U.S. patent application number 15/099023 was filed with the patent office on 2017-01-12 for modular configurable compression systems and methods.
The applicant listed for this patent is Dag O. CALAFELL. Invention is credited to Dag O. CALAFELL.
Application Number | 20170009774 15/099023 |
Document ID | / |
Family ID | 55806872 |
Filed Date | 2017-01-12 |
United States Patent
Application |
20170009774 |
Kind Code |
A1 |
CALAFELL; Dag O. |
January 12, 2017 |
Modular Configurable Compression Systems and Methods
Abstract
Systems, methods and apparatuses for matching an operation range
to a reservoir depletion condition are disclosed herein. An
embodiment provides a modular compression system for matching an
operation range to a reservoir depletion condition. The modular
compression system includes a compressor arranged to compress a
gas, a motor or other driver coupled to the compressor and
configured to provide power to the compressor, and a pressure
casing surrounding the compressor and the motor. The modular
compression system further includes a modular motor assembly
configured to be selectively attachable and mechanically coupled to
the compressor and the pressure casing. The modular motor assembly
is arranged to provide supplemental power to the compressor to
change the capacity of the modular compression system to compress
the gas.
Inventors: |
CALAFELL; Dag O.; (Katy,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CALAFELL; Dag O. |
Katy |
TX |
US |
|
|
Family ID: |
55806872 |
Appl. No.: |
15/099023 |
Filed: |
April 14, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62190095 |
Jul 8, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 25/04 20130101;
F04D 25/022 20130101; F04D 29/584 20130101; F04D 25/0606 20130101;
F04D 25/06 20130101 |
International
Class: |
F04D 25/06 20060101
F04D025/06; F04D 29/58 20060101 F04D029/58 |
Claims
1. A modular compression system comprising: a compressor arranged
to compress a gas; a driving element coupled to the compressor and
configured to provide power to the compressor; a pressure casing
surrounding the compressor and the driving element; and a modular
motor assembly configured to be selectively attachable and coupled
to the compressor and the pressure casing, the modular motor being
arranged to provide supplemental power to the compressor to change
the capacity of the modular compression system to compress the
gas.
2. The modular compression system of claim 1, further comprising: a
base plate; and at least one support member connected between the
pressure casing and the base plate configured to support the
compressor, the driving element, and the modular motor.
3. The modular compression system of claim 2, further comprising: a
first flange on the pressure casing; a second flange on the modular
motor, wherein the first flange is connected to the second flange,
and wherein the modular motor assembly is not in contact with any
support members connected to the base plate.
4. The modular compression system of claim 1, wherein the modular
motor assembly is coupled to the driving element in a series
driving configuration or a tandem configuration.
5. The modular compression system of claim 1, further comprising a
cooling water jacket on the periphery of the pressure casing.
6. The modular compression system of claim 1, further comprising: a
modular separator having a first inlet configured to receive a
fluid mixture and an outlet configured to produce a gas, and
wherein the outlet is coupled to the compressor at a second inlet
of the compressor.
7. The modular compression system of claim 6, further comprising: a
modular heat exchanger coupled to an end of the modular separator,
the modular separator coupled to an end of the compressor.
8. The modular compression system of claim 1, further comprising a
modular compression assembly drivably connected to both the driving
element and the modular motor assembly.
9. The modular compression system of claim 8, wherein the modular
compression system is configured to divide the input gas stream
into a first gas stream and a second gas stream, and wherein the
modular compression system is configured to compress the first gas
stream and the second gas stream in parallel.
10. The modular compression system of claim 1, wherein the driving
element is an electric motor.
11. The modular compression system of claim 1, wherein the driving
element is a turbine.
12. A method for processing a gas stream using a modular
compression system, wherein the modular compression system
comprises a driving element mechanically coupled to a compressor by
at least one shaft, and wherein the modular compression system
further comprises a pressure casing surrounding the driving element
and the compressor, the method comprising: removing a portion of
the pressure casing to allow a modular motor assembly to couple to
the compression system; and connecting the modular motor to the
compression system to boost drive power supplied to the
compressor.
13. The method of claim 12, further comprising: measuring an inlet
gas pressure; and determining that the inlet gas pressure is less
than a threshold, wherein the removing and the connecting are
performed in response to the determining that the inlet gas
pressure is less than a threshold.
14. The method of claim 13, wherein the method further comprises:
determining that the inlet gas pressure is less than a second
threshold; in response to the determining that the inlet gas
pressure is less than the second threshold, connecting a modular
compressor assembly to the modular motor to provide additional
compression to the gas stream.
15. The method of claim 12, wherein the modular motor connects to
the compressor to drive the compressor in a tandem motor
configuration or a drive-through configuration.
16. The method of claim 13, wherein the method further comprises:
determining that the inlet gas pressure is less than a second
threshold; in response to the determining that the inlet gas
pressure is less than the second threshold: opening the pressure
casing; removing a component, wherein the component comprises
either the compressor or the driving element; replacing the
component with a second component of increased capacity to provide
greater compression to the gas stream; and closing the pressure
casing.
17. The method of claim 12, wherein the driving element is one of
an electric motor and a turbine.
18. A modular apparatus comprising: a modular motor assembly
configured to selectively attach to and provide supplemental power
to a compression system, wherein the compression system comprises a
first motor, the modular motor assembly comprising: a shaft
configured to couple to the compression system; a second motor
coupled the shaft and configured to provide the supplemental power;
and an interface structure configured to be selectively affixed to
the compression system to attach the modular motor assembly to the
compression system.
19. The modular apparatus of claim 18, wherein the modular motor
assembly further comprises a partition, and wherein the shaft
extends beyond the partition and is mechanically coupled to the
compression system.
20. The modular apparatus of claim 18, further comprising a
compression system, wherein the compression system further
comprises a first compressor and a second shaft, and wherein the
shaft is mechanically coupled to the second shaft to assist with
driving the first compressor.
21. The modular apparatus of claim 20, further comprising a modular
compressor assembly selectively and mechanically coupled to the
compression system, wherein the modular compressor assembly
comprises a second compressor.
22. The modular apparatus of claim 21, wherein the first motor and
the second motor are configured to transfer mechanical power to the
first compressor and the second compressor.
23. The modular apparatus of claim 19, wherein the modular motor
assembly further comprises: a pressure casing; and a flange
surrounding a circumference of the pressure casing, wherein the
flange is configured to couple to the interface structure of the
modular motor assembly, the flange being configured to support the
weight of the modular motor assembly.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority benefit of U.S. patent
application Ser. No. 62/190,095 filed Jul. 8, 2015 entitled MODULAR
CONFIGURABLE COMPRESSION SYSTEMS AND METHODS, the entirety of which
is incorporated by reference herein.
FIELD OF THE INVENTION
[0002] This disclosure relates to compression systems and methods
for processing gas or liquid streams. More particularly, this
disclosure relates to configuring and reconfiguring compression
systems using modular components, such as modular motor assemblies
and modular compression assemblies, to adjust compression systems
to process gas streams as compression requirements change, for
example, in oil and gas production as hydrocarbon reservoirs are
depleted and gas pressure decreases, or injection requirements
change. Compression systems may further include modular turbines.
This disclosure similarly relates to configuring and reconfiguring
pumps using modular components.
BACKGROUND
[0003] This section is intended to introduce various aspects of the
art, which may be associated with exemplary embodiments of the
present techniques. This discussion is believed to assist in
providing a framework to facilitate a better understanding of
particular aspects of the present techniques. Accordingly, it
should be understood that this section should be read in this
light, and not necessarily as admissions of prior art.
[0004] Centrifugal compressors are applied in oil and gas
production to compress wellhead gases for transportation or
treatment. Compressors increase gas pressure from a low suction
condition to a higher discharge pressure. Some conventional
compressors include one or more centrifugal impellers attached to a
shaft. The impellers and shaft are rotated by a driver that
provides power to compress the gas and overcome thermodynamic and
mechanical inefficiencies. Conventional compressor design and
staging typically results in fixed geometries that create a
restricted flow range and a limited pressure rise.
[0005] Staging includes selection of various compressor parameters,
such as the impeller geometry (e.g., the number and shape of the
passages), the number of impellers, gas diffusion passages after
each impeller, the speed of shaft rotation, and any cooling
requirements. Staging options can be constrained by mechanical and
dynamic considerations, including, as examples, forces exerted on
the impeller, shaft, bearings, and seals that are produced by the
gas compression process or static and dynamic forces.
[0006] Conventional staging selection results in a specific stable
operating range of pressures in which gas will flow from inlet to
outlet. In many scenarios, as the flow decreases the pressure rise
increases. However, if flow rate is too low the gas will stop
flowing. On the other hand, if flow rate is too high the gas will
not be compressed sufficiently and the high mass flow rate may
overload the compressor mechanical design or driver capabilities.
These issues can limit the inlet conditions that any given unit or
specific design can process.
[0007] This characteristic in centrifugal machinery converts high
dynamic forces (impeller rotation combined with impeller outside
diameter) to higher pressures. In some conventional embodiments,
this conversion is performed by imparting energy to the gas
(manifested by the high velocity gas exiting the outside diameter
of the impeller) and then converting it to higher pressures by
reducing the gas velocity through a gas diffusion process.
[0008] A narrow operating flow range is insufficient to meet the
variations in a typical oil and gas production over the entire oil
field life as the oil field matures and declines. Thus, at some
point, if it is desired to keep harvesting a field, changes should
be made to the compressor to accommodate changing field conditions
so the gas can still be produced. Those changes can affect, as
examples, the number of impellers, size of the impellers, physical
size of the compressor casing, and the horsepower requirements from
the installed driver.
[0009] There are various options to respond to the changing field
requirements. Some common conventional options are as follows: (1)
restage the compressor rotor within the compressor casing
dimensional capacity and within the existing driver power
requirements; (2) upgrade the driver horsepower capabilities within
the driver casing capabilities; and/or (3) consider new compressor
or driver sizes and types. Upgrades to the compressor or to the
driver may not be available or sufficient to meet the changed
compression duty. In order to modify or install new compressor
and/or drivers, a substantial amount of production can be lost due
to system downtime. This potential loss enters into decisions
whether to modify, replace, or do-nothing to the compression
system. In some circumstances, the economics of oil and gas
production may preclude any opportunity to rerate, restage,
repower, and/or replace the compression system. In that case, oil
and gas production may cease before a reservoir is fully depleted
due to the limitations of the installed compression equipment.
[0010] FIG. 1 illustrates various representative examples of field
flow rate declines experienced by a given gas reservoir or field.
The x-axis is in units of months, and the y-axis is in units of
thousands of barrels per day (a flow rate). According to FIG. 1, a
given field declines in a gradual manner. The various curves are
examples of flow rate decreases over time, and are intended to be
illustrative and not exhaustive. For example, curve 110 represents
a linear decrease in flow rate, and curves 120, 130, and 140
represent an exponential decrease. Furthermore, flow rate on the
y-axis is a proxy for reservoir pressure. Therefore, the reservoir
pressure typically declines in a like manner.
[0011] As explained above, conventional compression systems are
fixed and can accommodate only small variations in inlet pressure
and discharge pressure. As a result, conventional compression
systems may be sized to accommodate a limited range of pressures
exhibited by a field. Because of the capital costs and lost
production associated with compressor restaging and/or rerates, in
some embodiments, the depletion curve is conventionally divided
into two or more specific pressure regions where compressor
restaging is likely to occur.
[0012] Within each pressure region, the compressor inlet pressure
is typically set at a value lower than the reservoir pressure
(otherwise the gas would not flow from the reservoir to the
compressor), which implies that excess pressure energy of the
reservoir is being throttled at each well. Thus, a compressor
replaces that energy while compressing the gas to an original
design discharge pressure required for the processing or
transporting the gas. A substitution of the existing reservoir
drive pressure with mechanical compression energy is a large
operating cost and a loss of the resource (because the energy
typically comes from consuming a portion of the resource). Thus,
there is a need for compression systems that are able to match
reservoir depletion curves in a more efficient and cost-effective
manner.
SUMMARY
[0013] Modular pressure casings can be interconnected. These
casings can be fitted internally with either a driver, e.g., an
electric motor, or a driven piece of machinery, e.g., compressor or
pump. These internal components can be connected through various
means to deliver power from one or more drivers to one or more
driven machinery elements. External or internal features of these
casings can ensure that the required machinery alignment is
achieved without relying on multiple external support members.
Example configurations consistent with this principle allow for
extending the length of the machinery train via a cantilever
arrangement on both ends of the interconnected modular pressure
casings. Gas passages to convey fluid between/among the modular
casings can be incorporated in the casing. Separation elements,
e.g., in-line or cyclonic separators, and cooling elements can also
form part of the casing in a standardized arrangement. Rerating the
compressor or pump service may be performed in a straightforward
manner by combining the appropriate modular, interchangeable
pressure casings with driver and driven elements.
[0014] An embodiment provides a modular compression system that
includes a compressor arranged to compress a gas, a driving element
coupled to the compressor and configured to provide power to the
compressor, and a pressure casing that surrounds the compressor and
the driving element. The modular compression system further
includes a modular motor assembly configured to be selectively
attachable and coupled to the compressor mechanically or by other
means such as fluid or magnetically, and the pressure casing. The
modular motor assembly is arranged to provide supplemental power to
the compressor to change the capacity of the modular compression
system to compress the gas.
[0015] Another embodiment provides a method for processing a gas
stream using a modular compression system. The modular compression
system includes a driving element mechanically coupled to a
compressor by at least one shaft. The modular compression system
further includes a pressure casing surrounding the driving element
and the compressor. The method includes removing a portion of the
pressure casing to allow a modular motor assembly to couple to the
compression system, and connecting the modular motor to the
compression system to boost drive power supplied to the
compressor.
[0016] Another embodiment provides a modular apparatus. The modular
apparatus includes a modular motor assembly configured to
selectively attach to and provide supplemental power to a
compression system, wherein the compression system includes a first
motor. The modular motor assembly includes a shaft configured to
couple to the compression system, a second motor coupled the shaft
and configured to provide the supplemental power, and an interface
structure configured to be selectively affixed to the compression
system to attach the modular motor assembly to the compression
system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The advantages of the present techniques are better
understood by referring to the following detailed description and
the attached drawings, in which:
[0018] FIG. 1 illustrates various representative examples of field
declines a given gas reservoir or field may experience;
[0019] FIGS. 2A and 2B are different perspective views of an
exemplary embodiment of a conventional system 200 for compressing
hydrocarbon gas;
[0020] FIG. 3 illustrates an exemplary embodiment of a compression
system for compressing hydrocarbon gas;
[0021] FIG. 4 illustrates an exemplary embodiment of a modular
motor assembly;
[0022] FIGS. 5A and 5B illustrate exemplary embodiments for
coupling modular motor assembly to a compression system;
[0023] FIG. 6 illustrates an exemplary embodiment of a modular
compressor assembly;
[0024] FIG. 7 illustrates an exemplary embodiment of a modular
compression system;
[0025] FIG. 8 illustrates another exemplary embodiment of a modular
compression system; and
[0026] FIG. 9 is a flowchart of an exemplary embodiment of a method
for processing a gas stream.
DETAILED DESCRIPTION OF THE DRAWINGS
[0027] In the following detailed description section, specific
embodiments of the present techniques are described. However, to
the extent that the following description is specific to a
particular embodiment or a particular use of the present
techniques, this is intended to be for exemplary purposes only and
simply provides a description of the exemplary embodiments.
Accordingly, the techniques are not limited to the specific
embodiments described below, but rather, include all alternatives,
modifications, and equivalents falling within the spirit and scope
of the appended claims.
[0028] At the outset, for ease of reference, certain terms used in
this application and their meanings as used in this context are set
forth. To the extent a term used herein is not defined below, it
should be given the broadest definition persons in the pertinent
art have given that term as reflected in at least one printed
publication or issued patent. Further, the present techniques are
not limited by the usage of the terms shown below, as all
equivalents, synonyms, new developments, and terms or techniques
that serve the same or a similar purpose are considered to be
within the scope of the present claims.
[0029] As used herein, "compressor" may be defined a number of ways
and the particular definition intended for a given context set
forth herein may be selected from the following, as will be clear
to those of skill in the art. One definition indicates that
"compressor" refers to a device used to increase the pressure of an
incoming fluid by decreasing its volume. In another definition, a
"compressor" is a machine that increases the pressure of a gas by
the application of work (compression). Accordingly, a low pressure
gas (for example, 5 pounds per square inch gauge (psig)) may be
compressed into a high-pressure gas (for example, 1000 psig) for
transmission through a pipeline, or other processes. In yet another
definition, a "compressor" refers to a device for compressing a
working gas, including gas-vapor mixtures or exhaust gases, and
includes reciprocating compressors, piston compressors, rotary vane
or screw compressors, and devices and combinations capable of
compressing a working gas.
[0030] As used herein, "pump" may be defined a number of ways and
the particular definition intended for a given context set forth
herein may be selected from the following, as will be clear to
those of skill in the art. One definition indicates that "pump"
refers to a device that moves fluids (liquids or gases) by
mechanical action. Pumps operate by some mechanism, and consume
energy to perform mechanical work by moving the fluid.
[0031] As used herein, "turbine" may be defined a number of ways
and the particular definition intended for a given context set
forth herein may be selected from the following, as will be clear
to those of skill in the art. One definition indicates that
"turbine" refers to a rotary mechanical device that extracts energy
from a fluid flow and converts it into useful work.
[0032] FIG. 2A is an embodiment of a conventional system 200 for
compressing hydrocarbon gas. FIG. 2A is a cross-sectional side view
of the system 200. The system comprises an electric motor 15 and a
compressor 20 connected by one or more shafts 30. The electric
motor 15 is an adjustable speed alternating current (AC) or direct
current (DC) motor. In an embodiment, the compressor 20 and the
motor 15 are in hermetically sealed compartments within a casing 25
and separated by a partition 35. Although illustrated as a single
casing 25, in some embodiments casing 25 may comprise separate
casings, with one casing, for example, housing the motor 15 and one
casing housing the compressor 20, in which case the partition 35
represents two end walls, located adjacent one another, of the
respective pressure casings. In some embodiments, the casings can
be coupled via any known coupling technique. For example, the
casings may be coupled via flanges (not shown) that are fitted with
bolts. The compressor 20 has an associated inlet 40 for receiving
gas and outlet 45 for discharging gas. Gas flows into inlet 40 and
is discharged out of outlet 45. In an embodiment, the partition 35
allows for some of the gas that is processed to enter the cavity
surrounding the motor 15, in which case the motor is affected by
the compression process taking place in the volume around the
compressor 20. In some embodiments, cooling of the motor or motor
casing may be beneficial to dissipate the motor losses and the
fluid frictional losses. These facilities are not shown.
[0033] The motor 15 is used to drive the compressor 20 via one or
more shafts 30. As one of ordinary skill in the art would
understand, the system 200 also includes a plurality of bearings
(not shown), some of which are radial bearings and at least one of
which is a thrust bearing. These bearings may be magnetic bearings
in which case a power source and associated controls are used to
control the magnetic bearings. A shaft associated with the motor 15
and a shaft associated with the compressor 20 are illustrated as
one shaft 30 for simplicity, but the shafts of the motor 15 and
compressor 20 may be separate shafts that are connected via any
known type of coupling (not shown), such as a stiff coupling, a
flexible coupling, a fluid coupling, a magnetic coupling, an
elastomeric coupling, or a gear coupling. Alternatively, or
additionally, the shafts may be coupled using any known type of
clutch or gear. In an embodiment, the system 200 is hermetically
sealed such that there is no shaft penetrating the pressure casing
25.
[0034] The motor 15 and compressor 20 are surrounded by the
pressure casing 25 to keep the motor 15 and compressor 20
hermetically sealed. The pressure casing 25 is substantially
cylindrical and may be supported by a plurality of support members
55 resting upon or coupled to a support, such as base plate 50.
FIG. 2B is an end view of the system 200 that illustrates an
embodiment of support members 55 and casing 25.
[0035] The conventional system 200 does not provide much
flexibility to be able to match reservoir depletion pressure curves
as it is typically designed for narrow input pressure ranges.
Disclosed herein are compression systems that use modular
components so that the systems can be quickly, efficiently, and
cost-effectively reconfigured to adjust to decreasing inlet
pressure.
[0036] FIG. 3 illustrates an example embodiment of a compression
system 300 for compressing hydrocarbon gas. In some embodiments,
the system 300 shares some similarities to system 200, and
components that are similar to system 200 are labeled similarly and
not explained further. The compression system 300 comprises
pressure casing 325 that includes removable plates 65 and flanges
60. A cross-section of the system is shown in which an outline of
the flanges 60 at the top and bottom of the pressure casing 325 are
illustrated, but each flange 60 may wrap around a circumference of
the pressure casing 325. All the flanges discussed herein may share
this characteristic. The flange design and attachment method may be
variable.
[0037] In some embodiments, the casing 325 includes a compressor
compartment and a motor compartment. In an embodiment, the
compartment within casing 325 corresponding to motor 15 and the
compartment within casing 325 corresponding to compressor 20 are
hermetically sealed, and the compartments may be isolated or sealed
from each other by partition 35. The system 300 is a modular system
that allows for removal of one or two of the plates 65 to add
additional motors or compressors as needed, as explained more fully
below. Although the removable plates 65 are illustrated as
occupying an entire area of each end of the system 300, in an
embodiment, a removable plate 65 may occupy only a portion of an
end area to allow shaft penetration from another motor or
compressor as explained more fully below.
[0038] As discussed previously, in some embodiments the motor 15
and compressor 20 each have separate pressure casings, in which
case partition 35 represents adjacent end walls of two pressure
casings that are coupled in known manners. Modular casings provide
for replacing the current motor 15 or compressor 20 with one more
suitable to a new compression duty by, for example, replacing the
desired component along with its casing. In a configuration in
which the compression system 300 comprises two pressure casings,
one each for motor 15 and compressor 20, the two pressure casings
may be referred to as a single pressure casing 325 of the
compression system 300.
[0039] The casing 325 is strong and rigid enough that another motor
or compressor can be added to either or both ends of system 300
without using support members to support the added motor and/or
compressor. Also, the support members 55 and baseplate 50 in a
modular system are designed to support additional weight to be
added on either or both ends of system 300.
[0040] In an embodiment, the system 300 is a compressor-motor
arrangement referred to as a hermetically sealed compact compressor
(HSCC). HSCCs include motor-driven compressors in a single casing
without machinery penetrations of the pressure envelope so that
there are no rotary seals and the rotor system is supported via
magnetic bearings that are cooled by the process gas. In contrast,
in conventional compressors an oil system cools and lubricates one
or more bearings which are in the atmosphere and separated from the
process gas by the rotary seals.
[0041] FIG. 4 illustrates an example embodiment of a modular motor
assembly 400. The motor assembly 400 comprises an electric motor
405, a shaft 470, a pressure casing 410, and a partition 465
configured as illustrated in FIG. 4. The electric motor 405 is an
adjustable speed AC or DC motor. As one of ordinary skill in the
art would understand, the assembly 400 also includes at least one
bearing (not shown), which may include a radial bearing and/or
thrust bearing. In an embodiment, the at least one bearing includes
a magnetic bearing, and the motor assembly includes controls and a
power supply for the magnetic bearing that is external to the
pressure casing 410. In the exemplary embodiment shown, the motor
405 is a double-ended motor and can provide power off either end of
the shaft 470. The motor assembly 400 is configured to be coupled
to other modules to create a system for compressing hydrocarbon
gas. In some embodiments, the motor assembly 400 is used to
supplement the power provided in a preexisting modular compression
system.
[0042] FIGS. 5A and 5B illustrate example embodiments for coupling
modular motor assembly 400 to a compression system, such as
compression system 300. FIG. 5A illustrates a compression system
500 in which modular motor assembly 400 is coupled to a compressor
20 in a motor-compressor-motor configuration. The configuration in
FIG. 5A is an example of motors connected in a tandem
configuration. FIG. 5B illustrates a compression system 510 in
which modular motor assembly 400 is coupled to the compressor 20 in
a motor-motor-compressor configuration. The configuration in FIG.
5B is an example of motors connected in a series or drive-through
configuration.
[0043] In one embodiment, system 300 is originally configured or
staged to receive gas at the inlet 40 at a specified range of
pressures. For example, system 300 could be configured to receive
gas at an initial point along a reservoir depletion curve for the
reservoir that the system 300 is serving. Example reservoir
depletion curves are discussed previously with respect to FIG. 1.
As the pressure of the inlet gas decreases over time, the system
300 may reach a point where an extra motor, such as motor assembly
400, is beneficial to drive the compressor 20. Referring to FIG.
5A, the shaft 470 is aligned with shaft 30 such that there is a
common center of rotation.
[0044] The speed of the motor 405 is synchronized with the motor
15, and the power-split is controlled so that overload does not
occur. A coupling 475 is used to transfer power from the motor 405
and shaft 470 to shaft 30. The coupling 475 is any known apparatus
for mechanical power transmission. For example, the coupling 475
may be a stiff coupling, a flexible coupling, a fluid coupling, a
gear, or any other suitable type of coupling. Thus, the shaft 470
is drivably connected to the shaft 30.
[0045] When motor assembly 400 is first added, the demand for extra
power from the motor 405 starts small and increase over time as
inlet pressure decreases. At some point, the compressor 20 may also
need to be resized or replaced to accommodate lower gas pressures.
Flanges 60 and 460 are mated or coupled to attach motor assembly
400 to system 300. For example, flanges 60 and 460 may be
configured such that bolts are inserted to couple the assembly 400
to system 300. In an embodiment, partition 465 keeps motor assembly
400 hermetically sealed from system 300. The partition 465 may
include a plate having a hole for at least one radial bearing and
the shaft 470. The in another embodiment, the system 500 is
hermetically sealed, but partitions 35 and 465 either are not
present or the partitions are not fully sealed so that motor 15,
compressor 20, and/or motor 405 are not hermetically sealed from
each other.
[0046] FIG. 5B illustrates a compression system 510 in which
modular motor assembly 400 is coupled to a compressor 20 in a
motor-motor-compressor configuration as illustrated. The
configuration in FIG. 5B is an example of motors connected in a
series or drive-through configuration. As described with respect to
FIG. 5A, in one embodiment, system 300 is originally configured or
staged to receive gas at inlet at a specified range of pressures.
As the pressure of the inlet gas decreases over time, the system
300 may reach a point where an extra motor, such as motor assembly
400, is beneficial to drive the compressor 20. The shaft 470 is
aligned with shaft 30 such that there is a common center of
rotation. Various shapes incorporated into the flanges 60 and 460
can be used to ensure alignment of rotating elements, such as
shafts 30 and 470. For example, there may be one or more
protrusions (not shown) extending from flange 60 and one or more
corresponding indentions (not shown) in flange 460 that are
configured to be mated to ensure alignment of rotating elements. An
example of the mated protrusion(s) and indention(s) are male-female
connections.
[0047] A coupling 475 is used to transfer power from the motor 405
and shaft 470 to shaft 30. The coupling 475 is any known apparatus
for mechanical power transmission. Other details with respect to
system 510 are similar to system 500. One exception is that when
motors are connected in series, such as motors 15 and 405, the
shaft on the motor delivering power to the compressor, in this case
shaft 30, should be sized in accommodate a higher power delivery
than just power delivered by motor 15 in isolation.
[0048] There are no feet on motor assembly 400, which is part of
the benefit of using a modular approach. A new baseplate 50 does
not need to be used when modular components are added as the
baseplate 50 is pre-selected to accommodate any additional weight
that could be added later by adding modular components. That is,
the motor assembly 400 is cantilevered from the system 300 with its
weight only supported by the attachment to the system 300. In some
embodiments, the base plate is sized to accommodate support members
attached only to the system 300, and since the motor assembly 400
is suspended or cantilevered by the assembly 300, there is no need
for a larger or a second base plate.
[0049] Furthermore, the flanges 60 and 460 may be designed to
support this cantilevered configuration. For example, a thickness
of at least one of the flanges 60 and 460 may be engineered to
support the weight of motor assembly 400. Fasteners, such as bolts,
that couple the flanges 60 and 460 together may be similarly
engineered. One or more parts of the flanges 60 and 460 may be
characterized as an interface structure.
[0050] FIG. 6 illustrates an example embodiment of a modular
compressor assembly 600. The compressor assembly 600 comprises
compressor 620, shaft 670, pressure casing 610 with flange 660,
inlet 640, outlet 645, and partition 665 configured as illustrated
in FIG. 6. The compressor assembly 600 is configured to be coupled
to other modules to create a system for compressing hydrocarbon
gas. In some embodiments, the compressor assembly 600 is used to
supplement the compression capability of a preexisting compression
system.
[0051] FIG. 7 illustrates an example embodiment of a modular
compression system 700. The modular compression system 700 includes
a compressor assembly 600 coupled to the compression system 500. In
this embodiment, compressor assembly 600 is coupled to the system
500 described earlier, in which motor assembly 400 is added to
system 300. The system 700 is configured such that compressor 20
receives gas from a reservoir via inlet 40 and discharges gas via
outlet 45. Additional piping may be needed to connect outlet 45 to
inlet 640 of compressor assembly 600 to further compress the gas
flow. Gas is discharged via outlet 645. In some embodiments, a
cooler is included in the external piping connecting compressor 20
to compressor 620. The cooler may be used to cool the temperature
of the gas processed by compressor 20 before gas is channeled to
the compressor 620.
[0052] In one embodiment, once power needed from motor 405 exceeds
a threshold, compressor assembly 600 is added to the compression
system. A coupling 675 is used to transfer power from the motor 405
and shaft 470 to compressor shaft 670. The coupling 675 is any
known apparatus for transmitting mechanical power from one shaft to
another.
[0053] FIG. 8 illustrates another example embodiment of a modular
compression system 800. The modular compression system includes
system 700 described previously and further includes a heat
exchanger 750 and a separator 805. A stream of a hydrocarbon
mixture including gas is illustrated as 760a. The stream enters
heat exchanger 750 and is cooled before leaving heat exchanger and
entering separator 805.
[0054] The stream exiting the heat exchanger 750 may enter
separator 805 and may include a mixture of free liquid or liquid
aerosols and gas. The separator 805 separates these liquids from
the gas. In one embodiment, the stream exiting the heat exchanger
750 includes oil, water, and gas, and the separator 805 separates
these components. As illustrated, oil exits in stream 810, water
exits the separator 805 in stream 820, and gas exits the separator
805 in stream 760b. Alternatively, the separator 805 may function
as three-phase separator, for example separating sand, liquid
(e.g., more than one type of liquid), and gas. Regardless of the
type of separation, the stream 760b includes primarily gas. The
stream 760b enters a casing housing compressor 20 followed by
compression by another compressor 620, and the stream exits the
casing housing compressor 620 as stream 760c.
[0055] Thus, a modular compression system may include not only
compressors and motors, but rather all the components typically
needed for a full compression system, including heat exchangers and
separators. A heat exchanger and separator may be modular as well.
For example, as illustrated in FIG. 8, the heat exchanger 750
includes a flange 860. The flange 860 is mated or coupled to flange
60 to attach the separator 805 to the system 300. The heat
exchanger 750 may be integral with the separator 805, or the heat
exchanger 750 may be modular with a flange (not shown) for mating
the heat exchanger 750 to the separator 805.
[0056] The heat exchanger 750 and separator 805 do not include
separate support members, as the support members 55 below the
system 300 are designed to support additional weight to be added on
either or both ends of system 300 to allow for a flexible, modular
configuration.
[0057] As shown in FIG. 8, the streams 760a-760c flow between
sections or modules external to the sections. For example, piping
external to the sections shown in FIG. 8 is used to route gas
streams. However, the gas routing may also be performed using
internal passages between sections. Register fits may be
incorporated into flanges that couple one section to another to
ensure alignment of internal piping. Internal piping may be coupled
and sealed in a manner similar to coupling and sealing of shafts 30
and 470 described previously. In embodiments with internal piping,
an in-line cooler (in the piping) or a cooling jacket around the
casing circumference may be used, thus helping to cool the gas as
it is being compressed, as opposed to waiting for the final
discharge. Such embodiments can save external piping connections,
space, and weight.
[0058] In some circumstances, gas flow is too high to be processed
by a single compressor. In such circumstances, a gas stream need
not be processed all in series, e.g., from one compressor into
another such as shown in FIG. 8 (i.e., gas is processed first by
compressor 20 followed by compressor 620). For example, a gas
stream may be divided into two or more streams and processed in
parallel. In an embodiment, a gas stream is divided into two
streams, with a first stream including a first fraction of the
total gas stream and a second stream including a second fraction of
the total gas stream. The two streams may be processed in different
parts of a compressor or other part of a modular system.
[0059] In an embodiment, a gas stream is divided into two streams,
with a first stream processed by a first compressor, such as
compressor 20 in modular system 700, and a second stream processed
by a second compressor, such as compressor 620. In an embodiment,
the first stream flows into inlet 40 and is discharged out of
outlet 45, and the second stream flows into inlet 640 and is
discharged out of outlet 645. In this manner, the first and second
streams can be processed in parallel.
[0060] FIG. 9 is a flowchart setting forth an exemplary embodiment
of a method 900 for processing a gas stream. The method 900 may be
implemented using a modular compression system, such as any of the
modular compression systems described herein. The method begins in
block 910. In block 910, a gas stream is compressed using a modular
compressor system, such as system 300. For example, a gas stream
derived from a reservoir is received at an inlet, compressed by a
compressor, and discharged at an outlet of the compressor. The
compressor is powered by a motor, such as motor 15.
[0061] Next in decision block 920, a determination is made whether
the pressure of the input gas stream has fallen below a threshold
pressure. The pressure may decrease over time due to the
characteristics of the gas reservoir being depleted. For example,
as discussed previously with respect to FIG. 1, gas reservoir
pressure typically declines in a gradual manner. The compression
system may include a pressure sensor located at or near an inlet
for measuring the pressure. The sensor may send electrical signals
to a controller or other measurement system.
[0062] If it is determined that pressure exceeds a threshold, the
method returns to block 910 and gas continues to be processed using
the original modular compressor system. However, if it is
determined that pressure is less than the threshold, the method 900
proceeds to block 930. In block 930, one or more additional
sections or components are added to the modular compressor system.
For example, as shown in FIGS. 5A and 5B, an additional motor
assembly, such as motor assembly 400 may be added. As another
example, an additional compressor assembly, such as compressor
assembly 600, may be added instead of or in addition to another
motor assembly. Additional motors and/or compressors may be added
in any order. For example, motors may be connected in a series
(e.g., see FIG. 5B) or in a tandem configuration (e.g., see FIG.
5A). The same may be done with compressors.
[0063] During block 930, gas processing may be temporarily halted
or suspended while the modular compressor system is being
reconfigured. Further, during block 930, a portion of a pressure
casing may be removed to allow a modular motor assembly, such as
motor assembly 400, to couple to the compressor, such as compressor
20. For example, pressure casing 325 is one example of a pressure
casing, and removable plate 65 may be removed during block 930 in
order to connect the motor assembly 400 to the compressor 20.
[0064] After additional sections are added in block 930 to create a
rerated modular compressor system, the process proceeds to block
940. In block 940, the gas stream is compressed using the rerated
modular compressor system.
[0065] Blocks 920-940 may be repeated as needed during the life of
a reservoir. For example, additional sections or components may be
added as needed each time inlet pressure falls below a threshold.
Thus, there may be a series of progressively decreasing pressure
thresholds below which an additional section is added. In this
manner, a modular compression system can efficiently track a
reservoir depletion pressure or flow rate curve to provide
satisfactory compression performance at different points on the
pressure curve.
[0066] Although exemplary embodiments discussed herein in with
respect to FIGS. 2-9 are directed to compression systems, a person
of ordinary skill in the art would understand that the principles
apply to many systems that include a driver and a driven element,
such as a pump. Furthermore, turbines are sometimes used in
compression systems, in addition to or in lieu of electric motors,
to recover energy from fluid streams. Thus, turbines can be one of
the modular components in a modular compression system as disclosed
herein. For example, the compressor 20 in FIG. 3 may be driven by
either a motor, a turbine, or both. As another example, the
compressor 20 or compressor 620 in the system 700 in FIG. 7 may
also be driven by either a motor, a turbine, or both. The terms
"driver" and "driving element" may be used synonymously. Examples
of a "driving element" include an electric motor and a turbine.
[0067] Embodiments of the invention may include any combinations of
the methods and systems shown in the following numbered paragraphs.
This is not to be considered a complete listing of all possible
embodiments, as any number of variations can be envisioned from the
description above.
[0068] 1. A modular compression system for matching an operation
range to a reservoir depletion condition, the modular compression
system comprising:
[0069] a compressor arranged to compress a hydrocarbon gas from a
well in the reservoir;
[0070] a driving element coupled to the compressor and configured
to provide power to the compressor;
[0071] a pressure casing surrounding the compressor and the driving
element; and
[0072] a modular electric motor assembly configured to be
selectively attachable and coupled to the compressor and the
pressure casing, the modular electric motor being arranged to
provide supplemental power to the compressor to change the capacity
of the modular compression system to compress the hydrocarbon
gas.
[0073] 2. The modular compression system of paragraph 1, further
comprising:
[0074] a base plate; and
[0075] at least one support member connected between the pressure
casing and the base plate configured to support the compressor, the
driving element, and the modular electric motor.
[0076] 3. The modular compression system of paragraph 2, further
comprising:
[0077] a first flange on the pressure casing;
[0078] a second flange on the modular electric motor, wherein the
first flange is connected to the second flange, and wherein the
modular electric motor assembly is not in contact with any support
members connected to the base plate.
[0079] 4. The modular compression system of any of paragraphs 1-3,
wherein the modular electric motor assembly is coupled to the
driving element in a series driving configuration or in a tandem
configuration.
[0080] 5. The modular compression system of any of paragraphs 1-3,
further comprising a cooling water jacket on the periphery of the
pressure casing.
[0081] 6. The modular compression system of any of paragraphs 1-5,
further comprising: a modular separator having a first inlet
configured to receive a fluid mixture and an outlet configured to
produce a gas, and wherein the outlet is coupled to the compressor
at a second inlet of the compressor.
[0082] 7. The modular compression system of paragraph 6, further
comprising:
[0083] a modular heat exchanger coupled to an end of the modular
separator, the modular separator coupled to an end of the
compressor.
[0084] 8. The modular compression system of any of paragraphs 1-7,
further comprising a modular compression assembly drivably
connected to both the driving element and the modular electric
motor assembly.
[0085] 9. The modular compression system of paragraph 8, wherein
the modular compression system is configured to divide the input
gas stream into a first gas stream and a second gas stream, and
wherein the modular compression system is configured to compress
the first gas stream and the second gas stream in parallel.
[0086] 10. The modular compression system of any of paragraphs 1-9,
wherein the driving element is an electric motor.
[0087] 11. The modular compression system of any of paragraphs 1-9,
wherein the driving element is a turbine.
[0088] 12. A method for processing a gas stream using a modular
compression system, wherein the modular compression system
comprises a driving element mechanically coupled to a compressor by
at least one shaft, and wherein the modular compression system
further comprises a pressure casing surrounding the driving element
and the compressor, the method comprising:
[0089] removing a portion of the pressure casing to allow a modular
electric motor assembly to couple to the compression system;
and
[0090] connecting the modular electric motor to the compression
system to boost drive power supplied to the compressor.
[0091] 13. The method of paragraph 12, further comprising:
[0092] measuring an inlet gas pressure; and
[0093] determining that the inlet gas pressure is less than a
threshold,
[0094] wherein the removing and the connecting are performed in
response to the determining that the inlet gas pressure is less
than a threshold.
[0095] 14. The method of paragraph 13, wherein the method further
comprises:
[0096] determining that the inlet gas pressure is less than a
second threshold; [0097] in response to the determining that the
inlet gas pressure is less than the second threshold, connecting a
modular compressor assembly to the modular electric motor to
provide additional compression to the gas stream.
[0098] 15. The method of any of paragraphs 12-14, wherein the
modular electric motor connects to the compressor to drive the
compressor in a tandem motor configuration or a drive-through
configuration.
[0099] 16. The method of any of paragraphs 12-14, wherein the
method further comprises:
[0100] determining that the inlet gas pressure is less than a
second threshold; [0101] in response to the determining that the
inlet gas pressure is less than the second threshold: [0102]
opening the pressure casing; [0103] removing a component, wherein
the component comprises either the compressor or the driving
element; [0104] replacing the component with a second component of
increased capacity to provide greater compression to the gas
stream; and [0105] closing the pressure casing.
[0106] 17. The method of any of paragraphs 12-16, wherein the
driving element is one of an electric motor and a turbine.
[0107] 18. A modular apparatus comprising:
[0108] a modular electric motor assembly configured to selectively
attach to and provide supplemental power to a compression system,
wherein the compression system comprises a first motor, the modular
electric motor assembly comprising: [0109] a shaft configured to
couple to the compression system; [0110] a second motor coupled the
shaft and configured to provide the supplemental power; and [0111]
an interface structure configured to be selectively affixed to the
compression
[0112] system to attach the modular electric motor assembly to the
compression system.
[0113] 19. The modular apparatus of paragraph 18, wherein the
modular electric motor assembly further comprises a partition, and
wherein the shaft extends beyond the partition and is mechanically
coupled to the compression system.
[0114] 20. The modular apparatus of paragraphs 18 or 19, further
comprising a compression system, wherein the compression system
further comprises a first compressor and a second shaft, and
wherein the shaft is mechanically coupled to the second shaft to
assist with driving the first compressor.
[0115] 21. The modular apparatus of paragraph 20, further
comprising a modular compressor assembly selectively and
mechanically coupled to the compression system, wherein the modular
compressor assembly comprises a second compressor.
[0116] 22. The modular apparatus of paragraph 21, wherein the first
motor and the second motor are configured to transfer mechanical
power to the first compressor and the second compressor.
[0117] 23. The modular apparatus of paragraph 19, wherein the
modular electric motor assembly further comprises:
[0118] a pressure casing; and
[0119] a flange surrounding a circumference of the pressure casing,
[0120] wherein the flange is configured to couple to the interface
structure of the modular electric motor assembly, the flange being
configured to support the weight of the modular electric motor
assembly.
[0121] While the present techniques may be susceptible to various
modifications and alternative forms, the embodiments discussed
above have been shown only by way of example. However, it should
again be understood that the techniques is not intended to be
limited to the particular embodiments disclosed herein. Indeed, the
present techniques include all alternatives, modifications, and
equivalents falling within the true spirit and scope of the
appended claims.
* * * * *