U.S. patent application number 15/852355 was filed with the patent office on 2018-06-28 for manifold and swivel connections for servicing multiple wells and method of using same.
The applicant listed for this patent is ISOLATION EQUIPMENT SERVICES INC.. Invention is credited to Boris (Bruce) P. CHEREWYK.
Application Number | 20180179848 15/852355 |
Document ID | / |
Family ID | 62624916 |
Filed Date | 2018-06-28 |
United States Patent
Application |
20180179848 |
Kind Code |
A1 |
CHEREWYK; Boris (Bruce) P. |
June 28, 2018 |
MANIFOLD AND SWIVEL CONNECTIONS FOR SERVICING MULTIPLE WELLS AND
METHOD OF USING SAME
Abstract
A system and method is provided for maintaining a live bore
throughout a manifold while alternating between fluid flow to a
stimulated wellbore and to an inactive or resting wellbore. At
least two fluid inlets deliver fluid to the live bore, the fluid
inlets straddling the two or more fluid outlets connected to the
respective wellbores. One or more or all of the inlets or outlets
can have multiple flow-impinging ports for reducing fluid velocity
through each port. In another embodiment a method flushing system
is provided for freeze protection for piping for a resting
wellbore. Further, high fluid flow swivel connections between the
manifold and wellheads simplify installation and reduce operational
stresses.
Inventors: |
CHEREWYK; Boris (Bruce) P.;
(Calgary, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ISOLATION EQUIPMENT SERVICES INC. |
Red Deer |
|
CA |
|
|
Family ID: |
62624916 |
Appl. No.: |
15/852355 |
Filed: |
December 22, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62561842 |
Sep 22, 2017 |
|
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|
62438145 |
Dec 22, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 21/02 20130101;
E21B 17/05 20130101; E21B 43/267 20130101; E21B 47/10 20130101;
E21B 33/068 20130101 |
International
Class: |
E21B 33/068 20060101
E21B033/068; E21B 17/05 20060101 E21B017/05; E21B 43/267 20060101
E21B043/267; E21B 21/02 20060101 E21B021/02 |
Claims
1. A system for delivering fluid from a common fluid source to two
or more wellheads, comprising: a manifold having a bore; two or
more fluid outlets in communication with the bore and forming a
live bore at least between the two or more fluid outlets, each
fluid outlet being connected to a corresponding wellhead of the two
or more wellheads and having a respective outlet valve between the
live bore and the corresponding wellhead, the respective outlet
valves being operable to deliver fluid to one wellhead at a time;
and at least first and second fluid inlets straddling the live bore
and connected to the fluid source, wherein when one fluid outlet
and wellhead is blocked at its respective outlet valve, fluid is
delivered to another of the two or more wellheads through the
entire live bore supplied from each of the at least first and
second fluid inlets.
2. The system of claim 1, wherein the bore is an axial bore and the
at least first and second inlets are located adjacent opposing
distal ends of the axial bore, the live bore being formed between
the at least first and second inlets.
3. The system of claim 1, wherein each fluid outlet has two or more
outlet ports.
4. The system of claim 1, wherein each fluid inlet has two or more
inlet ports.
5. The system of claim 4, wherein two or more inlet ports are
opposing for impinging their respective flow of fluid.
6. The system of claim 1, wherein: the at least first and second
inlets are formed in respective first and second fluid inlets and
in communication with an intersecting inlet bore of each of the
first and second fluid inlets; each of the at least one fluid
outlet is formed in a respective fluid outlet and in communication
with an axial outlet bore of each of the fluid outlets; and the
fluid inlet bore and fluid outlet bore are in fluid communication
with each other and comprise at least a portion of the live
bore.
7. The system of claim 1, wherein the first inlet and second inlets
each comprise at least one pair of opposing inlet ports.
8. The system of claim 1, wherein each of the at least one fluid
outlet comprises at least two outlet ports.
9. The system of claim 1, wherein a sum of the cross-sectional flow
area of the inlet ports of the at least first and second inlets is
equal to or less than a cross-sectional flow area of the live
bore.
10. The system of claim 1, wherein a sum of the cross-sectional
flow area of the outlet ports of each of the at least one fluid
outlets is equal to or greater than the cross-sectional flow area
of the live bore.
11. The system of claim 1, further comprising a methanol source in
fluid communication with the at least first and second inlets and
configured to selectively deliver methanol to the live bore and
selected wellheads, and receive returned methanol.
12. The system of claim 11, wherein the methanol is maintained at a
concentration of above 40% methanol.
13. The system of claim 11, wherein the methanol source is fit with
a sump to allow solids to settle therein and a screen to filter out
solids from methanol being delivered to the live bore.
14. A method of delivering a methanol from a methanol source to a
manifold and one or more fracturing stacks of one or more
wellbores, comprising: Isolating a selected fracturing stack from
the wellbore; opening first fluid outlet of the manifold and a
first stack inlet valve of a selected fracturing stack to permit
fluid communication between the manifold and the selected
fracturing stack; opening a return valve of the selected fracturing
stack to permit fluid communication between the selected fracturing
stack and the methanol source; and circulating the methanol from
the methanol source to the manifold, selected fracturing stack, and
back to the methanol source.
15. The method of claim 14, further comprising: actuating the first
fracturing stack inlet valve to the closed position and actuating a
subsequent fracturing stack inlet valve of the selected fracturing
stack to an open position; and circulating methanol through the
subsequent stack inlet valve.
16. The method of claim 14, wherein the step of pumping the
methanol further comprising filtering solids from the methanol
returning to the methanol source.
17. The method of claim 14, further comprising maintaining the
methanol mixture at a methanol concentration of at least 40%
18. A system for fluidly connecting a manifold with one or more
fracturing stacks of one or more wellbores, comprising a plurality
of fracturing lines fluidly connecting a manifold to one or more
fracturing stacks, wherein one or more of the plurality of
fracturing lines comprises at least one flanged swivel joint, each
of the at least one flanged swivel joint having first and second
flanged connections an inside diameter corresponding with that of
the manifold or fracturing stack.
19. The system of claim 18, wherein the one or more swivels
comprise at least three swivels.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent application Ser. No. 62/438,145, filed Dec. 22, 2016 and
U.S. Provisional Patent application Ser. No. 62/561,842, filed Sep.
22, 2017, the entirety of which are incorporated herein by
reference.
FIELD
[0002] Embodiments disclosed herein generally relate to servicing
multiple wells with a fluid and, more particularly, to a system and
method of flowing fluids through manifolds and wellhead assemblies
to minimize the erosive effects of stimulation fluids and
operational difficulties associated with dead zones in components
and piping.
BACKGROUND
[0003] There are an increasing number of subterranean hydrocarbon
reservoirs which are accessed using multiple wells for optimizing
production therefrom. The wells and wellheads connected thereto are
often closely spaced, the wellbores being angled downwardly and
radially outwardly from a central location, such as a pad, to
access as much of the reservoir as possible.
[0004] Many or all of the multiple pay zones in such reservoirs may
be characterized by low permeability or other characteristics which
require stimulation of one or more of the wells for increasing
production therefrom. During selective stimulation of the wells,
which may include fracturing operations performed on one well (an
"active" well), wireline operations may be also be performed on
other wells ("resting" wells), such as to shift wellbore access
from one zone of the well to another. To consolidate pumping
equipment, such as fluid pumpers and sand supply for use in
fracturing, it is known to employ a large common manifold to
selectively connect a source of fracturing fluid to one or more of
the wellheads of the multiple wells. Thus, multiple wells can be
stimulated from a common manifold or trains of multiple manifolds.
Herein frac piping includes the manifold, fluid lines to the
manifold, and frac lines from the manifold to the well. Further,
while various proppants are known, a common proppant is sand, and
herein the term sand is used as shorthand for all proppants.
[0005] To facilitate well stimulation operations on a multiple-well
reservoir, a method called "zipper manifold fracking" is often
used. In a typical zipper manifold fracking configuration, multiple
wells are typically connected to a fracturing fluid pumper through
a manifold and an active well is stimulated while a resting well is
being maintained. During fracturing operations, the manifold is
actuated to fluidly connect a first well W1 to the pumper while the
remaining wells W2 . . . Wn are isolated therefrom.
[0006] The first well W1 is stimulated at a selected stage or zone,
usually starting at the first stage. After stimulation, the
manifold valves are actuated to isolate the first well W1 and
fluidly connect the second well W2 to the pumper for stimulation of
its designated stage, which is typically also its first stage.
While the second well W2 is being stimulated, the first well W1 can
be maintained, manipulated, or both. For example, a wireline can be
run down the first well W1 to set a bridge plug and perforate the
subsequent stage of the first well W1 to prepare it for
stimulation. After stimulation operations are complete at the
designated stage of the second well W2, the second well is isolated
and the first well W1 is once again fluidly connected to the pumper
for stimulation operations on a subsequent stage of the first well.
In the meantime, a wireline can be run down the second well W2 to
set the bridge plug, and perforate the second stage of the second
well. Wells W3 through Wn can be similarly inserted into the
operation. Such operations continue until all desired stages are
stimulated in all desired wells.
[0007] As shown in FIGS. 1A, 1B and 1C, a conventional manifold 10
is provided, used for fracking multiple-well reservoirs. The
manifold, typically receives the entirely of the fracturing fluid
F, from frac fluid source 12, at an inlet 11 mid-point along the
manifold 10. Fluid outlets to the wells are spaced along the
manifold in both directions from the inlet. The frac fluid F
typically travels in a first direction to the outlet for one or
more wells, for example well W1, as shown in FIGS. 1A and 1B, and
then, per operations, flow is switched to travel in a second
direction to one or more other wells, such as well W2, shown in
FIG. 1C. The conventional single operations, as described, result
in localized high velocities of sand laden fluids and alternating
stagnant areas of the manifold.
[0008] The erosive nature of the stimulation fluids F necessitates
regular manifold maintenance. Stimulation fluids F typically have
high fluid flow rates and flow velocity, and are conventionally
directed around right angle corners of manifold fittings and other
components, resulting in significant wear to the manifold, manifold
valves, as well as to downstream equipment. Sand in the fracturing
fluids further exacerbates erosive effects.
[0009] It is known to stockpile replacement manifold components
onsite, including new flow blocks and valves, for replacing damaged
and eroded components as the job proceeds. It is also known to have
redundant fluid pumpers on standby, the redundancy required to
maintain simultaneous and continuous stimulation despite the
increased costs.
[0010] With reference to FIGS. 1B and 1C, in a further
disadvantage, the conventional fluid flow path to the active well
bypasses other unused areas of the manifold, those unused areas
being temporarily dead ended or stagnant. Sand in the current fluid
flow can encroach and accumulate in such stagnant areas. When
operations switch to the next well and fluid is directed through
the recently stagnant areas, the fluid can inject a slug of
accumulated sand downstream to the wellhead and downhole into the
well. Such slugs of sand have been known to damage equipment and/or
obstruct the wellbore stage being stimulated.
[0011] Further, in cold weather environments, freezing can become a
problem during such intermittent fracking operations, as residual
water-based fluid can freeze in the stagnant areas of the frac
piping including the manifold itself, fracturing stack, and various
fluid lines when a well is resting in between fracturing stages. As
it can take hours for stimulation operations to complete in the
active well, fluid in the resting wells has ample time to freeze in
cold conditions.
[0012] To mitigate freezing, it is conventional to wrap heat
tracing such as insulated hot glycol or steam heating hoses around
the various frac piping and the like to warm the components and
fluid therein. However, the installation and use of heating hoses
is time consuming, costly and, should the heater or heating hoses
fail, the entire system could freeze before failure is detected,
necessitating costly repairs and downtime. Typically, installing
heating hoses around a manifold, fracturing stacks, and other
components can take several days. Additionally, as the heat source
is typically a boiler, a failure of the boiler compromises the
entire heating system. Further still, boilers for heating systems
are often controlled remotely, which adds to the risk of delayed
detection failures by personnel.
[0013] The manifold is typically connected to the fracturing stacks
of the multiple wells with one or more frac lines. The tortuous
path of the lines between a manifold and the multiple uniquely
spaced wellhead locations present various challenges, such as a
multiplicity of connections and difficulty of secure installation
in the tightly-spaced, and oft-times elevated environments of
common wellhead equipment configurations.
[0014] The manifold are typically at ground level and the wellhead
connections elevated. Some operators have chosen to employ single,
continuous frac lines with right angle connections to connect a
manifold fluid outlet to each of multiple fracturing stacks,
Unitary, rigid welded lines are efficient in terms of minimizing
connections. However, such unitary connection lines require
precision in order to align and connect to components and other
lines. In some instances, surveying is required to ensure
alignment. Additionally, such lines are extremely rigid and unable
to adequately absorb line jack and vibration, which can result in
excessive stress on the fracturing stack connections, transference
of vibrations from the manifold to the fracturing stack and vice
versa, and otherwise contributing to an unsafe environment.
Further, such lines are subject to substantial erosion and the
unitary line must then be replaced as a whole as opposed to
replacing only worn sections.
[0015] To address deficiencies associated with unitary continuous
lines, some connections in the prior art have utilized swivel
joints. Such joints are characterized by Chiksan.RTM. swivels and
quick release, wing union terminating connections as shown in prior
art FIG. 7. While convenient for quick connection and disconnect,
the nature of the threaded, wing-union connections result in
several deficiencies including: localized bore diameter reduction
at the swivel connections with resultant increased erosive
velocities, introduction of a structural weak point, difficulty in
assembly of the male thread and female wing portions if misaligned,
and troubles associated with the seal.
[0016] The wing union implements rubber seals that can be damaged
by misalignment and in cases, be dislodged into the bore, and
accidental transport down the well with the attendant difficulties
downhole. Further seal loss results in high pressure leakage at
surface, the severity of which can require pumper shut down and a
generally unsafe environment. Further, assembly wing-union
connections require hammering to secure which is difficult in
tightly spaced and elevated locations.
[0017] The pressures and volumes of high pressure frac fluids in
well stimulation place equipment and personnel at risk. There is a
continuing need in the industry for a method to minimize erosion in
the manifold and related frac piping, and to minimize stagnant
areas with the associated sand accumulation and risk of freezing
during down periods and between cycles.
[0018] Further, there is a need for a system and method to easily
connect and disconnect a manifold with wellheads that avoids
imposing local velocity increases, accepts pine movement and
minimizes seal issues.
SUMMARY
[0019] Embodiments herein are directed to an apparatus, system, and
method of selectively stimulating two or more wells from at least
one common fluid source using one or more common manifolds, each
manifold servicing one or more wells. A fluid, such as a fracturing
fluid, is pumped from pumping units through the one or more
manifolds to selected wells of the one or more wells. Manifold
piping includes the manifold, fluid lines to the manifold, and frac
lines from the manifold.
[0020] Herein, fracturing fluid is provided to a live bore of a
manifold at inlets located at each of two or more extremities of
the manifold, typically at each of the opposing ends of a linear
manifold. One or more fluid outlets connect to the fracturing
stacks of the one or more wells are located intermediate the inlets
located at the extremities of the manifold. Thus, fluid is always
flowing in all portions of the live bore regardless of the selected
well, thereby avoiding dead areas for sand and other solids to
accumulate. Further, velocity of the fluid is reduced along a
majority of the manifold as the fluid rate at the inlets is reduced
to at least one half as the fluid supply is split between two
inlets rather than only flowing through one.
[0021] Hence, a nominal 100 units of flow, previously supplied to
one inlet in the prior art, is now supplied to at least two inlets,
having independent flows of 50 units each. In addition to the flow
velocity being reduced by splitting the fluid supply to the
manifold into at least two fluid streams, velocity and energy are
further reduced as the streams converge within the manifold and
impinge on one another as they meet and turn at right angles to
flow out of a manifold outlet to a selected well. In embodiments,
inlets can be arranged in opposing pairs such that fluid streams
entering the manifold through opposing inlets impinge on one
another to provide further velocity reduction. Additional velocity
reduction can be achieved by sizing the inner diameter of the inlet
ports to provide a total cross-sectional area smaller than that of
the cross-sectional area of the live bore, and sizing the inner
diameter of the outlet ports to provide a total cross-sectional
area larger than that of the live bore. Such fluid stream
management, in the form of both reduction of fluid velocity and
energy reduction through impingement and bore sizing, mitigates the
erosive effects of the stimulation fluid on the manifold and
components downstream.
[0022] Simultaneously introducing fluid from opposing ends of a
manifold maintains substantially the entirety of the manifold live
so as to avoid dead areas and buildup of sand, and keeps the
manifold warm, mitigating freezing of fluid within the
manifold.
[0023] In one aspect, a system for delivering fluid from a common
fluid source to two or more wellheads is provided, comprising: a
manifold having an bore and two or more fluid outlets in
communication with the bore and forming a live bore at least
between the two or more fluid outlets, each fluid outlet being
connected to a corresponding wellhead of the two or more wellheads
and having a respective outlet valve between the live bore and the
corresponding wellhead, the respective outlet valves being operable
to deliver fluid to one wellhead at a time. Further, the manifold
comprises at least first and second fluid inlets straddling the
live bore and connected to the fluid source, wherein when one fluid
outlet and wellhead is blocked at its respective outlet valve,
fluid is delivered to another of the two or more wellheads through
the entire live bore supplied from each of the at least first and
second fluid inlets.
[0024] In another embodiment, cyclical operation is protected for
the lines between the manifold and the staged wells as the
operation to each well alternates or cycles between an active and
resting well status.
[0025] In embodiments, a methanol tank and pump can be fluidly
connected to the manifold to flush the manifold and the fracturing
stacks of one or more resting wells with methanol to mitigate and
prevent freezing of fluid therein.
[0026] In another embodiment, a method is provided for delivering
methanol from a methanol source to a manifold and one or more
fracturing stacks of one or more wellbores. The wellhead is
isolated from the wellbore and a first fluid outlet of the manifold
and an inlet valve of a selected fracturing stack are opened to
flow fluid between the manifold and the selected fracturing stack.
A return valve is actuated at the fracturing stack to flow fluid
between the selected fracturing stack and the methanol source and
methanol is circulated from the methanol source to the manifold,
selected fracturing stack, and back to the methanol source.
[0027] In embodiments, one or more flanged swivel joints can be
used to connect fracturing lines between the manifold and the
fracturing stacks of the multiple wells. The flanged swivel joints
can have uniform diameter through bores to avoid local velocity
increases and employ durable ring seals to minimize the risk of
seals being lost during connection or disconnection of the swivel
joint. The flanged swivels enable secure line connection regardless
of the landscape, manifold and wellhead alignments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1A is a schematic representation of a prior art
manifold system;
[0029] FIG. 1B is a schematic representation of a supply of 100
units of frac flow to a first well using a prior art manifold
system;
[0030] FIG. 1C is a schematic representation of a supply of 100
units of frac flow to a second well using the prior art manifold
system of FIG. 1B;
[0031] FIG. 2A is a longitudinal partial cross-sectional view of an
embodiment of a manifold system described herein, illustrating a
common contiguous live bore header and a plurality of outlets
fluidly connected thereto for controlled delivery fluid to multiple
wellheads. A flow path is shown for delivery of fracturing fluid
through the manifold to a first well;
[0032] FIG. 2B is a schematic representation of a supply of 100
units of frac flow to a first well, supplying 50 units from each of
two opposing ends of a linear header or manifold;
[0033] FIG. 2C is a schematic representation of a supply of 100
units of frac flow to a second well, supplying 50 units from each
of two opposing ends of the manifold;
[0034] FIG. 3A is a schematic representation of the relative fluid
velocities at the inlets, outlets and live bore, wherein one half
of the frac fluid is provided at each of the two ends of the live
bore, the selected fluid outlet receiving the total flow for
discharge to the sleeved well, but having two outlet ports, each
outlet port discharging 1/2 of the total flow;
[0035] FIGS. 3B1 through 3B4 respectively are isometric
representations of the management of various fluid flow options for
the schematic of FIG. 3B, namely:
[0036] FIG. 3B1 illustrates an embodiment in which each inlet has
one port for providing 1/2 of the total flow and the fluid outlet
has two outlet ports for discharging 1/2 of the total flow;
[0037] FIG. 3B2 illustrates an embodiment in which one half of the
frac fluid is provided at each end of two ends of the live bore,
one of two inlets providing one inlet port for 1/2 of the total
flow and the second inlet having three inlet ports, each providing
1/6 of the total flow, the second inlet totaling 1/2 of the total
flow;
[0038] FIG. 3B3 illustrates an embodiment in which one half of the
frac fluid is provided at each end of two ends of the live bore,
each of the two inlets have three inlet ports for 1/6 for the total
flow at each port combining to total 1/2 of the total flow at each
inlet;
[0039] FIG. 3B4 illustrates an embodiment in which each inlet has
one port for providing 1/2 of the total flow, and wherein the fluid
outlet has four outlet ports, each of which discharges 1/4 of the
total flow;
[0040] FIG. 4 is a cross-sectional view of a block of the fluid
inlet of FIG. 2A, illustrating inlets for receiving from a fluid
source;
[0041] FIG. 5 is a cross-sectional view of a block of the fluid
outlet of FIG. 2A, illustrating outlets for fluidly connecting to a
wellhead;
[0042] FIG. 6A is a schematic representation of an embodiment of a
methanol flushing system for flushing the manifold and wellhead
components, such as those of FIG. 2A, with the manifold configured
to circulate methanol from a source, through an intermediate fluid
outlet to a first resting well and back to the source;
[0043] FIG. 6B is a schematic representation of the methanol
flushing system of FIG. 6A with the manifold configured to flow
methanol through an intermediate fluid outlet to a second resting
well;
[0044] FIG. 6C is a schematic representation of an embodiment of a
methanol flushing system for flushing the manifold and wellhead
components, with the manifold configured to flow methanol through
an fluid outlet in fluid communication with a respective fracturing
stack;
[0045] FIG. 7 is a flow diagram setting out an example process for
flushing a manifold system and wellhead components with
methanol;
[0046] FIG. 8 illustrates a prior art Chiksan.RTM. swivel
connection with quick release wing union connections;
[0047] FIG. 9 is a cross-sectional view of a swivel connection with
flanged connections according to one embodiment;
[0048] FIG. 10A is a perspective view of the connections between a
manifold and two fracturing stacks employing swivel connections,
each stack having two fracturing lines connecting the stack to the
manifold;
[0049] FIG. 10B is an alternative perspective view of the
connections between a manifold and fracturing stacks of FIG.
9A;
[0050] FIG. 11 is a perspective view of the connections between a
manifold and two fracturing stacks having an alternative swivel
configuration; and
[0051] FIG. 12 is a perspective view of a fracturing stack having
swivel connections to fluidly connect the fracturing stacks and the
manifold.
DESCRIPTION
[0052] Embodiments of a manifold and system for fracturing multiple
wells, and maintenance thereof, are described herein. Embodiments
described herein are suitable for delivery of a variety of
stimulating fluids, but are generally described in the context of
the flow of fracturing fluid in a fracturing operation. Particular
advantages are obtained when using embodiments of the invention for
delivering water-based fracturing fluids F which further carry a
particulate sand P therein. References to sand P include sand and
other proppant typically used in well stimulation operations.
[0053] With reference to FIG. 2A, in an embodiment, a manifold 10
receives frac fluid from a source 12, the manifold comprising an
axial bore 34 formed therethrough. Fluid outlets 40 are spaced
along the manifold and each outlet 40 can have one or more outlet
ports 44 thereabout for fluid communication of frac fluid F between
the bore 34 and wells W. A fluid outlet 40 is assigned to each well
and outlet valves 48 can be positioned adjacent each of the ports
44 of each outlet 40 for selectable discharge of frac fluid F
therefrom. In this manner, each well W1,W2 . . . is independently
connected to the live bore 34 with a respective fluid outlet 40,40
. . . for individually operation or fluid isolation from the live
bore.
[0054] Two or more fluid inlets 30,30 are located on the manifold
10. Each fluid inlet 30 can have one or more inlet ports 38 for
fluid communication of frac fluid F between the source 12 and the
between the bore 34. The fluid inlets 30,30 bookend or straddle all
the fluid outlets 40,40 . . . forming a live bore therebetween. In
operation, the fluid path from any fluid inlet 30 to the furthest
fluid outlet 40, passes every other fluid outlet, so that the
entirely of the manifold bore 34 between the fluid inlets 30,30 has
fluid flowing therein regardless of which well is under
stimulation. Inlet valves 39 can be positioned adjacent each of the
inlet ports 38 selectably permitting frac fluid F from the source
12 to flow therethrough into the manifold 10.
[0055] As shown, in this embodiment, one of the inlet ports 38 of
each fluid inlet 30,30 is in-line with axial bore 34 of the
manifold 10.
[0056] The improved manifold 10 provides fluid flow through the
entire manifold bore 34 regardless of which well W is currently
active. The bore 34 is live and therefore absent stagnant areas.
The live bore 34 prevents accumulation of sand P between the fluid
inlet and fluid outlet to an offline well, and further mitigates
freezing therein.
[0057] Additionally, the velocity of fluid F entering and exiting
the bore 34 can be reduced by fluid inlet 30 and fluid outlet 40
management including strategically sizing and orientation of inlet
ports 38 and outlet ports 44, and selecting the numbers of ports
active on any particular fluid inlet or outlet 30,40. Erosive
effects of the frac fluid F can be minimized at the manifold and
attached manifold piping as described in greater detail below.
[0058] As stated above, the manifold 10 can comprise two or more
fluid inlets 30 located at least at opposing ends 36,36 of the
manifold bore 34. The manifold comprises plurality of spools 52
fluidly connecting the fluid inlets 30 and outlets 40 to form the
continuous bore 34. With reference also to FIG. 4, each of the
fluid inlets 30 has a intersected bore 32 in communication with the
live bore 34 and each of the multiple inlet ports 38 extending
radially therefrom. With reference also to FIG. 5 each of the fluid
outlets 40 have an intersected bore 42 formed in communication with
the live bore 34 and each of the multiple outlet ports 44 extending
radially therefrom. Each of the connectors 52 have a connector bore
formed longitudinally therethrough which is contiguous with the
inlet intersected bore 32 and outlet intersected bore to form the
continuous live bore 34. Connections between fluid inlets 40, fluid
outlets 46, connectors 52, inlet valves 39, and outlet valves 48
can be flanged connections or any other connection means known in
the art for fluidly connecting components.
[0059] While the manifold 10 is comprised of various modular,
discrete components as described herein, one of skill in the art
would understand that manifold 10 can comprise a mixture of
fastened and unitary components, such as welded and bolted
configurations.
Continuous Flow and Flow Impingement
[0060] Returning to FIG. 2A and schematics of FIGS. 2B and 2C,
fluid F is supplied to the inlets 30,30 located at the outboard
ends of the two or more fluid outlets 40,40 of the manifold 10. In
this embodiment, the inlets 30,30 straddle the fluid outlets 40,40,
shown here to be opposing terminal ends 36,36 of the manifold.
[0061] Thus, and with reference to FIGS. 2B and 3A, frac fluid F
traverses the manifold 10 from both ends thereof. For stimulation
of a first well W1 with 100 units of frac fluid, 50 units of fluid
are provided through first inlet and 50 units are provided through
the other, opposing ends of the live bore. The entire live bore of
the manifold is traversed and no stagnant areas result, regardless
of the inactive, or resting second well W2. With reference to FIG.
2B, for stimulation of the second well W3 with 100 units of frac
fluid, 50 units of fluid are provided through first inlet and 50
units are provided through the other, opposing ends of the live
bore. Again, the entire live bore of the manifold 10 is traversed
and no stagnant areas result, regardless of the inactive, or
resting first well W1.
[0062] Further, while avoiding stagnant areas in the bore, the
erosive nature of the 100 units of frac fluid F(100) is reduced.
The majority of the live bore 34 receives a reduced flow rate,
reduced velocity and reduced erosive effects. As two opposing
streams of frac flow F(50),F(50) converge at the fluid outlet 40,
each frac flow F(50) through the fluid inlets 30 is one half the
total full frac fluid flow rate F(100) being supplied to the
manifold 10. As described below, further mitigation of erosion is
accomplished with multiple inlet ports 38 and multiple outlet ports
44.
[0063] As the number of inlet ports increases, the volumetric rate
and velocity of each stream is inversely proportional to the number
of inlets 38. For example, as shown in FIG. 2A, fluid F enters
manifold 10 at two fluid inlets 30 of three inlet ports 38,38,38
each, for six inlet ports total 38. Therefore, there are six
initial fluid streams into the manifold 10, the flow rate of each
stream is about 1/6 of the total fluid flow rate. The three streams
of each fluid inlet 30 converge in the intersecting bore 42 30 to
form a fluid streams having about 1/2 the total fluid flow rate and
travelling at about 1/2 the flow velocity compared to a single
stream. If a third fluid inlet 40 were introduced, such as being
located intermediate along the manifold, then three fluid streams
would be formed in the live bore 34, each at about 1/3 the total
fluid flow rate and velocity.
[0064] As shown in FIGS. 2A, 2B and 2C, even if frac fluid F is
directed to a first well W1 supplied by one or more fluid outlets
40 adjacent one end of the manifold 10, the remainder of the live
bore 34 continues to receive a flow of fluid F, thus avoiding
deposition and accumulation of sand and other solids in any part of
the live bore 34, having general eliminated stagnant or dead flow
areas of any significance. Further, the velocity of the fracturing
fluid F as it travels along the live bore 34 is about one-half the
velocity of fluid flowing through the of the conventional manifold
system 10 of FIGS. 1A to 1C, thereby reducing the erosive effects
of fluid flow on the manifold 10 and other components.
[0065] In the fluid inlet 30, the three streams from ports 38,38,38
converge in the intersecting bore 32 and impinge on each other.
Such impingement reduces further reduces fluid velocity and
dissipates energy to mitigate erosion of the components of the
manifold 10. Similarly, the streams from the opposing fluid inlets
converge at the fluid outlet 40 before discharge through the outlet
ports 44,44 . . . the opposing streams impinging and reducing the
erosive energy.
[0066] In a preferred embodiment, as best shown in FIG. 4, some or
all of the inlet ports 38 are formed in fluid inlets 40 in opposing
pairs such that the fluid streams entering through the opposing
inlet ports 38,38 impinge on one another as they enter the live
bore 34 to further reduce flow velocity and dissipate energy. In
the depicted embodiment, each fluid inlet 40 has four inlets 38
positioned in an opposing arrangement and an additional fifth inlet
38 is oriented in-line with the longitudinal live bore 34. The
reduction in velocity and energy caused by the impinging fluid
streams further aids in reducing the erosive effects of the
fracturing fluid F within the manifold 10 and downstream
equipment.
[0067] By having multiple inlets 38 and outlets 44 formed in each
fluid inlet 40 and fluid outlet 46, respectively, some or all of
the inlet and outlet valves 39,48 can be placed out of axial
alignment with the manifold's live bore 34, allowing easier access
thereto for maintenance, repair, or replacement. This is
particularly advantageous when the stimulation fluid F is a frac
fluid carrying sand, which is highly erosive at high velocity.
Further, by strategically sizing the inlets 38, outlets 44, and
live bore 34 as described in detail below, the valves 39,48 and
other components of the manifold 10 are subjected to lower velocity
flows, reducing wear and erosion.
[0068] The sixing of the various flow paths can further reduce the
erosive effects. Returning to FIG. 4 and with reference to FIG. 5,
the inner diameter and cross-sectional area IBXA of the fluid inlet
30, the cross-sectional area OBXA of the fluid outlet 40, and
cross-sectional areas CXA of the connectors 52 are substantially
equal to and corresponds to the diameter and cross-sectional area
LBXA of the live bore 34. Thus, the live bore cross-sectional
LBXA=IBXA=OBXA=CXA which minimizes flow various and erosion as
fluid F flows through the live bore 34.
[0069] The bore 42 of the fluid inlet 42 can have an internal
diameter IBID defining a total cross-sectional area IBXA. Each of
the one or more inlet ports 38 can have an internal diameter IID,
defining an inlet cross-sectional area IXA. The cross-sectional
area IBXA of the fluid inlet coupled to the live bore is preferably
greater than the total combined inlet cross-sectional area TIXA of
the inlet ports 38 for reducing the velocity of the frac fluid F
entering the fluid inlet 30. Accordingly, as the frac fluid F
travels from the relatively smaller total inlet cross-sectional
area TIXA into the relatively larger live bore cross-sectional area
LBXA, the velocity of the fracturing fluid F decreases.
[0070] With reference to FIG. 5, the intersecting bore 42 of the
fluid outlet 40 can have an internal diameter OBID defining a
cross-sectional area OBXA. Each of the one or more outlet ports 44
has an internal diameter OID defining an outlet cross-sectional
area OXA. A total combined outlet cross-sectional area TOXA of the
outlet ports 44 is preferably greater than the cross-sectional area
OBXA. Accordingly, as the frac fluid F travels from the relatively
smaller cross-sectional area OBXA of the fluid outlet bore 42, into
the relatively larger total outlet cross-sectional area TOXA, the
velocity of the fracturing fluid F is further decreased.
[0071] As above, the sizes of inlet ports 38, outlet ports 44, and
the size of the live bore 34 can be selected to strategically
reduce the velocity of fluid F flowing therethrough. Further, in
embodiments the numbers of inlet ports 38 and outlet ports 44
similarly impact fluid velocities. As shown in FIG. 3B1, two
opposing fluid inlets each provide 1/2 of the nominal flow of frac
fluid, whilst two opposing outlet ports each similarly discharge
1/2 of the nominal flow of frac fluid, combining downstream to
deliver the entire total frac fluid to the well. As shown in FIG.
3B2, simply by a first fluid inlet provides 1/2 of the total flow
and the second inlet is fit with three inlet ports, each providing
1/6 of the total flow totaling 1/2 of the total flow, whilst two
opposing outlet ports each similarly discharge 1/2 of the nominal
flow of frac fluid, combining downstream to deliver the entire
total frac fluid to the well. In FIG. 3B3 each of two fluid inlets
have three inlet ports, for providing 1/6 of the total flow at each
port. Again, two opposing outlet ports each similarly discharge 1/2
of the nominal flow of frac fluid, combining downstream to deliver
the entire total frac fluid to the well. In yet another embodiment,
illustrating effect of the fluid outlet, an embodiment is shown in
which each fluid inlet has one inlet port, each of which provides
1/2 of the total flow; however, the fluid outlet is fit with four
outlet ports, each of which discharges 1/4 of the total flow for
combination downstream.
[0072] The strategic reduction in velocity of the frac fluid F at
key locations greatly reduces the erosive effects on the manifold
10 and downstream equipment. As an added benefit, the smaller
individual outlets 44 can have smaller corresponding valves 48,
which are less expensive, and easier to remove for repair or
replacement.
Methanol Flush
[0073] As above, the bore of the entire manifold remains live,
regardless of which well is being stimulated and which is resting.
Further, a method is described herein for mitigating freezing of
fluids in fracturing lines extending from the manifold 10 to the
wellheads or fracturing stacks of a resting well W.
[0074] With reference to FIGS. 6A, 6B and 6C, in embodiments, a
methanol-containing fluid M can be circulated through manifold 10
and connecting fracturing lines 21 to select fracturing stacks 20
of wellbores W to prevent the freezing of fluid F therein when a
well is in a resting state.
[0075] In more detail a tank 60, from a source of methanol of tank
60 containing methanol M, can be fluidly connected to one or more
inlet ports 38 of manifold 10. One or more pumps 62 can be fluidly
connected to the tank 60 to deliver methanol M to the manifold 10,
select fracturing stacks 20, and back into tank 60. Preferably, the
methanol tank 60 is fluidly connected to the fluid inlets 30,30
located at the opposing end of the manifold 10 such that the entire
manifold live bore 34 is exposed to the methanol M regardless of
which fracturing stack 20 is selected for flushing.
[0076] Fracturing stacks 20 each have at least one stack inlet 22
in communication with at least one respective outlet port 44 of the
manifold 10 via one or more fracturing lines 21. Each inlet can
have a corresponding adjacent gate valve 24 for permitting fluid to
flow therethrough. Fracturing stacks 20 can further comprise an
axial bore 23 in communication with the stack inlets 22 and
generally in-line with the wellbore W. One or more return lines 64
connect the axial bore 23 of each of the frac stacks 20 and the
methanol tank 60, and one or more fluid return valves 66 can be
located adjacent the stack 20 for selectably permitting flow of
methanol M from the axial bore 23 back to the methanol tank 60. A
wellhead valve 29 is located between each of the fracturing stacks
20 and their respective wellbores W for selectably isolating the
axial bore 23 from the wellbore W.
[0077] During methanol flushing operations, the return valve 66 of
the frac stack 20 to be flushed is in the open position and the
wellhead valve 29 is in the closed position, such that methanol M
flows back to the tank 60 via return line 64 instead of into the
wellbore W. In the embodiments depicted in FIGS. 6A-6C, the
fracturing stacks 20 each have multiple inlets, two inlets 22,22
shown.
[0078] In an embodiment, and as shown in in the schematics of FIG.
6A and flow chart of FIG. 7, a process 100 for flushing a manifold
10 connected to a plurality of fracturing stacks 20 with methanol M
is now described. The outlet valves 48 of the manifold 10 can be
actuated to direct fluid to a first fracturing stack 20a to be
flushed (step 102). The return valve 66 of fracturing stack 20a is
actuated to the open position, and the wellhead valve 29 is
actuated to the closed position (step 104). In embodiments where
fracturing stacks 20 have more than one fracturing stack inlet 22,
methanol M is preferably flowed through each fracturing stack inlet
22 individually. Thus, a first gate valve 24 of a first inlet 22 of
frac stack 20a is actuated to the open position to receive methanol
M while all other gate valves 24 remain closed (step 106). Methanol
M can then be pumped through the inlets 38 of manifold 10 and
subsequently flow through the one or more outlets 44 corresponding
with fracturing stack 20a (step 108). After exiting the manifold
10, methanol M continues through fracturing line 21 to the selected
fracturing stack 20a. Methanol M flows into frac stack 20a through
first inlet 22 into axial bore 23, and subsequently is circulated
back to methanol tank 60 via return line 64.
[0079] After flushing through the first inlet 22 is completed, the
gate valve 24 corresponding to the first fracturing stack inlet 22
is closed and, if there are subsequent inlets 22 to flush (step
110), the gate valve 24 corresponding to a subsequent stack inlet
22 is opened for flushing thereof (step 112). Such sequential
flushing of stack inlets 22 continues until all of the gates 24 and
inlets 22 of the fracturing stack 20a have been flushed. This
sequential flushing provides a more thorough exposure of the
components of the fracturing stack 20 to the methanol M.
[0080] Once methanol flushing on first fracturing stack 20a is
completed, return valve 66 and all other valves of the fracturing
stack are closed (step 114) and other operations, such as wireline
or stimulation operations, can be performed on the stack. The
methanol M remaining in the manifold 10 and flushed frac stack 20a
can be shut in to keep the lines filled with methanol M and ready
for the next stimulation or other process. In this manner, methanol
M de-ices and mitigates freezing of residual fluid inside the
manifold 10, fracturing lines 21, fracturing stack 20a, and other
components.
[0081] If it is desired to flush subsequent fracturing stacks 20
(step 116), and as shown in FIG. 6B, manifold 10 can be actuated to
fluidly connect the fracturing stack of a subsequent well, such as
second stack 20b, to methanol tank 60, and the return valve and
wellhead valve of fracturing stack 20b can be actuated to the open
and closed positions, respectively (step 120). The flushing process
can then be performed again for the new stack 20b. The methanol
flushing process can be repeated until the fracturing stacks 20 of
all desired wells W have been flushed.
[0082] Wellhead valve 29 and other lines and equipment therebelow
are not exposed to methanol M. As such components are typically
near the relatively warmer ground area, one can conservatively
install conventional heating around those components for freezing
protection.
[0083] In the context of a multi-well fracturing operation,
methanol flushing can occur at a well W when it is undergoing
maintenance and before wireline operations (e.g. installation of a
bridge plug and perforation). For example, in a zipper manifold
fracturing operation, wherein an "active" well is stimulated while
a "resting well" undergoes maintenance and preparation for a
subsequent stimulation stage, the resting well can first be flushed
with methanol M for the hours need for stimulation of the active
well.
[0084] Preferably, a source of methanol M in tank 60 initially
comprises 100% methanol to permit dilution by the water-based
fluids returned to the tank 60 over a series of flushing
operations, and is maintained at a concentration of about 40%
methanol and preferably above 50% methanol when ambient
temperatures are -25.degree. C. or below.
[0085] Preferably, before methanol flushing operations begin,
sand-laden frac fluid is flushed out of the various supply lines
with sand-free frac fluid, otherwise sand may be carried into the
methanol tank 60 along with the flushed frac fluid. Tank 60 can be
fit with a screen 63 to filter out solids entrained in the methanol
M as the fluid is being pumped out, a sump 61 for allowing finer
particulates to settle therein, or both. Additionally, methanol M
can be drawn from a point in the tank 60 high enough such that
solids settled in the sump 61 will not be pumped to the manifold 10
or components downstream. The tank 60 can be cleaned to remove
solids on a regular basis, for example at the same time the
methanol M is replenished.
[0086] Methanol pump 62 or pumps can be conventional, such as an
impeller pump capable of flowing methanol M at a rate of 100
gallons/min at about 100 psig.
[0087] As one skilled in the art would understand, multiple
manifolds 10 can be used in conjunction in order to service more
wells W. Fluid lines used for the methanol flushing system can be
hydraulic hoses rated for 200-300 psi, with the view of being
durable and easy to move.
Swivel Joint
[0088] Flanged swivel joints 70 can be employed in the system at
various locations along the fracturing lines 21 connecting the
manifold 10 and the fracturing stacks 20. Such flanged swivels 70
further mitigate leaks, ingestion of seals and localized velocity
increases, as sections of reduced bore diameter present in
conventional swivel joints having wing-union connections are
absent. As shown in FIG. 9, the swivel comprises two 90 degrees
sections, each section having a distal end terminating at a
circumferential distal swivel and a flange, and the proximal ends
connected at a proximal swivel for providing a U-shaped fitting
infinitely rotatable 360 degrees at the proximal swivel. The swivel
can be U-shaped with the distal flanges parallel and aligned in the
same plane, through 90 degrees with the flanges at 90 degrees to
one another, and rotatable 180 of the 360 degrees to form an
S-shape with the flanges parallel, the planes of which are
spaced.
[0089] With reference to FIGS. 10A to 12, herein, embodiments of a
flanged swivel joint 70, such as that of FIG. 9, provide a strong,
safe and easily configured system for connection between a manifold
10 and a fracturing stack 20. Swivel joint 70 has flanged
connections 72 at both ends for connection to various components
and connection lines such as fracturing lines 21. By eliminating
the unreliable and weak wing union connections of prior art swivel
joints, as shown in the prior art swivel of FIG. 8, fittings can be
specified and bore diameters can be strategically matched or varied
relative to the bore diameters of upstream and downstream piping
for reducing or maintaining local fluid velocities and avoiding
resultant erosion hot spots. The use of flanged connections 72 also
allow for larger inner bore diameters while maintaining similar
outer diameter as the inlets to the fracturing stacks 20. In the
prior wing union case a reduction of inner bore diameter is
required near the connecting ends to accommodate the wing. The
relatively increased bore diameter of the flanged swivel 70 allows
a lower flow velocity to achieve the same rate of flow.
[0090] For example, the inside diameter of a prior art nominal 4''
inner-diameter Weco 1502 swivel joint has an inner-diameter of
about 3.25 or 3.5'' near the connecting ends, which allows a 6
m.sup.3/min flow rate at 52 fps. However, a same-diameter nominal
4'' flanged swivel joint 70, with the larger inside diameter, is
able to maintain the same flow rate at a velocity of 40 fps
throughout the joint, with no local velocity increases at the
connecting ends. Increased capacity is available, while suffering
the same erosive rate as the lower flow rate of the conventional
swivels. Velocity in the flanged joint 70 can be increased to 52
fps to achieve a flow rate of 7.75 m.sup.3/min. The flanged swivel
joint 70 is also easier to secure to connected components, as no
hammering is required, and alignment with components can be
achieved passively by swivel rotation while the flanges are cinched
square to the connecting flange.
[0091] The flanged swivels 70 are manufactured with large enough
bore diameters to maintain low flow velocity (preferably less than
50 feet per second) as the typical sand laden fracturing fluids F
are pumped therethrough at high rates and for periods of time.
[0092] One or more swivel joints 70 can be implemented at each end
of the connection between the fracturing stack 20 and manifold 10
to allow the connection line 21 to move in all directions and
accommodate line jack movement and vibration for reducing
introduced stresses on the substantially rigid fracturing stack 20
and connections including the connection lines 21 to the fixed
manifold 10. Movement is accommodated by providing freedom of
movement between the manifold and the fracturing stack 20
[0093] The flanged swivels 70 are connected to a block face or
other flange of the conventional equipment, utilizing a
conventional ring seal 74, such as a stainless steel ring gasket,
that is much stronger and more reliable than wing union seals.
[0094] The flange connections 72 enable ease of installation with
the connection line 21 and/or other components, even with initial
misalignments, as the flanged connection 72 can cinched up with one
or more bolts while the swivel 70 adjusts to force the line 21 into
proper alignment. The stronger and leak-proof connections 72 enable
providing connections of line 21 in combinations and arrangements
including at least one swivel 70 at each end of the long line joint
between the manifold 10 and fracturing stack 20.
[0095] Further, the security of the flanged connection 72 enables
limiting wing swivel to a single swivel connection 70, additional
degrees of freedom being provided by bolting flange-to-flange
another intermediate swivel 70 for maximum angular flexibility.
[0096] As shown in FIGS. 9, 10A and 10B, for example a three-way
swivel 70a could mount between an elevated fracturing stack 20 and
fracturing line connection 21 which extends to the manifold 10
typically at ground level. A second swivel 70b can be located at
the end of the long joint of line 21, on the ground, adjacent the
manifold 10, and a third swivel 70c can be located adjacent the
manifold fluid outlet 40. The two joints 70b and 70c enable free
longitudinal growth of line 21.
[0097] In a further embodiment, as shown in FIG. 11, additional
swivel joints 70d can be combined together with the fracturing
stack swivel 70a, and the fluid outlet swivels 70b,70c, to provide
additional angular degree of freedom to fracturing line 21.
[0098] As a result of the high flexibility of the high pressure
connections using the high-flow flanges swivels, a safe reliable
fracturing system ins achieved that that includes higher
reliability, longer periods between maintenance cycles and the
ability to absorb jack and vibration.
* * * * *