Note: Descriptions are shown in the official language in which they were submitted.
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HIGH-VELOCITY DISCHARGE EQUALIZING SYSTEM AND METHOD
BACKGROUND
The present invention relates generally to wellbore production enhancement
operations and, more particularly, to a high-velocity discharge equalizing
system and method.
Various procedures have been utilized to increase the flow of hydrocarbons
from
subterranean formations penetrated by wellbores. For example, a commonly used
production
enhancement technique involves creating and extending fractures in the
subterranean
formation to provide flow channels therein through which hydrocarbons flow
from the
formation to the wellbore. The fractures are created by introducing a
fracturing fluid into the
formation at a high flow rate and high pressure in order to exert a sufficient
force on the
formation to create and extend fractures therein. Solid fracture proppant
materials, such as
sand, are commonly suspended in the fracturing fluid so that upon introducing
the fracturing
fluid into the formation and creating and extending fractures therein, the
proppant material is
carried into the fractures and deposited therein, whereby the fractures are
prevented from
closing due to subterranean forces when the introduction of the frac fluid
ceases.
In the line that transports the fracturing fluid from the pumps to the
wellhead, there is
typically a pipe tee that facilitates the use of a return line that transports
fluid to a pit or other
fluid containment when so desired. A valve that controls flow through this
additional line
may be inadvertently opened during high-flow and high-pressure situations,
such as hydraulic
fracturing. This may cause the energized fluid flowing through the line to
surge out through
the end, which may create undesirable reaction forces that cause the line to
move
uncontrollably. Anchors are sometimes used to minimize movement of the line.
SUMMARY
According to one embodiment of the invention, a high-velocity fluid discharge
device
includes tubing having one or more orifices formed therein, a shroud coupled
to the tubing
such that, when a fluid flowing through the tubing exits the orifices, the
fluid impinges on an
inside surface of the shroud, and openings at both ends of the shroud. The
openings have
substantially the same areas.
Some embodiments of the invention provide numerous technical advantages. Some
embodiments may benefit from some, none, or all of these advantages. For
example,
according to certain embodiments, high-flow discharge of fluid due to an
inadvertent opening
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of a valve on the line running to a pit or fluid containment during hydraulic
fracturing or
other high pressure operations may be equalized so as to avoid excessive
movement of the
end of the line, which leads to a safer environment. In some embodiments, a
shield may be
utilized with such an equalizing system to prevent exiting fluids from
throwing projectiles on
location as well as provide additional anchorage into the ground.
The features and advantages of the present invention will be readily apparent
to those
skilled in the art upon a reading of the description of the exemplary
embodiments that
follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial plan view of a production enhancement system utilizing a
high-flow
discharge equalizing device in accordance with one embodiment of the present
invention;
FIG. 2 is a cross-sectional view of the equalizing device of FIG. 1 in
accordance with
one embodiment of the present invention; and
FIGS. 3A and 3B are perspective views of an equalizing device in accordance
with
another embodiment of the present invention.
DESCRIPTION
FIG. 1 is a partial plan view of a production enhancement system 100 utilizing
a high-
flow discharge equalizing device 200 in accordance with one embodiment of the
present
invention. In the illustrated embodiment, system 100 is being utilized to
perform a hydraulic
fracturing operation; however, system 100 may be utilized for any suitable
well stimulation
treatment or production enhancement operation in which fluid is circulated
through a well
(not illustrated).
System 100 includes one or more pumps 102 that deliver a fracturing fluid or
other
suitable fluid to a wellhead 104 via delivery line 106 having an associated
valve 107. Because
of the nature of hydraulic fracturing, the fluid is typically a high-flow,
high-pressure fluid. In
one embodiment, the fluid is flowing at a pressure of at least 100 psi and may
be a gas,
homogeneous foam, a liquid, or co-mingled fluid and gas. System 100 also
includes a
discharge line 108 having an associated valve 109 that is utilized to deliver
fluid to a pit 110,
which may be any suitable fluid containment, when so desired.
According to the teachings of one embodiment of the invention, system 100
includes
discharge equalizing device 200 that creates a pressure-balanced exit
condition for the fluid
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flowing out of the open end of discharge line 108 into pit 110. Details of
discharge equalizing
device 200 are described in further detail below in conjunction with FIG. 2.
Discharge equalizing device 200 may also include a shield 208 to shield any
exiting
fluids flowing out of discharge equalizing device 200 and also to serve as a
restraint system
by anchoring discharge equalizing device 200 into the ground. Although not
illustrated,
additional anchorage systems may be associated with discharge line 108 for
anchoring
discharge line 108 into the ground.
FIG. 2 is a cross-sectional view of discharge equalizing device 200 in
accordance with
one embodiment of the invention. In the illustrated embodiment, discharge
equalizing device
200 includes a tubing 202 having a plurality of orifices 203, a shroud 204, a
reinforcing pad
206, and shield 208.
Tubing 202 may be any suitable conduit operable to transport a fluid
therethrough.
Tubing 202 may be any suitable size and shape and may be formed from any
suitable
material. In one embodiment, tubing 202 has a diameter between approximately
two and
three inches. The fluid flowing through tubing 202 flows in the direction of
arrow 210 and
escapes from tubing 202 through orifices 203, as indicated by arrows 211.
Orifices 203 may
be any suitable size and there may be any suitable number of orifices 203. In
one
embodiment, there are multiple sets of orifices 203 longitudinally spaced
along tubing 202,
with each set of orifices 203 including a plurality of orifices equally spaced
around a
circumference of tubing 202. For example, orifices 203 may be spaced around
the
circumference of tubing 202 at an angular spacing of 30 , 60 , 90 , or 180
depending on the
number of orifices in each set. Orifices 203 may also be offset from one
another. The present
invention contemplates any suitable arrangement of orifices 203 formed in
tubing 202.
In a particular embodiment of the invention, tubing 202 may have a buffer zone
212
associated with its downstream end in which there are no orifices. Buffer zone
212 thus
facilitates the reduction of the fluid shock exiting orifices 203 by smoothing
the transition
from zero pressure to high pressure. In other words, as fluid starts exiting
orifices 203 buffer
zone 212 begins to fill up with fluid so that the full pressure of the fluid
does not immediately
exit orifices 203, but instead builds up progressively.
Shroud 204 couples to tubing 202 in any suitable manner. Shroud 204 may be any
suitable size and may be formed from any suitable material. In one embodiment,
shroud 204
is formed from ten inch casing; however, other suitable diameters may be
utilized. In
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addition, shroud 204 may have any suitable length. In the illustrated
embodiment, shroud 204
couples to tubing 202 with an end cap 214 at the downstream end of tubing 202
and an
entrance cap 216 at the upstream end. In order for the fluid existing in
shroud 204 to exit
shroud 204, end cap 214 includes a downstream opening 215 and entrance cap 216
includes
an upstream opening 217. Although both downstream opening 215 and upstream
opening 217
may have any suitable open areas, downstream opening 215 and upstream opening
217 have
substantially the same open areas. This facilitates the pressure-balanced exit
condition. In
some embodiments, shroud 204 may not be uniform, but may have openings along
its length.
Because the fluid flowing through tubing 202 is flowing at high velocity, and
because
orifices 203 have a relatively small diameter, a great force may be exerted on
an inside wall
218 of shroud 204. This may cause deterioration of the wall of shroud 204
depending on
many factors, such as the thickness of shroud 204, the type of material shroud
204 is formed
from, the type of fluid flowing through tubing 202, the velocity of fluid, and
the size of
orifices 203. Therefore, reinforcing pad 206 may be coupled to an outside
surface 220 of
shroud 204 in a location corresponding to where the fluid impinges on inside
surface 218.
Reinforcing pad 206 may also couple to inside wall 218 of shroud 204 as a
sacrificial insert.
Reinforcing pad 206 may be any suitable size and shape, may be formed from any
suitable
material, and may couple to shroud 204 in any suitable manner. In lieu of
reinforcing pad
206, the wall thickness of shroud 204 may be increased or the type of material
that shroud
204 is formed from may be changed.
Shield 208 functions to act as a shield for any fluid exiting upstream opening
217 of
shroud 204, and may also act as an anchorage system for discharge equalizing
device 200 by
imbedding a portion of shield 208 into the ground. Shield 208 may be any
suitable size and
shape and may be formed from any suitable material.
In operation of one embodiment of the invention, a high flow fluid flows
through
tubing 202 in the direction of arrow 210. The fluid starts exiting orifices
203 and quickly fills
up buffer zone 212 before the full pressure of the fluid exiting orifices 203
starts impinging
upon inside wall 218 of shroud 204 that counteracts the reaction force
generated by the
exiting of the fluid through orifices 203. Fluid then exits out downstream
opening 215 and
upstream opening 217 before being deposited into pit 110 (FIG. 1). The fluid
flowing out of
downstream opening 215 and the fluid flowing out of upstream opening 217
create
substantially equal but offsetting forces. This offsetting of forces creates a
pressure-balanced
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exit condition for discharge equalizing device 200 and prevents the end of
discharge line 108
from moving uncontrollably. Therefore, a safer environment may be facilitated.
In another embodiment of the invention, illustrated in FIG. 3B, tubing 302 is
shown
with equally spaced orifices 303 and no shroud 204 exists. In this embodiment,
the fluid
flowing through tubing 302 exits through orifices 303, and since these
orifices have equal
open areas and equally spaced, then the forces caused by the fluid flowing out
of orifices 303
offset each other, thereby facilitating a pressure-balanced exit condition.
In another embodiment of the invention, which is not illustrated in the
figures, tubing
202 does not have orifices 203 formed therein and no shroud 204 exists. In
this embodiment,
a tee is coupled to the end of tubing 202 so that when the fluid flowing
through tubing 202
exits the end orifice of tubing 202, it exerts a force on the inside of the
tee and then flows out
both ends of the main branch of the tee. If these ends of the tee have equal
open areas, then
the forces caused by the fluid flowing out of the ends offset each other,
thereby facilitating a
pressure-balanced exit condition.
FIGS. 3A and 3B are perspective views of a discharge equalizing device 300 in
accordance with another embodiment of the present invention. Discharge
equalizing device
300 is similar in function to discharge equalizing device 200; however,
discharge equalizing
device 300 includes a collection tank 308 that supports both ends of a tubing
302. In the
illustrated embodiment, discharge equalizing device 300 includes tubing 302
having one or
more orifices 303, a shroud 304, a pair of shields 306a, 306b, a lifting eye
307, a removable
plug 310, and collection tank 308.
The description of tubing 302, orifices 303, and shroud 304 is substantially
similar to
the discussion of tubing 202, orifices 203, and shroud 204 as found in FIG. 2
and, hence, is
not described again.
Shields 306a, 306b, are also similar to shield 208 of FIG. 2; however, in the
embodiment illustrated in FIG. 3A, shield 306a is placed adjacent an upstream
opening 317
of shroud 304 and shield 306b is placed adjacent a downstream opening 315 of
shroud 304.
Shields 306a, 306b create a symmetry in discharge equalizing device 300 that
facilitates the
balancing of the resultant forces from fluid exiting upstream opening 317 and
downstream
opening 315.
The ends of tubing 302 may be coupled to collection tank 308 in any suitable
manner.
Collection tank 308, along with lifting eye 307, facilitates the portability
of discharge
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equalizing device 300. As such, discharge equalizing device 300 may be mounted
on a truck,
trailer, a skid, or other suitable vehicle for easy transportation.
Although collection tank 308 may have any suitable size and shape, in one
embodiment, collection tank 308 includes a top 314 disposed underneath tubing
302 and
shroud 304 to collect the fluids exiting shroud 304. In a particular
embodiment, top 314 has a
concave surface to assure that forces on collection tank 308 are downward. In
any event, top
314 includes a plurality of drain holes 316 that direct the fluid down into
collection tank 308.
Collecting fluid in collection tank 308 also facilitates added weight to
discharge equalizing
device 300, which aids in anchoring the device. A drain 318 may be coupled
near a bottom of
collection tank 308 to facilitate the draining of the fluid contained therein.
As illustrated in FIG. 313, tubing 302 may include a buffer zone 320 that
functions in a
similar manner to buffer zone 212 of tubing 202 (FIG. 2). Removable plug 310
functions as a
clean-out for tubing 302 and may be any suitable removable plug that couples
to the
downstream end of tubing 302 in any suitable manner.
In operation of one embodiment of the invention illustrated in FIGS. 3A and
3B, fluid
having a high velocity flows through tubing 302 in the direction as indicated
by arrow 322.
The fluid starts exiting orifices 303 and eventually fills up buffer zone 320
before the full
pressure of the fluid is exiting out orifices 303. The fluid impinges upon the
inside surface
323 of shroud 304 and exits shroud 304 via downstream opening 315 and upstream
opening
317 before hitting shields 306a and 306b. The fluid is then directed in all
directions and some
of the fluid collects on top 314 of collection tank 308. The fluid then drains
through drain
holes 316 into collection tank 308 where it may be stored or drained off using
drain 318. As
described above, the fluid exiting orifices 303 exerts a force on the inside
surface 317 of
shroud 304 that offsets the reaction force generated by the fluid flowing out
of orifices 303.
This may create a pressure-balanced exit condition for tubing 302.
Although some embodiments of the present invention are described in detail,
various
changes and modifications may be suggested to one skilled in the art. The
present invention
intends to encompass such changes and modifications as falling within the
scope of the
appended claims.
