area. The second baffle 34 has its upper
end 34a
situated in accordance with that of the single baffle 16 of the first
embodiment. The
upper end 32a of the first baffle 32 is situated at a slightly lower elevation
than that
of the second baffle 34. The second baffle is a split baffle mounted in a
manner
leaving an open space between its lower end 34b and the tank floor 17, or
having on
or more openings in it at its lower end so as to likewise be substantially
open at the
tank floor 17.
The gap 36 between the two parallel vertical baffles defines a fluid
transfer passage having a passage inlet 38 that opens vertically into the
first space
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of the divided tank at the top end 32a of the first baffle 32, and a passage
outlet 40
that opens horizontally into the second space at the lower end 34b of the
second
baffle. The two baffles thus cooperate together to provide both the space-
dividing
function and the fluid transfer function of the baffle and downcomer
combination of
the first embodiment.
Arrangements for guiding the upper level of oil from the first space to
near the bottom of the second space may employ means other than the
illustrated L-
shaped downcomer piping or inter-baffle gap and still provide the equivalent
functionality. In the embodiment of Figure 1, the downcomer pipe may be
removable, and paired with a pluggable pipe-accommodating opening in the
baffle,
whereby the downcomer can optionally be removed and the two spaces entirely
separated over the full baffle area, for example for filling of the two
separated spaces
by two different wells. The illustrated embodiments feature baffles that stop
short of
the top of the tank in order to allow equalization between the two spaces when
once
space is filled up to the top of the baffle, where the fluid content of that
space would
thereby overflow into the other space over the top of the baffle. Other
embodiments
may feature a full height baffle arrangement reaching fully to the top of the
tank,
providing entirely full separation of the spaces other than that the top-to-
bottom fluid
transfer passage provided by the downcomer or other means.
Figure 3 illustrates a third embodiment which, like the first
embodiment, employs a downcomer 118 or riser with horizontal and vertical legs
or
sections that cooperate to transfer fluid from near the top of the first space
to nearer
the bottom of the second space. However, the downcomer 118 differs from that
of
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the first embodiment in that its vertical leg resides entirely on the second
side of the
upright baffle instead of the first. That is, the downcomer inlet is defined
by a
horizontally-opening end 120 of a horizontal pipe leg 118a of the downcomer
that is
engaged in an opening of the upright baffle 116 so as to pass therethrough in
order
to transfer fluid from the downcomer inlet 120 on the first side of the baffle
116 to the
second side of the baffle. Alternatively, the horizontal pipe leg 118a may be
disposed entirely on the second side of the upright baffle and coupled to the
baffle in
a sealed manner around the opening therein without passing through the
opening,
thereby placing the downcomer inlet 120 at the plane of the upright baffle
116.
From the height at which the horizontal pipe leg 118a is engaged with
the opening in the baffle, a vertical pipe leg 118b then turns vertically
downward
from the horizontal pipe 118a in order to run downward along the second side
of the
baffle toward the lower elevation of the downcomer outlet 122, which may be
defined
by a second horizontal pipe leg 118c joined, integrally or otherwise, to the
bottom
end of the second pipe leg 118b in order to extend away from the baffle116
toward
a more central area of the second interior tank space. In this embodiment, the
fluid
entering the downcomer is not guided downward through the cooler lower layers
below it on the first side of the baffle by the vertical pipe leg, but instead
travels
downward through the warmer fluid on the second side of the baffle, thus
acting to
further heat the fluid as it moves through the downcomer piping in order to
improve
the heat-induced separation or cleaning action by using the already twice
burner-
heated fluid on the second side of the baffle to further warm the once burner-
heated
fluid moving through the downcomer, and to conserve heat energy by not passing
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the downcomer fluid through the cooler lower layers in the first space. As
with the
first embodiment, the pipe legs may be integral sections of a unitary length
of bent
pipe, or may be different pipes coupled together, for example by suitable
corner or
elbow fittings.
In addition, each leg of the downcomer need not be purely vertical or
horizontal, but such orientations are described herein to distinguish lateral
lengths of
piping that are intended to convey fluid more horizontally than vertically
from upright
lengths of piping that are intended to convey fluid more vertically than
horizontally.
Each pipe leg or section also need not be purely linear in form in its reach
to or from
a respective corner between horizontal and vertical legs.
Figure 4 illustrates an optional control mechanism 200 of a type usable
on the tank of the first embodiment where the downcomer features a vertical
pipe leg
18a with an open top end 20 on the first side of the baffle 16. The mechanism
200 is
used control the height at which the downcomer inlet is effectively defined,
thus
controlling the level to which the first interior space of the tank is filled
before fluid
starts to transfer into the second space on the other side of the baffle.
The mechanism features a cylindrical sleeve 202 of inner diameter
slightly greater than the outer diameter of the vertical pipe leg 18a so as to
telescopically fit over the vertical pipe leg 18a in coaxial alignment
therewith from the
top end 20 thereof. An annular seal 203 is provided between the vertical pipe
leg
18a and the sleeve 202 to allow a sliding interface between them while
maintaining a
fluid-tight seal of the annular space between them. The sleeve 202 extends a
vertical distance upwardly beyond the open top end 20 of the vertical pipe leg
18a.
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Near the top end of the sleeve 202, one or more slot or window openings 204
open
into the hollow interior of the sleeve through its cylindrical wall. These
openings 204
define the effective downcomer inlet by which fluid enters the downcomer for
guidance of the fluid onward through the open end 202 of the vertical leg
thereof
18a. A top end of the sleeve is closed off by a cap 206 fixed thereon. Inside
the
sleeve, the cap features a resilient material on the underside thereof that
faces
downward toward the open top end 20 of the vertical leg 18a of the downcomer.
Axial sliding of the sleeve 202 along the vertical pipe leg 18a allows
movement of the sleeve into an out off a lowermost position in which the cap
206 fits
over the open top end 20 of the pipe leg 18a and seals this end closed by way
of a
conforming fit of the resilient sealing material on the underside of the cap
with the
annular end face of the pipe leg 18a. Lifting of the sleeve from this pipe-
closing
position initially brings the slot or window openings 204 up into positions
that cross
the elevation of the open end 20 of the pipe leg 18a, and then raises the
openings
204 even further to heights that are spaced upwardly beyond the horizontal
plane of
the open end 20 of the pipe leg 18a. Controlled raising of the sleeve can thus
control the amount of window or slot area of the sleeve that is open above the
top
end of the vertical pipe leg 18a, and then control how far above this vertical
pipe leg
18a the window or slots openings 204 are located. Accordingly, the position of
the
sleeve can control how fast the fluid enters the downcomers upon reaching the
windows or slots of the sleeve when they are positioned at a height crossing
the
plane of the open top end of the vertical leg 18a of the downcomer, or used to
control the effective height of the downcomer inlet by controlling the
distance by
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which the windows or slots 204 of the sleeve 202 are spaced above the open top
end 20 of the downcomer's vertical pipe leg 18a.
The position of the sleeve 202 is controlled by an actuator linkage 208
featuring a control lever 210 carried atop the tank roof, for example as
defined at the
5 exterior top side of the top wall 14 of the tank. A pivot bracket 212
mounted to the
tank roof features a pair of vertically extending lugs between which the
control lever
210 passes, and a pivot pin passes horizontally through the lugs and control
lever
210, whereby the lever is supported for pivotal movement about a horizontal
pivot
axis. An intermediate link 214 has an upper end thereof located outside the
tank
10 and pivotally coupled to an output end of the control lever 210, and a
lower end
coupled to the sleeve 202 inside the tank on the first side of the upright
baffle 16.
The control lever features a handle 216 at an input end thereof opposite the
output
end at which the intermediate link 214 is attached, whereby manual raising of
the
handle 216 at a distance to one side of the pivot bracket 212 causes lowering
of the
15 intermediate link 214, and the sleeve 202 carried thereby, on the second
side of the
pivot bracket 212.
A locking device features an upright roof-mounted plate 218 residing
aside the plane of the control lever and featuring a series of through holes
220
through which a suitable locking pin can be engaged into a corresponding
diametric
through-hole of the control lever 210 in order to lock the lever in a selected
one of a
number of different positions, each of which corresponds to a different
respective
predetermined position of the sleeve 202 on the vertical leg 18a of the
downcomer.
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16
Alternate actuation systems for effecting movement of the sleeve and
locking the same in a selected position may be employed, and may include
actuators of a powered configuration, as opposed to the manually powered
control
linkage of the illustrated embodiment. However, the use of a manually powered
level control mechanism avoids the need for a power source to drive an
electric,
hydraulic or pneumatic actuator. Where a powered actuator is used however,
manual control still may be effected from outside the tank, for example by a
manually operated control valve of a hydraulic circuit or an electronic
controller,
whether onsite or remote, hard wired or wireless, of an electric, electric-
over-
hydraulic, or electric-over-pneumatic actuation system.
Figure 5 illustrates another type of optional control mechanism 300 for
use on the third embodiment tank of Figure 3, where the downcomer features a
horizontal pipe leg 118a with a horizontally-opening end 120 on the first side
of the
baffle 16. The mechanism 300 is again used to control the height at which the
downcomer inlet is effectively defined, thus controlling the level to which
the first
interior space of the tank is filled before fluid starts to transfer into the
second space
on the other side of the baffle.
This embodiment of the control mechanism uses a ninety degree or
other angled pipe fitting 302 to define a tubular elbow of fixed shape having
one end
thereof coupled to the end 120 of the horizontal pipe leg 118a by a swivel
joint 304,
whereby the elbow fitting 302 can be rotated about the central horizontal axis
of the
horizontal pipe leg 118a that lies concentrically with the coupled end of the
elbow
fitting 302. The angled shape of the elbow fitting places the free open end
306 of
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the fitting at position spaced radially outward from this axis in an
orientation causing
the free end 306 of the fitting to face a direction having at least a radial
component
relative to the horizontal axis of the swivel joint. In the illustrated
embodiment, in
which a ninety degree elbow is used, the direction faced by the open free end
306 of
the fitting is purely radial relative to the swivel axis, and the swivel axis
is oriented
purely horizontally. This provides a maximized vertical range of heights
throughout
which the free end 306 of the pipe fitting 302 can be disposed in its rotation
about
the swivel axis. However, other embodiments in which an elbow angle other than
ninety degrees, or a pipe leg and swivel axis that is somewhat angled and not
purely
horizontal, may also be employed while still obtaining height adjustability of
the free
end of the elbow fitting, which effectively defines the downcomer inlet in
this
embodi ment.
Figure 5 shows the elbow fitting 302 in a vertical plane with the free
end 306 facing vertically upward, thus setting the downcomer inlet at its
maximum
possible height above to the open end 120 of the horizontal pipe leg 118a of
the
downcomer. By swiveling the elbow fitting 180-degrees from this position, so
as to
lie in the same vertical plane but with the free end 306 pointing downward,
the
downcomer inlet is set at its minimum possible height disposed below the open
end
120 of the pipe leg 118a.
A cable, rope or chain actuator 308 is used to control the position of
the elbow fitting 102. A flexible elongated member 310 such as a rope or chain
is
entrained about a roller or guide member 312, such as a pulley, mounted
externally
of the tank atop the roof thereof. After passing over the guide or roller
member 312,
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18
the flexible rope or chain extends downwardly into the tank interior on the
first side of
the upright baffle 116 through a suitable opening in the top wall 14 of the
tank.
Inside the tank, an output end of the flexible member 310 is attached to the
pipe
fitting 302 at a radial distance outward from the swivel axis, preferably
adjacent the
free open end 306 of the fitting. From this upright span of the flexible
member
passing upward through the top wall of the tank from the pipe fitting, the
flexible
member 310 is redirected laterally outward from this rooftop location toward
the
perimeter of the tank roof, where another roller or guide may direct the
flexible
member downward along the side of the tank from the roof for control of the
actuator
from ground-level.
A user can pull the input end of the flexible member in order to pull
upward on the free end 306 of the elbow fitting 302, thereby swiveling the
elbow
fitting in a direction raising the location of the free end thereof. The
control end of
the flexible member may be attached to a winch or reel, whereby rotation of
the
winch or reel in a winding direction that draws more of the flexible member
onto the
winch or reel performs this inlet-raising pulling action on the elbow fitting,
and a
brake or lock mechanism of the winch or reel is used to lock the selected
position of
the elbow fitting by locking the winch or reel against rotation. Use of a
manually
powered reel avoids need for a power source to operate a powered winch. On the
other hand, a powered actuator may provide increased ease of operation, and
optional electronic control from remote locations. Alternatively, actuator
mechanisms other than the described cable, rope or chain actuator may
alternatively
CA 02857249 2014-07-18
19
be employed to control swiveling of the elbow fitting to adjust the downcomer
inlet
height.
Additional description and commentary on one or more embodiments
are provided as follows.
A baffle installed internally in the tank separates the tank into two
compartments or chambers in order to isolate the fluid until it reaches the
height of
the internal baffle riser or downcomer, which brings the emulsion off the top
of one
side to the bottom of the second section to reduce the contaminants in the
emulsion,
such as bitumen, sand and water (BS&W). The emulsion flows in the tank inlet,
and
the oil rises and flows through the downcomer into the other section of the
tank.
Room above the baffle allows for high fluid/foam equalization in high-level
tank
situations.
The tank can also allow for two wells to be produced into one tank for
cleaning the emulsion and shipping the resulting product. By controlling
levels, this
system can also be used to test one well or the other. In other words, when
producing two wells into the one tank, to meet government testing
requirements, one
could keep the levels of the two spaces low enough, for example for one day a
month, and direct the output of each well into a different tank space for
separate
testing of each by keeping the levels below the downcommer inlet so that no
flow
goes between the separated tank spaces. As another option, by removing the
downcomer, which operates as an equalizer once the first space has been
sufficiently filled to reach the downcomer inlet, two wells can be produced
into the
one tank with the open area at the top being used to avoid external tank
overflow by
CA 02857249 2014-07-18
having the filled space overflow into the other space, whereupon continued
filling
can rise up into the headspace of the tank.
The invention can be used at single oil wells, oil well pad sites, and oil
well treating facilities. While the illustrated embodiments feature a
cylindrical tank
5 divided into substantially equal halves, other tank shapes and relative
sizing of the
divided spaces may alternatively be employed.
Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same made
within the spirit and scope of the claims without department from such spirit
and
10 scope, it is intended that all matter contained in the accompanying
specification shall
be interpreted as illustrative only and not in a limiting sense.
