U.S. patent application number 14/007845 was filed with the patent office on 2014-03-20 for system and method for reducing pressure fluctuations in an oilfield pumping system.
This patent application is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. The applicant listed for this patent is Rod Shampine. Invention is credited to Rod Shampine.
Application Number | 20140076577 14/007845 |
Document ID | / |
Family ID | 46932348 |
Filed Date | 2014-03-20 |
United States Patent
Application |
20140076577 |
Kind Code |
A1 |
Shampine; Rod |
March 20, 2014 |
SYSTEM AND METHOD FOR REDUCING PRESSURE FLUCTUATIONS IN AN OILFIELD
PUMPING SYSTEM
Abstract
Presented herein is a system, method, and assembly for reducing
pressure fluctuations in an oilfield pumping system. The pressure
fluctuation dampening assembly includes a junction, a dampening
chamber, and a supply of a compressible medium. The compressible
medium is supplied so as to form an interface between the fluid and
the compressible medium such that a pressure fluctuation of fluid
passing through the junction is reduced.
Inventors: |
Shampine; Rod; (Houston,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shampine; Rod |
Houston |
TX |
US |
|
|
Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION
Sugar Land
TX
|
Family ID: |
46932348 |
Appl. No.: |
14/007845 |
Filed: |
March 29, 2012 |
PCT Filed: |
March 29, 2012 |
PCT NO: |
PCT/US12/31323 |
371 Date: |
December 3, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61468867 |
Mar 29, 2011 |
|
|
|
Current U.S.
Class: |
166/373 ;
166/91.1 |
Current CPC
Class: |
F16L 55/041 20130101;
E21B 43/12 20130101; F16L 55/05 20130101 |
Class at
Publication: |
166/373 ;
166/91.1 |
International
Class: |
E21B 43/12 20060101
E21B043/12 |
Claims
1. A system for reducing pressure fluctuations, comprising: at
least one pump directing fluid through a junction having a first
port, a second port, and a third port; a chamber coupled to the
third port of the junction; and a supply of a compressible medium
in fluid communication with the chamber; wherein the supply of
compressible medium provides the compressible medium to the chamber
so as to form an interface between the fluid and the compressible
medium such that a pressure fluctuation of fluid passing through
the junction is reduced.
2. The system of claim 1, wherein the chamber is oriented so as to
trap gas.
3. The system of claim 2, wherein the chamber is substantially
vertical.
4. The system of claim 1, wherein the interface is movable in
response to the pressure fluctuation of the fluid.
5. The system of claim 1, wherein the first port is in
communication with a fluid end of a pump, and the second port is in
communication with a wellbore.
6. The system of claim 1, wherein the junction is a
tee-junction.
7. The system of claim 1, wherein a sonic choke is couple to at
least one of the first port and the second port.
8. The system of claim 1, wherein the pump is a positive
displacement pump.
9. The system of claim 1, wherein the fluid is an oilfield fluid
used in an oilfield operation selected from the group consisting of
hydraulic fracturing, cementing, drilling, testing, measuring,
stimulating, working over, completing, and producing.
10. The system of claim 1, wherein the junction is a portion of the
at least one pump.
11. The system of claim 1, wherein the first port and the second
port are substantially aligned.
12. The system of claim 1, wherein the first port and the second
port are substantially nonaligned.
13. The system of claim 1, wherein a pressure in the junction is at
least 10,000 PSI.
14. The system of claim 1, wherein a pressure in the junction is at
least 15,000 PSI.
15. A method for dampening pressure fluctuations in a fluid stream,
the method comprising: providing a junction having a first port, a
second port, and a third port; connecting the first port to at
least one pump, and the second port to a wellbore; connecting a
chamber to the third port of the junction; directing a fluid
through the junction; supplying a compressible medium to the
chamber; and forming an interface between the fluid and the
compressible medium so as to reduce a pressure fluctuation in the
fluid.
16. The method of claim 15, wherein the fluid is an oilfield fluid
used in an oilfield operation selected from the group consisting of
hydraulic fracturing, cementing, drilling, testing, measuring,
stimulating, working over, completing, and producing.
17. The method of claim 15, wherein the compressible medium is
supplied upstream of the junction.
18. A pressure fluctuation dampening assembly, comprising: a
junction having a first port, a second port, and a third port; a
chamber coupled to the third port of the junction, and oriented so
as to trap gas; and a gas supply tank in fluid communication with
the chamber so as to provide gas to the chamber; wherein gas
supplied to the chamber forms an interface between a fluid passing
through the junction and the gas such that a pressure fluctuation
of the fluid is reduced.
19. The assembly of claim 18, wherein the first port and the second
port are substantially aligned.
20. The assembly of claim 18, wherein the first port and the second
port are substantially nonaligned.
21. The assembly of claim 18, wherein the junction is a
tee-junction.
Description
BACKGROUND
[0001] The statements made herein merely provide information
related to the present disclosure and may not constitute prior art,
and may describe some embodiments illustrating the invention.
[0002] Large oilfield operations generally involve any of a variety
of positive displacement or centrifugal pumps. Such pumps may be
employed in applications for accessing underground hydrocarbon
reservoirs. For example, positive displacement pumps are often
employed in large scale high pressure applications directed at a
borehole leading to a hydrocarbon reservoir. Such applications may
include cementing, coiled tubing, water jet cutting, or hydraulic
fracturing of underground rock.
[0003] A positive displacement pump such as those described above
may be a fairly massive piece of equipment with associated engine,
transmission, crankshaft and other parts, operating at between
about 200 Hp and about 4,000 Hp. An example of a positive
displacement pump, such as triplex or quintuplex pump, is disclosed
in commonly assigned PCT Publication No. WO2011/027274, the entire
contents of which are hereby incorporated by reference into the
current disclosure. A large plunger is driven by the crankshaft
toward and away from a chamber in the pump to dramatically affect a
high or low pressure thereat. This makes it a good choice for high
pressure applications. Indeed, where fluid pressure exceeding a few
thousand pounds per square inch (PSI) is to be generated, a
positive displacement pump is generally employed. Hydraulic
fracturing of underground rock, for example, often takes place at
pressures of 6,000 to 20,000 PSI or more to direct an abrasive
containing fluid through a borehole such as that noted above to
release oil and gas from rock pores for extraction.
[0004] Whether a positive displacement pump as described above, a
centrifugal pump, or some other form of pump for large scale or
ongoing operations, one frequently encounters wellbores and piping
rig ups where significant pressure fluctuations/perturbations are
created. These perturbations can lead to violent tremors of
oilfield equipment, such as trucks and treating line/iron, which
potentially cause damage to equipment, failed jobs, and personal
injuries, etc. Such pressure fluctuations/oscillations may be
caused by a variety of phenomena, for example, resonances in the
pumps, failed valves, or obstructions (e.g., rocks) in a
plunger/valve. These pressure fluctuations produced by pumps can
also interfere with or obscure measurements that are important to
the course of a job.
[0005] In the field of mud pumps, for example, gas filled rubber
bladders are often applied to both the suction and discharge sides
of the mud pumps to reduce the large pressure fluctuations
associated with duplex single and double acting pumps. While
effective, these dampers are impractical to apply to services where
significant abrasives, high pressure, and aggressive fluids are
employed. Among other possible problems, the bladders of these
systems are subject to deterioration when in contact with abrasive
fluids at high, fluctuating pressures. One example of a service
where significant abrasive, high pressure, and aggressive fluids
are employed may be hydraulic fracturing operations or other
portable oilfield pumping operations where positive displacement
pumps, such as triplex pumps are commonly used. The abrasive nature
of fracturing fluid is not only effective in breaking up
underground rock, but would also tend to wear out an elastomeric
bladder used for dampening. Moreover, the commercially available
dampers are only rated up to 10,000 PSI, and would fail rapidly
when exposed to the complex acids and hydrocarbons employed in
fracturing. Constructing a dampening device for a 15,000 PSI rating
would entail radical increases in wall thickness, costly material,
and the like. Further, these systems are very limited in the range
of gas pre-charge to pumping pressure that they can support. For
example, a 3:1 ratio between the pre-charge pressure and the
maximum reliable operating pressure represents a desirable ratio.
In this case, a damper that will be pressure tested to 15,000 PSI
must not be charged to less than 5,000 PSI. With this pre-charge,
the damper will have no effect at all below .sub.5,000 PSI. The
optimum charge for damping is around 80% of the operating pressure
for a bladder type damper. Thus, such a system has a significant
lower limitation and also will need to be adjusted from job to job,
rather than set up and left in service.
[0006] As such, it would be desirable to have a system and method
for suppressing resonances and pressure fluctuations in operations
where significant abrasives, high pressures, and aggressive fluids
are employed.
SUMMARY
[0007] This summary is provided to introduce a selection of
concepts that are further described below in the detailed
description. This summary is not intended to identify key or
essential features of the claimed subject matter, nor is it
intended to be used as an aid in limiting the scope of the claimed
subject matter.
[0008] Embodiments of the present disclosure provide a pressure
dampening apparatus and method which can dampen pressure
perturbations in an oilfield pumping system. In view of the
foregoing disadvantages inherent in the known types of methods and
systems present in the prior art, certain embodiments disclosed
herein address the above and other problems by providing a pressure
dampening apparatus and method that does not require the use of a
bladder, can be self-adjusting for the optimum operating
conditions, and is adapted to be resistant to oilfield chemicals
and fluids delivered at high, fluctuating pressures.
[0009] In at least one aspect, embodiments of the disclosure relate
to a system for reducing pressure fluctuations, comprising: at
least one pump directing fluid through a junction having a first
port, a second port, and a third port; a chamber coupled to the
third port of the junction; and a supply of a compressible medium
in fluid communication with the chamber; wherein the supply of
compressible medium provides the compressible medium to the chamber
so as to form an interface between the fluid and the compressible
medium such that a pressure fluctuation of fluid passing through
the junction is reduced.
[0010] In another aspect, embodiments of the disclosure relate to a
method for dampening pressure fluctuations in a fluid stream, the
method comprising: providing a junction having a first port, a
second port, and a third port; connecting the first port to at
least one pump, and the second port to a wellbore; connecting a
chamber to the third port of the junction; directing a fluid
through the junction; supplying a compressible medium to the
chamber; and forming an interface between the fluid and the
compressible medium so as to reduce a pressure fluctuation in the
fluid.
[0011] In yet another aspect, embodiments of the disclosure relate
to a pressure fluctuation dampening assembly, comprising: a
junction having a first port, a second port, and a third port; a
chamber coupled to the third port of the junction, and oriented so
as to trap gas; and a gas supply tank in fluid communication with
the chamber so as to provide gas to the chamber; wherein gas
supplied to the chamber forms an interface between a fluid passing
through the junction and the gas such that a pressure fluctuation
of the fluid is reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Embodiments of a system and method for reducing pressure
fluctuations in an oilfield pumping system are described with
reference to the following figures. The same numbers are used
throughout the figures to reference like features and components.
Implementations of various technologies will hereafter be described
with reference to the accompanying drawings. It should be
understood, however, that the accompanying drawings illustrate only
the various implementations described herein and are not meant to
limit the scope of various technologies described herein.
[0013] FIG. 1 illustrates a simplified, schematic view of an
oilfield pumping system in accordance with implementations of
various technologies and techniques described herein.
[0014] FIGS. 2A and 2B illustrate schematic views, partially in
cross-section, of a junction in fluid communication with the
oilfield pumping system in accordance with implementations of
various technologies and techniques described herein.
[0015] FIGS. 3-6 illustrate schematic variations of the oilfield
pumping system in accordance with implementations of various
technologies and techniques described herein.
[0016] FIGS. 7-8 illustrate schematic variations of the oilfield
pumping system integrated with at least one pump in accordance with
implementations of various technologies and techniques described
herein.
[0017] FIG. 9 illustrates a simplified, schematic view of another
oilfield pumping system in accordance with implementations of
various technologies and techniques described herein.
[0018] FIG. 10 illustrates a simplified, schematic view of yet
another oilfield pumping system in accordance with implementations
of various technologies and techniques described herein.
[0019] FIG. 11 illustrates a schematic view of another oilfield
pumping system having multiple pumps in accordance with
implementations of various technologies and techniques described
herein.
[0020] FIGS. 12-13 illustrate schematic variations of the oilfield
pumping system having multiple dampening chambers in accordance
with implementations of various technologies and techniques
described herein.
DETAILED DESCRIPTION
[0021] The discussion below is directed to certain specific
implementations. It is to be understood that the discussion below
is only for the purpose of enabling a person with ordinary skill in
the art to make and use any subject matter defined now or later by
the patent "claims" found in any issued patent herein.
[0022] FIG. 1 illustrates a simplified, schematic view of an
oilfield pumping system 10 for directing fluid to a wellbore 42.
Fluid, which may carry oilfield material such as proppant and
proppant additives, is pressurized by one or more pumps 12 and
directed through a treating line 14 to a pressure dampening device
20.
[0023] Pump(s) 12 may include a variety of pumps known in the art,
such as positive displacement pumps, crankshaft driven pumps,
hydraulic pressure driven pumps, centrifugal pumps, and the like.
Pressurizing the fluid with pump(s) 12 inherently creates
perturbations or fluctuations in the fluid.
[0024] The pressure fluctuation dampening assembly, or pressure
dampening device 20, is adapted to dampen the perturbations or
fluctuations of the fluid. The pressure dampening device 20
comprises a conduit/junction 22, a dampening chamber 16, and a
fluid/gas supply system 30. The junction 22 has a first port 23, a
second port 24 and a third port 25, shown generally in FIG. 1 as a
"tee," but as will be seen hereinafter may comprise various shapes
and sizes. The first port 23, acting as an inlet section of the
junction 22 receives fluid from the pump(s) 12 via the treating
line 14. The second port 24, acting as an outlet section of the
junction 22 is coupled to a treating line 18 for directing fluid to
a wellhead 40 or any other means for delivering treatment, such as
a cement head or a coiled tubing reel. The third port 25 of the
junction 22 leading in a generally upward/vertical direction is
coupled to the dampening chamber 16, which in function acts to
reduce the pressure fluctuations of the fluid in coordination with
the other elements of the pressure dampening device 20, but in
construction the chamber 16 may be a treating line having a cap 36
at the end. The cap 36 may function as a connection between the
chamber 16 and the fluid/gas supply system 30.
[0025] The fluid/gas supply system 30 is adapted to supply a
compressible medium to the dampening chamber 16 in accordance with
the operating conditions (i.e., fluid flow rate, pressure
conditions, fluid type, etc.). The compressible medium supplied by
the fluid/gas supply system is referred to herein as simply `gas`
as a matter of conciseness, but should be understood to also
include liquids that are more compressible than the fluid being
pumped. Examples of the compressible medium may include nitrogen,
argon, air, ethyl alcohol, carbon disulfide, ethyl ether and the
like. The fluid/gas supply system 30 comprises a gas pump 32 to
pressurize gas supplied by a gas supply tank 34. Gas may also be
supplied to the pressure dampening device 20 by various means. For
example, gas may be supplied via a Dewar containing liquefied gas
(e.g. liquid nitrogen); moreover, a nitrogen-rich gas may be
supplied via a separating membrane in fluid communication with a
compressed air tank. A valve 31 may be used as part of the
fluid/gas supply system 30 to control the amount of gas supplied by
the gas supply tank 34. The fluid/gas supply system 30 may further
comprise at least one check valve 38 along a gas supply line 33 so
as to ensure that the fluid does not enter the gas pump 32. A bleed
valve 37 may also be fitted to the cap 36 to drain fluid and/or
release pressure built up in the chamber 16. The bleed valve 37 may
be located elsewhere in the system, and should not be limited to
the location shown. It should be noted that while the fluid/gas
supply system 30 is shown to be coupled to the dampening chamber
16, the fluid/gas supply system 30 may also be coupled upstream of
the junction 22 so that gas travel along with the fluid and be
trapped in the dampening chamber 16. It should also be noted that
the fluid/gas supply system 30 may include boosting means to
sufficiently pressurize the gas into the dampening chamber 16.
[0026] A sonic choke 50 may optionally be located before or after
(the latter is shown) the junction 22, or even in both locations.
The sonic choke 50, which will be described in more detail
hereinafter with reference to FIG. 2, provides additional
resistance and reflection to pressure fluctuations in the
fluid.
[0027] FIG. 2A illustrates a schematic view, partially in
cross-section, of the junction 22 of FIG. 1 in fluid communication
with the oilfield pumping system 10. Gas is introduced into the
dampening chamber 16 to create a gas filled space, referenced as
19, and a gas to liquid interface 17. As pressure and flow
fluctuations pass into the junction 22, the fluctuations produce
motions of the interface 17, substantially reducing the magnitude
of the fluctuations at the outlet 24. The interface 17 may
optionally include an object/device, such as a floating mass or
Wier-type device, so as to prevent splashing of the fluid into the
chamber 16 and/or lower the resonant frequency of the system. The
object/device located at the interface 17 may also be tagged so as
to measure the volume of gas/liquid in the chamber 16.
[0028] Any solids, for example oilfield material, in the fluid 15
flowing from the pump(s) 12 may become entrained in the dampening
chamber 16. Due in part to the orientation of the dampening chamber
16, gravity will assist any solids in falling out of the dampening
chamber 16 and preventing it from being blocked. However, it should
be noted that the chamber 16 may be angled in a variety of
directions so as to be oriented to trap gas and thereby provide a
dampening effect on the pressure fluctuations of the fluid.
[0029] The sonic choke 50 is shown in more detail here in FIG. 2A
connected between the second port 24 of the junction 22 and the
treating line 18 leading to a wellbore 42. The sonic choke 50
functions herein as a differential pressure conduit and may
comprise a Venturi having a converging, diverging and throat
section (shown herein), an orifice plate, or the like for providing
additional reduction to the pressure fluctuations in the fluid
15.
[0030] In operating the oilfield pumping system 10 having a
pressure dampening device 20, the chamber 16 may be charged using
the gas pump 32 as soon as the system pressure has been brought up
near the operating pressure. The chamber 16 can be re-charged at
any time the treating pressure is reduced significantly and then
raised again. Alternatively, a flow of gas into the chamber 16 may
be maintained at all times, or during times where the overall
pressure is changing significantly. As the interface 17 moves up
and down, excess gas may exit the chamber 16 into the junction 22
and flow downstream eventually into the wellbore 42.
[0031] For example, if the nominal treating pressure is 6,000 PSI,
the pressure fluctuations of the fluid 15 may vary between 6,500
PSI and 5,500 PSI. At 6,500 PSI, the gas 19 in the chamber 16 is
compressed, moving the interface 17 towards the cap 36, thereby
reducing the pressure of the fluid 15 at the outlet 24. Whereas, at
5,500 PSI, for example, the gas 19 in the chamber 16 may compress
the fluid, moving the interface 17 towards the junction 22, and
possibly releasing gas into the fluid stream 13.
[0032] FIG. 2B illustrates a schematic view, partially in
cross-section, of a variation of the junction 22, wherein the
junction 22 comprises a cavity 26 for collecting a certain amount
of solids 13 contained in the fluid so as to act as a barrier
against any jetting action created by movement of the interface 17,
and further reduce the pressure fluctuation of the fluid 15. The
cavity 26 may also lengthen the overall life of the junction 22 and
reduce washout, or erosion of the junction 22.
[0033] FIG. 3 illustrates a schematic view of another embodiment of
the oilfield pumping system 10 wherein the junction 22 is formed as
a lateral so that the flow can be substantially aligned with the
direction of the motion of the gas to liquid interface in the
chamber 16, thereby reducing the pressure fluctuations of the
fluid.
[0034] FIG. 4 illustrates a schematic view of yet another
embodiment of the oilfield pumping system 10 wherein the junction
22 is formed as a double lateral wherein a cavity section 26
opposes the pressure dampening chamber 16 to further reduce
fluctuations.
[0035] FIG. 5 illustrates a schematic view of another embodiment of
the oilfield pumping system 10 wherein the junction 22 is formed as
a lateral so that the flow is aligned with the direction of the
motion of the gas to liquid interface in the chamber 16.
[0036] FIG. 6 illustrates a schematic view of yet another
embodiment of the oilfield pumping system 10 wherein the junction
22 is formed as a reversal chamber to reduce erosion due to the
change in direction of flow.
[0037] FIG. 7 illustrates a schematic view of an embodiment of the
oilfield pumping system 10 wherein the pressure dampening device 20
is integrated directly to the pump(s) 12. In operation, fluid
enters the pump(s) 12 via a suction header 62. A suction damper 64
may be integrated into the suction header 62 to smooth out the
fluctuations of the flow on the suction side. A pump head 66 may
contain valves and a plunger system for delivering fluid at a high
pressure (higher than the pressure of the fluid entering the
suction header 62) out of a discharge port, referenced herein as
14. The pressure dampening device 20 is fitted to the discharge
port 14 so as to reduce the pressure fluctuations of the fluid
discharged from the pump(s) 12. As illustrated by the present
embodiment, the pressure dampening device 20 may be integrated into
multiple locations along the oilfield pumping system 10. While not
shown, it should be understood that the pressure dampening device
20 may be integrated into the wellhead 40, wherein the wellhead 40
is adapted to form the junction 22 coupled to the dampening chamber
16 and gas supply system 30.
[0038] FIG. 8 illustrates a schematic view of another embodiment of
the oilfield pumping system 10 wherein the pressure dampening
device 20 is integrated directly to the pump(s) 12. The dampening
chambers 16a/16b/16c are coupled to the discharge covers
68a/68b/68c on the pump head 66. Using more than one chamber 16
reduces the length of the chamber 16 required due to a distribution
of pressure fluctuation across multiple chambers 16a/16b/16c.
Moreover, locating the pressure dampening device 20 closer to the
source of the fluctuations may provide an additional benefit in
reducing the overall pressure fluctuations of the system 10.
[0039] FIG. 9 illustrates a schematic view of yet another
embodiment of the oilfield pumping system 10 wherein the chamber 16
is substantially larger in diameter than the treating line. The
pressure dampening device 20 comprises an adapter 27 coupled to the
third port 25 so as to allow the installation of the chamber 16
that is substantially larger in diameter than the treating
line.
[0040] FIG. 10 illustrates a simplified, schematic view of an
oilfield pumping system 10 wherein the sonic choke 50 is placed
upstream of the junction 22 so as to dampen the pressure
fluctuations of the fluid prior to forming an interface between the
fluid and the gas.
[0041] FIG. 11 illustrates a schematic view of another embodiment
of the oilfield pumping system 10 wherein two groups of pumps
direct pressurized fluid through a pressure dampening device 20
having multiple inlets 23a/23b and outlets 24c/24d. One or more
sonic chokes 50a/50b/50c/50d may be place on the inlets 23a/23b and
outlets 24c/24d to further dampen the pressure fluctuations.
[0042] FIGS. 12 and 13 illustrate schematic views of embodiments of
the oilfield pumping system 10 depicting a pressure dampening
device 20 having multiple dampening chambers 16a/16b/16c coupled to
the third ports 25a/25b/25c of the junctions 22a/22b/22c. Similar
to the function of the arrangement in FIG. 8, the array of chambers
16a/16b/16c may be employed to reduce the length of the chambers
16a/16b/16c. FIG. 12 shows that the gas supply system 30 may be
connected to each chamber 16a/16b/16c with a common gas supply line
33. Whereas, FIG. 13 shows that the gas supply system 30 may be
connected to any one of the chambers (shown here as 16a), upstream
of the junctions 22b and 22c such that gas fed into chamber 16a
will be carried by the fluid into the subsequent chambers 16b and
16c. Moreover, shown in FIG. 13 is a change in elevation of the
junctions 22a/22b/22c that may aid in distribution of the gas in
the chambers 16a/16b/16c.
[0043] The preceding description has been presented with reference
to some embodiments. Persons skilled in the art and technology to
which this disclosure pertains will appreciate that alterations and
changes in the described structures and methods of operation can be
practiced without meaningfully departing from the principle, and
scope of this application. For example, while the junction 22 is
shown as having ports and connections with treating line, it should
be understood that the junction may be integrated with flow lines
to be one piece. In addition, the gas supply system Accordingly,
the foregoing description should not be read as pertaining only to
the precise structures described and shown in the accompanying
drawings, but rather should be read as consistent with and as
support for the following claims, which are to have their fullest
and fairest scope.
* * * * *