Note: Descriptions are shown in the official language in which they were submitted.
Atty Dkt No. 002740-5028
ZIPPER BRIDGE
TECHNICAL FIELD
[0001] The present disclosure relates generally to oil or gas wellbore
equipment, and, more
particularly, to a connector bridge for a frac manifold.
BACKGROUND
[0002] Frac manifolds, also referred to herein as zipper manifolds, are
designed to allow hydraulic
fracturing operations on multiple wells using a single frac pump output
source. Frac manifolds
are positioned between the frac pump output and frac trees of individual
wells. A frac manifold
system receives fracturing fluid from the pump output and directs it to one of
many frac trees.
Fracturing fluid flow is traditionally controlled by operating valves to
isolate output to a single
tree for fracking operations.
[0003] Frac zipper manifolds may be rigged up to frac trees before frac
equipment arrives at the
well site. Once onsite, the frac equipment need only be connected to the input
of the frac manifold.
Because individual frac trees do not need to be rigged up and down for each
fracking stage and
because the same frac equipment can be used for fracking operations on
multiple wells, zipper
manifolds reduce downtime for fracking operations while also increasing safety
and productivity.
Another benefit includes reducing equipment clutter at a well site.
[0004] Despite their benefits, further efficiencies and cost savings for
zipper manifolds may be
gained through improved designs. In particular, typically treatment fluid in
the zipper manifold
passes to frac trees via goat heads or frac heads and frac iron, but there are
several drawbacks to
using such setups to span the distance between the zipper manifold and each
frac tree. Goat heads,
or frac heads, traditionally employ multiple downlines and restraints that
clutter the area between
the zipper manifold and the frac tree, which can make for a more difficult and
less safe work
environment to operate and maintain the frac equipment.
[0005] Some designs have been developed to avoid using frac iron. One design
uses a single line
made from studded elbow blocks and flow spools with swiveling flanges. Such a
design is
disclosed in, for example, U.S. Patent Nos. 9,932,800, 9,518,430, and
9,068,450. A similar design
is currently offered for sale by Cameron International of Houston, Texas,
under the brand
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name Monoline. One drawback of this design is that the weight of the equipment
combined with
the potentially awkward orientation of the lines can make installation
difficult and can place
uneven or increased stress on the connections to the frac manifold and/or the
frac tree. Another
drawback is that using a single line to connect the frac manifold to the frac
tree can lead to
increased velocity and turbulence of the flow, when compared to using multiple
lines. Such
conditions may lead to a greater risk of erosion in the frac tree. Replacing a
damaged frac tree can
be very expensive and time-consuming. Accordingly, what is needed is an
apparatus, system, or
method that addresses one or more of the foregoing issues related to frac
zipper manifolds, among
one or more other issues.
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SUMMARY OF THE INVENTION
[0006] The frac zipper manifold uses a dual passage bridge to connect from a
zipper manifold to
a frac tree. With this bridge design, multiple frac iron lines between the
zipper manifold and the
frac tree are eliminated while providing for a robust, durable connection
which may be adjusted to
accommodate different configurations of zipper manifolds and frac trees.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Various embodiments of the present disclosure will be understood more
fully from the
detailed description given below and from the accompanying drawings of various
embodiments of
the disclosure. In the drawings, like reference numbers may indicate identical
or functionally
similar elements.
[0008] FIG. 1 illustrates a zipper manifold as known in the prior art.
[0009] FIG. 2 illustrates one embodiment of an improved dual spool connection
from a zipper
manifold to a frac tree.
[0010] FIG. 3 illustrates the bridge connector header used in conjunction with
one embodiment of
the improved dual spool connection shown in FIG. 2.
[0011] FIGS. 4A-4E illustrate one method of installing a short spool and
threaded flange on the
lower side of a T-junction.
[0012] FIGS. 5A-5E illustrate one method of installing short spools, threaded
flanges, and studded
blocks on either side of the axial throughbore of a T-junction.
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DETAILED DESCRIPTION
100131 FIG. 1 illustrates an example of a prior art zipper manifold 100. The
manifold may be
positioned vertically, as shown in FIG. 1, or it may be positioned
horizontally. The frac
manifold 100 can include two or more well configuration units 101. Each well
configuration
unit 101 includes one or more valves 102 and a connection header 103, and the
well configuration
units 101 may be collectively or individually (as shown) positioned on skids
106. Each connection
header 103 connects to a similar header on the frac tree. Prior art connection
headers 103 are often
called frac heads or goat heads and include multiple fluid connection points,
as shown in FIG. 1.
Each fluid connection point attaches to a downline 110 that is routed to the
ground before turning
back up and connecting to a connection point on the frac tree header 270 of
the frac tree 200. The
use of downlines 110 allows operators to adjust for different distances
between and relative
locations of the frac manifold 100. The downlines 110 typically have small
diameters, which
limits the flow therethrough. The multiple lines and the restraints for those
lines create clutter
between the zipper manifold and the frac tree, which can make maintenance
difficult and increase
safety concerns. Each well configuration unit 101 typically includes a
hydraulically actuated
valve 102a and a manually actuated valve 102b. The well configuration units
101 of the zipper
manifold 100 are connected together by zipper spools 104, and the final zipper
spool 104 may be
capped off or connected to other well configurations 101 as needed. The zipper
manifold 100
connects to the output of the frac pump at the frac supply header 105.
[0014] In operation, the valves 102 of one well configuration unit 101 are
opened to allow fluid
flow to the corresponding frac tree 200 through its connection header 103
while the valves 102 of
other well configuration units 101 in the zipper manifold 100 are closed. The
valves 102 may be
closed and opened to control the flow through different well configuration
units 101 of the zipper
manifold 100.
[0015] FIG. 2 illustrates an exemplary embodiment of a well configuration unit
210 with an
improved bridge connector header 230. The bridge connector header 230, which
connects to a
frac tree, forms a "T" junction 215 with a short spool extending upward from
valve 102a. The T-
junction 215 of the bridge connector header 230 connects to two studded blocks
250. Each studded
block 250 joins to a bridge spool 255 that connects similarly to studded
blocks 250 and a frac tree
header 270 on the frac tree.
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[0016] As shown in more detail in FIG. 3, the bridge connector header 230
includes threaded
flanges 235 on each side of the "T"¨right, left, and bottom¨connected via
short spools 238. The
threaded flanges 235, which are able to be rotated, are lined up with a
corresponding flange or bolt
holes during install. The threaded flanges 235 engage threads on the outer
surface of the short
spools 238, but the external threads include excess threading to allow for
additional rotation of the
threaded flange 235 to allow it to orient to the desired position. For
example, the threaded
flange 235 at the bottom of the T is aligned with a corresponding flange on
the well configuration
unit 210, and bolts are used to secure the flanges together. A studded block
250 is similarly joined
to each of the right and left sides of the T-junction of the bridge connector
header 230 via a short
spool 238 and threaded flanges 235.
[0017] The threaded flanges 235 allow the T-junction of the bridge connector
header 230 and
associated parts to be oriented into a desired configuration before final
assembly of the bridge
connector header 230. The threaded flange 235 at the bottom allows the bridge
connector
header 230 to be rotated about the central axis of the of the well
configuration unit 210 (indicated
in FIG. 2 as the y-axis), which may also be referred to as azimuthal rotation.
Azimuthal rotation
about the y-axis allows the entire T-junction, along with both bridge spools
255, to be laterally
adjusted in order to accommodate a potential horizontal misalignment between
bridge connection
header 230 and frac tree header 270.
[0018] The threaded flanges 235 on the right and left sides of the T-junction
allow bridge
spools 255 to be rotated about the central axis running horizontally through
the T-junction
(indicated in FIG. 2 as the z-axis), which may also be referred to as vertical
rotation. Vertical
rotation about the z-axis allows the distal end of bridge spools 255 to be
adjusted up or down to
accommodate a potential vertical misalignment between bridge connection header
230 and frac
tree header 270.
[0019] Internally, the T-junction splits the supply fluid flow to the two
studded blocks 250, which
are elbow shaped to route the flows to the bridge spools 255. The frac fluid
travels through the
bridge spools 255 to the studded blocks 250 on the frac tree side, and the two
flows are rejoined at
the frac tree header 270 of the frac tree 200. Significantly, when the two
flow streams enter the
frac tree header 270 of the frac tree 200, they enter from opposite
directions. As a result, the
velocity vectors of both streams will, to some degree, cancel each other out.
This cancellation
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effect results in a lower velocity of the combined flow stream within frac
tree 200, as compared to
the velocity that would result from the use of a single spool connector.
[0020] In simulations performed by the applicant, the configuration shown in
FIG. 2, with each
bridge spool having a 5-inch inner diameter and an overall flow rate of 100
barrels per minute, the
flow velocity in the upper portion of frac tree 200, immediately below T-
junction 290, was in the
range of 32-38 feet per second.
[0021] In a separate simulation, bridge spools 255 were replaced with a single
bridge spool
running in a straight line between bridge connector 230 and frac tree header
270. The single bridge
spool was simulated with an inner diameter of 7 inches, such that it had the
same cross-sectional
area as the combination of bridge spools 255 (49 in2 vs 50 in2). At the same
simulated rate of 100
barrels of fluid flow per minute, the flow velocities seen at the same point
within frac tree 200
were significantly higher than the dual-spool configuration, generally
exceeding 38 feet per second
and in certain areas exceeding 45 feet per second.
[0022] The dual-spool configuration shown in FIG. 2 should also result in
lower turbulence of the
combined flow stream within frac tree 200. The lower velocity and lower
turbulence should reduce
the risk of erosion within frac tree 200, as compared to a flow stream within
a single spool
connector.
[0023] Installation of the improved connector bridge can be performed in
several different ways.
In one method, the first step in the installation process, as shown in FIG.
4A, is to securely attach
lower threaded flange 235 to the top of well configuration unit 210, just
above valve 102a, using
bolts 280. Next, as shown in FIG. 4B, short spool 238 is attached to threaded
flange 235 by rotating
short spool 238 until the threaded portion 282 is fully engaged with the
complementary threaded
portion 284 of threaded flange 235. Next, as shown in FIG. 4C, upper threaded
flange 235 is
attached to short spool 238 by rotating upper threaded flange 235 until the
threaded portion 284 is
engaged with the complementary threaded portion 282 of short spool 238. Next,
as shown in
FIG. 4D, upper threaded flange 235 is attached to bridge connector header 230
using bolts 280.
At this point, if necessary, bridge connector header 230 is rotated
azimuthally about the y-axis,
such that it aligns correctly with the frac tree to which the bridge spools
are intended to connect.
Such azimuthal rotation is accomplished by the threaded connection between
upper threaded
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flange 235 and short spool 238, as shown in FIG. 4E. Once bridge connector
header 230 is
correctly aligned, all bolts and connections are securely tightened.
[0024] In this installation method, the next step, as shown in FIG. 5A, is to
securely attach an inner
threaded flange 235 on either side of bridge connector header 230, using bolts
280. Next, as shown
in FIG. 5B, a short spool 238 is attached to each threaded flange 235 by
rotating short spool 238
until the threaded portion 282 is fully engaged with the complementary
threaded portion 284 of
threaded flange 235. Next, as shown in FIG. 5C, an outer threaded flange 235
is attached to each
short spool 238 by rotating outer threaded flange 235 until the threaded
portion 284 is engaged
with the complementary threaded portion 282 of short spool 238. Next, as shown
in FIG. 5D, each
outer threaded flange 235 is attached to a studded block 250 using bolts 280.
At this point, if
necessary, studded blocks 250 are rotated vertically about the z-axis, such
that they align correctly
with the studded blocks 250 on the frac tree to which the bridge spools are
intended to connect.
Such vertical rotation is accomplished by the threaded connection between
outer threaded
flanges 235 and short spools 238, as shown in FIG. 5E. Once studded blocks 250
are correctly
aligned, all bolts and connections are securely tightened. During this stage
of the installation
process, bridge spools 255 may be attached to studded blocks 250 either before
or after studded
blocks 250 are attached to outer threaded flanges 235.
[0025] In another installation method, the bridge spools 255, studded blocks
250, bridge connector
header 230, and frac tree header 270 may all be pre-assembled at the well
site. A crane is used to
lower the entire assembly onto the well configuration unit 210 and the frac
tree 200, where it may
be connected. If there are elevation differences between the bridge connector
header 230 and the
frac tree header 270, the rotating threaded flanges 235 may be used to adjust
the elevation at either
end.
[0026] The zipper bridge is superior to other methods of connecting the zipper
manifold to the frac
trees for multiple reasons. Because its orientation may be adjusted in one or
both of the azimuthal
and vertical directions, it can accommodate variations in the distance between
and configuration
of different frac manifolds and frac trees. Because it comprises two bridge
spools, it does not
require the multiple downlines used in many prior art systems. It is easier to
install and more
stable than other large-diameter hardline connections because its design is
simpler and does not
involve post-installation adjustments, and also because it is symmetrical
about a line running from
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the well configuration unit to the frac tree. Because it comprises two flow
lines that enter the frac
tree header from opposite directions, it decreases the risk of erosion as
compared to prior art
systems using a single flow line.
[0027] It is understood that variations may be made in the foregoing without
departing from the
scope of the present disclosure. In several exemplary embodiments, the
elements and teachings of
the various illustrative exemplary embodiments may be combined in whole or in
part in some or
all of the illustrative exemplary embodiments. In addition, one or more of the
elements and
teachings of the various illustrative exemplary embodiments may be omitted, at
least in part, and/or
combined, at least in part, with one or more of the other elements and
teachings of the various
illustrative embodiments.
[0028] Any spatial references, such as, for example, "upper," "lower,"
"above," "below,"
"between," "bottom," "vertical," "horizontal," "angular," "upwards,"
"downwards," "side-to-
side," "left-to-right," "right-to-left," "top-to-bottom," "bottom-to-top,"
"top," "bottom," "bottom-
up," "top-down," etc., are for the purpose of illustration only and do not
limit the specific
orientation or location of the structure described above.
[0029] In several exemplary embodiments, while different steps, processes, and
procedures are
described as appearing as distinct acts, one or more of the steps, one or more
of the processes,
and/or one or more of the procedures may also be performed in different
orders, simultaneously
and/or sequentially. In several exemplary embodiments, the steps, processes,
and/or procedures
may be merged into one or more steps, processes and/or procedures.
[0030] In several exemplary embodiments, one or more of the operational steps
in each
embodiment may be omitted. Moreover, in some instances, some features of the
present disclosure
may be employed without a corresponding use of the other features. Moreover,
one or more of the
above-described embodiments and/or variations may be combined in whole or in
part with any
one or more of the other above-described embodiments and/or variations.
[0031] Although several exemplary embodiments have been described in detail
above, the
embodiments described are exemplary only and are not limiting, and those
skilled in the art will
readily appreciate that many other modifications, changes and/or substitutions
are possible in the
exemplary embodiments without materially departing from the novel teachings
and advantages of
the present disclosure. Accordingly, all such modifications, changes, and/or
substitutions are
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intended to be included within the scope of this disclosure as defined in the
following claims. In
the claims, any means-plus-function clauses are intended to cover the
structures described herein
as performing the recited function and not only structural equivalents, but
also equivalent
structures.
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