U.S. patent application number 14/123215 was filed with the patent office on 2014-06-26 for system for gathering gas from a gas field comprising a high efficient high pressure compressor.
The applicant listed for this patent is Arthur Kauffeld, Bob Okhuijsen, Bernd Wacker. Invention is credited to Arthur Kauffeld, Bob Okhuijsen, Bernd Wacker.
Application Number | 20140178208 14/123215 |
Document ID | / |
Family ID | 46208456 |
Filed Date | 2014-06-26 |
United States Patent
Application |
20140178208 |
Kind Code |
A1 |
Okhuijsen; Bob ; et
al. |
June 26, 2014 |
SYSTEM FOR GATHERING GAS FROM A GAS FIELD COMPRISING A HIGH
EFFICIENT HIGH PRESSURE COMPRESSOR
Abstract
A system includes a high pressure compressor having a gas input
and a gas output. The gas input is coupleable to a gas field for
receiving a gathered gas with a first gas pressure, and the gas
output is coupleable to a gas export system for providing the gas
with a second gas pressure, which is higher than the first gas
pressure, to the gas export system. The system also includes a
measuring unit coupled to the gas input. The measuring unit
measures an input mass flow value indicative of an input mass flow
at the gas input. The system also includes a mass flow control unit
that is coupled to the measuring unit for receiving the measured
input mass flow value and the gas input for controlling the input
mass flow such that the measured input mass flow value corresponds
to a set point input mass flow value.
Inventors: |
Okhuijsen; Bob; (Assen,
NL) ; Kauffeld; Arthur; (Assen, NL) ; Wacker;
Bernd; (Herzogenaurach, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Okhuijsen; Bob
Kauffeld; Arthur
Wacker; Bernd |
Assen
Assen
Herzogenaurach |
|
NL
NL
DE |
|
|
Family ID: |
46208456 |
Appl. No.: |
14/123215 |
Filed: |
May 21, 2012 |
PCT Filed: |
May 21, 2012 |
PCT NO: |
PCT/EP2012/059386 |
371 Date: |
March 7, 2014 |
Current U.S.
Class: |
417/2 ;
417/26 |
Current CPC
Class: |
F04D 15/0011 20130101;
F04D 25/16 20130101; F04D 27/0207 20130101; F04D 27/0215 20130101;
F04D 15/0005 20130101 |
Class at
Publication: |
417/2 ;
417/26 |
International
Class: |
F04D 27/02 20060101
F04D027/02; F04D 15/00 20060101 F04D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2011 |
EP |
11168122.7 |
Claims
1. A system for gathering a gas from a gas field, the system
comprising: a high pressure compressor comprising a gas input and a
gas output, wherein the gas input is coupleable to the gas field
for receiving the gas gathered from the gas field with a first gas
pressure, wherein the gas output is coupleable to a gas export
system for providing the gas with a second gas pressure to the gas
export system, and wherein the second gas pressure is higher than
the first gas pressure; a measuring unit coupled to the gas input,
wherein the measuring unit is configured to measure an input mass
flow value that is indicative of an input mass flow at the gas
input; a first low pressure compressor that is connectable to a
first wellhead arrangement of the gas field for receiving the gas
from the first wellhead arrangement, wherein the first low pressure
compressor is connected to the gas input for providing the gas to
the gas input with a first mass flow; a second low pressure
compressor that is connectable to a second wellhead arrangement of
the gas field for receiving the gas from the second wellhead
arrangement, wherein the second low pressure compressor is
connected to the gas input for providing the gas to the gas input
with a second mass flow; and a mass flow control unit, wherein the
mass flow control unit is coupled to the measuring unit for
receiving the measured input mass flow value, wherein the mass flow
control unit is further connected to the first low pressure
compressor for controlling the first low pressure compressor, and
the second low pressure compressor for controlling the second low
pressure compressor such that the first mass flow and the second
mass flow are controllable for controlling the input mass flow at
the gas input such that the measured input mass flow value
corresponds to a set point input mass flow value.
2. The system according to claim 1, further comprising: a first
delivery valve that is connectable to the first wellhead
arrangement of the gas field for receiving the gas from the first
wellhead arrangement, wherein the first delivery valve is connected
to the gas input for providing the gas to the gas input with a
further first mass flow; and a second delivery valve that is
connectable to the second wellhead arrangement of the gas field for
receiving the gas from the second wellhead arrangement, wherein the
second delivery valve is connected to the gas input for providing
the gas to the gas input with a further second mass flow, wherein
the mass flow control unit is connected to the first delivery valve
for controlling the first delivery valve and the second delivery
valve for controlling the further second mass flow such that the
further first mass flow and the further second mass flow are
controllable for controlling the input mass flow at the gas
input.
3. The system according to claim 1, further comprising: a return
flow tubing that is connected to the gas output for bleeding off a
part of the gas from the gas output and is connected to the gas
input for injecting the part of the gas in the gas input, wherein
the mass flow control unit is coupled to the return flow tubing for
controlling the bleeding off of the part of the gas from the gas
output and for controlling the injecting of the part of the gas in
the gas input such that the input mass flow at the gas input is
controllable.
4. The system according to claim 1, further comprising: a bypass
tubing that is connected to the gas input for bleeding off a
further part of the gas from the gas input, wherein the mass flow
control unit is coupled to the bypass tubing for controlling the
bleeding off of the further part of the gas from the gas input such
that the input mass flow at the gas input is controllable.
5. A method for controlling a gas mass flow of a system for
gathering gas from a gas field, the method comprising: measuring an
input mass flow at a gas input of a high pressure compressor,
wherein the gas input receives the gas gathered from the gas field
with a first gas pressure, wherein the high pressure compressor
comprises a gas output for providing gas with a second gas pressure
to a gas export system, and wherein the second gas pressure is
higher than the first gas pressure; measuring, by a measuring unit
that is coupled to the gas input, an input mass flow value that is
indicative of an input mass flow at the gas input; receiving, by a
mass flow control unit, the measured input mass flow value, wherein
a first low pressure compressor is connectable to a first wellhead
arrangement of the gas field for receiving the gas from the first
wellhead arrangement, wherein the first low pressure compressor is
connected to the gas input for providing the gas to the gas input
with a first mass flow, wherein a second low pressure compressor is
connectable to a second wellhead arrangement of the gas field for
receiving the gas from the second wellhead arrangement, and wherein
the second low pressure compressor is connected to the gas input
for providing the gas to the gas input with a second mass flow; and
controlling, by the mass flow control unit coupled to the gas
input, the input mass flow, wherein the mass flow control unit is
coupled to the measuring unit for receiving the measured input mass
flow value, and wherein the mass flow control unit is further
connected to the first low pressure compressor for controlling the
first low pressure compressor and the second low pressure
compressor for controlling the second low pressure compressor such
that the first mass flow and the second mass flow are controllable
for controlling the input mass flow at the gas input such that the
measured input mass flow value corresponds to a set point input
mass flow value.
6. The system according to claim 1, further comprising: a return
flow tubing that is connected to the gas output for bleeding off a
part of the gas from the gas output and is connected to the gas
input for injecting the part of the gas in the gas input, wherein
the mass flow control unit is coupled to the return flow tubing for
controlling the bleeding off of the part of the gas from the gas
output and for controlling the injecting of the part of the gas in
the gas input such that the input mass flow at the gas input is
controllable.
7. The system according to claim 2, further comprising: a bypass
tubing that is connected to the gas input for bleeding off a
further part of the gas from the gas input, wherein the mass flow
control unit is coupled to the bypass tubing for controlling the
bleeding off of the further part of the gas from the gas input such
that the input mass flow at the gas input is controllable.
8. The system according to claim 3, further comprising: a bypass
tubing that is connected to the gas input for bleeding off a
further part of the gas from the gas input, wherein the mass flow
control unit is coupled to the bypass tubing for controlling the
bleeding off of the further part of the gas from the gas input such
that the input mass flow at the gas input is controllable.
Description
[0001] The present application is a .sctn.371 nationalization of
PCT Application No. PCT/EP2012/059386, filed May 21, 2012, and
designating the United States, which, in turn, claims the benefit
of EP 11168122.7, filed on May 30, 2011, the entire disclosures of
which are incorporated by reference herein.
FIELD
[0002] The present embodiments relate to a system for gathering gas
from a gas field and to a method for controlling a gas mass flow of
a system for gathering gas from a gas field.
BACKGROUND
[0003] In the technical field of gas gathering, gas is gathered
from conventional gas field types, and unconventional gas field
types exist.
[0004] In conventional gas fields, the stored gas includes an
initially high pressure such that further compression by external
compressors is not needed in the beginning. After years of
free-flow production, a high pressure central compressor (e.g., of
a centrifugal type compressor) is installed for another couple of
years. In the end of the gas field lifetime, low pressure wellhead
compressors are implemented and connected to the respective
wellheads of the gas field. The high pressure central compressor
and the low pressure wellhead compressor are adapted for sucking
the gas out of the gas field and generating a high pressure gas
flow for subsequent gas export systems, such as pipelines or gas
generators.
[0005] In unconventional gas fields, such as tight gas, shell gas
or coal bed methane gas fields, the gas pressure inside the gas
field decreases in a short time interval, such that central high
pressure compressors and low pressure wellhead compressors are used
from the beginning of the gathering of the gas from the gas
field.
[0006] Up to now, the low pressure wellhead compressors and the
high pressure central compressor are configured as separate and
independent subsystems. The low pressure wellhead compressors and
the high pressure wellhead compressor may form independent and
separated units. The high pressure central compressor is optimized
for a small range of inlet pressures and inlet mass flow values.
The low pressure wellhead compressors are optimized for individual
ranges of respective inlet pressures and mass flows. Each low
pressure wellhead compressor thus produces an output pressure and
an output mass flow of gas without considering the small range of
inlet pressures and mass flow of gas at which the high pressure
central compressor works efficiently. A variation of the gas
pressure in the gas field does not affect the efficiency of the low
pressure wellhead compressors dramatically, whereas the efficiency
of the subsequent high pressure central compressor is affected
dramatically during pressure changes. The gathering of the gas is
thus inefficient if the high pressure central compressor is not
working under an efficient working point for which the high
pressure central compressor is configured for (e.g., the inlet gas
pressures and inlet mass flow of the high pressure central
compressor vary).
SUMMARY
[0007] The scope of the present invention is defined solely by the
appended claims and is not affected to any degree by the statements
within this summary.
[0008] The present embodiments may obviate one or more of the
drawbacks or limitations in the related art. For example, an
efficient gas gathering system for gathering gas from a gas field
is provided.
[0009] A system for gathering a gas from a gas field and a method
for controlling a gas mass flow of a system for gathering gas from
a gas field are provided.
[0010] In one embodiment, a system for gathering a gas from a gas
field is provided. The system includes a high pressure compressor
having a gas input and a gas output. The gas input is coupleable to
the gas field for receiving the gas gathered from the gas field
with a first gas pressure. The gas output is coupleable to a gas
export system for providing the gas with a second pressure to the
second gas export system. The second gas pressure is higher than
the first gas pressure. The system also includes a measuring unit
that is coupled to the gas input. The measuring unit measures an
input mass flow value that is indicative of an input mass flow at
the gas input. The system also includes a mass flow control unit.
The mass flow control unit is coupled to the measuring unit for
receiving the measured input mass flow value. The mass flow control
unit is coupled to the gas input for controlling the input mass
flow such that the measured input mass flow value corresponds to a
set point input mass flow value.
[0011] According to another embodiment, a method for controlling a
gas mass flow of a system for gathering gas from a gas field is
provided. According to the method, an input mass flow at a gas
input of a high pressure compressor is measured. The gas input
receives the gas gathered from the gas field with a first gas
pressure. The high pressure compressor includes a gas output for
providing gas with a second pressure to a gas export system. The
second gas pressure is higher than the first gas pressure. An input
mass flow value that is indicative of an input mass flow at the gas
input is measured by a measuring unit that is coupled to the gas
input. The measured input mass flow value is received by a mass
flow control unit. The input mass flow is controlled by the mass
flow control unit, which is coupled to the gas input. The mass flow
control unit controls the input mass flow such that the input mass
flow value at the gas input corresponds to a set point input mass
flow value.
[0012] By the above-described system and by the above-described
method for controlling a gas mass flow, gas (e.g., natural gas) may
be gathered from a conventional gas field or from an unconventional
gas field, in which tight gas, shell gas or coal bed methane gas is
gathered.
[0013] The high pressure compressor is installed between the gas
field and the gas export system. The high pressure compressor is
adapted for receiving the gas from the gas field with a first
pressure (e.g., approximately 10 to 14 bars) and adapted to
compress the gas up to a second gas pressure of approximately 60 to
90 bars used by the gas export system.
[0014] The high pressure central compressor may, for example, be of
a centrifugal type compressor and is most suitable for the gas
gathering in order to generate the high gas pressure for the
subsequent gas export system. The high pressure compressor includes
a small efficient range regarding the inputted mass flow and input
pressure in which the high pressure compressor works efficient. Due
to changes in inlet conditions, such as in the mass flow and in the
inlet gas pressure, a high impact on the operation efficiency is
caused.
[0015] The gas export system includes, for example, a pipeline
system for transporting the gas to a desired destination. The
export gas system may also include a gas power plant for generating
electricity or further gas treatment systems.
[0016] The measuring unit is coupled to the gas input of the high
pressure compressor and is adapted for measuring a variety of
parameters that are indicative of the input mass flow of the gas at
the gas input of the high pressure compressor. For example, the
measuring unit measures the input mass flow value (e.g., kg/s).
Additionally, the measuring unit may measure the first gas pressure
of the gas at the gas input and the second gas pressure at the gas
output. The measuring unit is also adapted for measuring the output
mass flow at the gas output of the high pressure compressor.
Additionally, the measuring unit may measure the composition of the
gas as well as the temperature of the gas at the gas input and the
gas output of the high pressure compressor.
[0017] The measured values (e.g., the measured input mass flow
value) are provided to the mass flow control unit. The mass flow
control unit compares the measured values (e.g., the input mass
flow value) with a given set point input mass flow value. If there
is a difference between the input mass flow value and the set point
input mass flow value, the mass flow control unit controls the
input mass flow value such that the input mass flow value
corresponds to the set point input mass flow value.
[0018] The set point input mass flow value defines the mass flow at
the gas input of the high pressure compressor, by which the high
pressure compressor is working at a working point of the high
pressure compressor and thus is working with the highest
efficiency. The working point is dependent on the pressure relation
between the first gas pressure at the gas input and the second gas
pressure at the gas output, the mass flow of the gas through the
high pressure compressor (e.g., the mass flow at the gas input) and
the rotational speed of the high pressure compressor.
[0019] Under given first pressures and second pressures, a set
point input mass flow value is thus given for running the high
pressure compressor at a working point of the high pressure
compressor and hence at a best efficiency. A deviation of the input
mass flow value causes a severe effect on the efficiency of the
high pressure compressor. For example, if the measured input mass
flow value differs dramatically to the set point input mass flow
value (e.g., at given first and second gas pressures), compressor
surge may occur.
[0020] The mass flow control unit is adapted for reducing the
deviation of the measured input mass flow value from the given set
point input mass flow value. The mass flow control unit may control
various subsystems for influencing the input mass flow of the gas
at the gas input. For example, the mass flow control unit may
control upstream installed low pressure compressors, delivery
valves or a mass flow in a return flow tubing and/or a mass flow of
a bypass tubing, which will be explained in more detail below.
[0021] By one or more of the present embodiments, even when the
gathered mass flow of gas from a gas field varies dramatically, a
predetermined and desired input mass flow at the gas input of the
high pressure compressor is adjustable by the mass flow control
unit such that the high pressure compressor is working
approximately at a working point of the high pressure compressor.
Hence, the efficiency of the high pressure compressor and hence the
gathering of gas from a gas field is more efficient.
[0022] According to a further exemplary embodiment, the system
includes a first low pressure compressor that is connectable to a
first wellhead arrangement of the gas field for receiving the gas
from the first wellhead arrangement. The first low pressure
compressor is connected to the gas input for providing the gas to
the gas input with a first mass flow. The system also includes a
second low pressure compressor that is connectable to a second
wellhead arrangement of the gas field for receiving the gas from
the second wellhead arrangement. The second low pressure compressor
is connected to the gas input for providing the gas to the gas
input with the second mass flow.
[0023] The mass flow control unit is connected to: a) the first low
pressure compressor for controlling the first low pressure
compressor; and b) the second low pressure compressor for
controlling the second low pressure compressor such that the first
mass flow and the second mass flow are controllable for controlling
the input mass flow at the gas input.
[0024] Each wellhead arrangement is connected to a borehole through
which gas of the gas field is gathered. A gas field may include a
plurality of boreholes. A respective wellhead arrangement is
attached to each borehole for gathering gas. Each wellhead
arrangement is connected to a respective low pressure compressor.
For example, if a wellhead arrangement delivers gas with
approximately 1 to 4 bars to the low pressure compressor, the low
pressure compressor increases the pressure up to approximately 5 to
20 bars. By increasing the pressure, a sucking effect is achieved,
such that the gas is sucked out of the respective borehole, so that
the respective mass flow through the low pressure compressor is
also increased.
[0025] For the low pressure wellhead compressors, screw-type or
reciprocating compressors may be used. These kinds of compressors
are relatively insensitive to changes in inlet conditions. The
compressors have a large operating range and may easily handle a
wide range of inlet pressure variations and inlet mass flows
variations under which an effective operation may still be
provided.
[0026] For example, the measuring unit is adapted for measuring
each mass flow and pressure at a respective gas input of a
respective low pressure compressor and at a gas output of a
respective low pressure compressor. This measured data is sent to
the mass flow control unit. The mass flow control unit also
receives the information of the input mass flow at the gas input of
the high pressure compressor. If more or less mass flow is needed
at the gas input of the high pressure compressor, the mass flow
control unit controls the respective low pressure compressors
(e.g., the first low pressure compressor and the second low
pressure compressor).
[0027] For example, the mass flow control unit receives the
information of the working points of the respective low pressure
compressors. For adjusting the desired input mass flow of the high
pressure compressor, each low pressure compressor is thus
controlled under consideration of respective working points such
that each low pressure compressors is operated more efficiently.
The overall efficiency of the system is thus increased.
[0028] Additionally or alternatively, according to a further
exemplary embodiment, the system includes a first delivery valve
that is connectable to a first wellhead arrangement of the gas
field for receiving the gas from the first wellhead arrangement.
The first delivery valve is connected to the gas input for
providing the gas to the gas input with a further first mass flow.
The system further includes a second delivery valve that is
connectable to a second wellhead arrangement of the gas field for
receiving the gas from the second wellhead arrangement. The second
delivery valve is connected to the gas input for providing the gas
to the gas input with a further second mass flow.
[0029] The mass flow control unit is connected to: a) the first
delivery valve for controlling the first delivery valve; and b) the
second delivery valve for controlling the second delivery valve,
such that the further first mass flow and the further second mass
flow are controllable for controlling the input mass flow at the
gas input.
[0030] The first and second delivery valves may be installed
between the respective first and second wellhead arrangement and
the respective first and second low pressure compressors.
Alternatively, the first and second delivery valves may be
installed behind (e.g., downstream) of the respectively first and
second low pressure compressors.
[0031] By controlling the respective delivery valves, the further
first mass flow and the further second mass flow of the gas
gathered from a respective borehole is adjustable and controllable
individually, such that a desired input mass flow of the gas at the
gas input of the high pressure compressor is adjustable.
[0032] In gas gathering systems (e.g., in conventional gas
gathering systems), gas may be gathered without using low pressure
compressors. In this case, only the delivery valves are installed
downstream of the wellhead arrangement in order to control mass
flow from the respective wellhead arrangement to the gas input of
the high pressure compressor.
[0033] According to a further exemplary embodiment, the system
includes a return flow tubing that is connected to the gas output
for bleeding off a part of the gas from the gas output and is
connected to the gas input for injecting the part of the gas in the
gas input. The mass flow control unit is coupled to the return flow
tubing for controlling the bleeding off of the part of the gas from
the gas output and for controlling the injecting of the part of the
gas in the gas input such that the input mass flow at the gas input
is controllable.
[0034] For example, if the measured input mass flow value is below
the set point input mass flow value, a part of the gas may be bled
off from the gas output and injected at the gas input, so that the
input mass flow is increased at the gas input. In the return flow
tubing, a control valve that is controllable by the mass flow
control unit may be installed.
[0035] By using the return flow tubing, an anti-surge system is
established. The mass flow control unit may act as a supervisory
system and controls the anti-surge system. By controlling the input
gas parameters (e.g., the input mass flow of the gas) and by
influencing the upstream located systems, such as the low pressure
compressors (e.g., wellhead compressors), the anti-surge system for
the high pressure compressor is safer and more efficient.
[0036] According to a further exemplary embodiment, the system
further includes a bypass tubing that is connected to the gas input
for bleeding off a further part of the gas from the gas input. The
mass flow control unit is coupled to the bypass tubing for
controlling the bleeding off of the further part of the gas from
the gas input such that the input mass flow at the gas input is
controllable.
[0037] For example, if the input mass flow is higher than the set
point input mass flow value, the bypass tubing may bleed off the
gas from the gas input (e.g., to the environment or to a further
use), for example, into a gas generator. By bleeding off the gas
from the gas input, the input mass flow is thus reduced until the
desired set point input mass flow value is adjusted.
[0038] By one or more of the present embodiments, the high pressure
compressor of a gas gathering system is controlled and operated
more efficiently. For example, predetermined set point input values
(e.g., set point input mass flow values) of the gas at the gas
input of the high pressure compressor are determined, so that
already at the design phase, the high pressure compressor may be
optimized for predetermined operating ranges in order to run more
efficiently at the given set point input mass flow values. For
example, the high pressure compressor may be configured with a
certain number of stator rings, cooling systems, etc., so that
already at the design phase of the high pressure compressor, an
optimized high pressure compressor is constructable.
[0039] By one or more of the present embodiments, optimized inlet
conditions for the high pressure compressor are generated, for
example, by adapting and controlling the low pressure compressors.
By controlling the low pressure compressors dependent on the
desired input values of the high pressure compressor, an
interconnected efficient and effective gathering system is
achieved.
[0040] Embodiments have been described with reference to different
subject matters. For example, some embodiments have been described
with reference to an apparatus, whereas other embodiments have been
described with reference to a method. However, a person skilled in
the art will gather from the above and the following description
that, unless otherwise noted, in addition to any combination of
features belonging to one type of subject matter, any combination
of features relating to different subject matters (e.g., between
features of the apparatus and features of the method) is considered
as to be disclosed with this application.
BRIEF DESCRIPTION OF THE DRAWING
[0041] FIG. 1 shows a gas gathering system according to an
exemplary embodiment.
DETAILED DESCRIPTION
[0042] In FIG. 1, similar or identical elements are provided with
the same reference signs.
[0043] FIG. 1 shows a system for gathering a gas from a gas field
170. The system includes a high pressure compressor 100 that
includes a gas input 101 and a gas output 102.
[0044] The gas input 101 is coupleable to the gas field 170 for
receiving the gas gathered from the gas field 170 with a first gas
pressure p1. The gas output 102 is coupleable to a gas export
system 130 for providing the gas with a second gas pressure p2 to
the gas export system 130. The second gas pressure p2 is higher
than the first gas pressure p1.
[0045] A measuring unit 110 is coupled to the gas input 101. The
measuring unit 110 measures (e.g., by sensor elements 111) an input
mass flow value (e.g., in kg/s) that is indicative of an input mass
flow {dot over (m)}.sub.1 at the gas input 101.
[0046] The system also includes a mass flow control unit 120. The
mass flow control unit 120 is coupled to the measuring unit 110 for
receiving the measured input mass flow value and the gas input 101
for controlling the input mass flow {dot over (m)}.sub.1 such that
the measured input mass flow value corresponds to a set point input
mass flow value.
[0047] The measuring unit 110 may also measure further mass flow
affecting parameters (e.g., the first pressure p1 and the
temperature at the gas input 101 and/or the second pressure p2, the
output mass flow {dot over (m)}.sub.2 and/or the temperature at the
gas output 102).
[0048] All measured data is provided to the mass flow control unit
120. The mass flow control unit 120 may calculate based on the
inputted data values, such as the input mass flow {dot over
(m)}.sub.1, the first pressure p1, the second pressure p2, the
output mass flow {dot over (m)}.sub.2, the respective gas
temperature at the gas input 101 and the gas output 102, a set
point input mass flow value (e.g., kg/s) at which the high pressure
compressor 100 is operated approximately at a working point. The
mass flow control unit 120 may be connected to the high pressure
compressor 100 for controlling, for example, the speed of rotation
of the high pressure compressor 100.
[0049] In FIG. 1, the tubing that transports the gas between the
system devices are shown by the solid lines, whereas the data lines
for transmitting measuring data and control data are shown with the
dotted lines.
[0050] Besides the high pressure compressor 100, in FIG. 1, further
components of the system for gathering gas are shown. From the gas
field 170, gas may be gathered through a plurality of boreholes. At
each borehole, a respective wellhead arrangement 151-154 is
attached. Downstream of each wellhead arrangement 151-154, a
respective delivery valve 161-164 is coupled. By controlling the
delivery valves 161-164, a respective mass flow from a respective
wellhead arrangement 151-154 to the gas input 101 may thus be
controllable.
[0051] In order to increase the amount of gathered gas from the gas
field, in all or in some tubes between the gas input 101 and a
respective first wellhead arrangement 151-154, a respective low
pressure compressor 141-144 is installed. Each low pressure
compressor 141-144 may increase the pressure from approximately 1
to 4 bars to approximately 5 to 20 bars.
[0052] By controlling the low pressure compressor 141-144, the mass
flow of gas that is delivered by a respective wellhead arrangement
151 to the gas input 101 is adjustable. The mass flow control unit
120 is adapted for controlling the respective low pressure
compressors 141-144 individually, so that each low pressure
compressor 141-144 may deliver a predetermined input mass flow {dot
over (m)}.sub.1 of gas to the gas input 101. The mass flow control
unit 120 is adapted, for example, for controlling the rotational
speed of each low pressure compressor 141-144.
[0053] In the exemplary embodiment shown in FIG. 1, four low
pressure compressors 141-144, four wellhead arrangements 151-154
and four delivery valves 161-164 are shown. In other exemplary
embodiments, more or fewer low pressure compressors 141-144,
wellhead arrangements 151-154 and delivery valves 161-164 may be
installed.
[0054] A gathering group may be formed by one low pressure
compressor 141-144, one wellhead arrangement 151-154 and one
delivery valve 161-164. Each gathering group is coupled to a
respective borehole. All gathering groups deliver gas to a common
collecting manifold to which the high pressure compressor 100 is
coupled. A gas field may include a plurality of boreholes. A
respective gathering group is coupled to each borehole.
[0055] The system may also include a further high pressure
compressor 100. First gathering groups are connected to the one
high pressure compressor 100, and second gathering groups are
connected to the further high pressure compressor.
[0056] The high pressure compressor 100 is adapted for increasing
the received gas at the gas input 101 from approximately 10 to 14
bars to approximately 60 to 90 bars at the gas outlet 102. For the
gas export system 130, a high gas pressure that is needed, for
example, for the further processing of the gas is provided.
[0057] As shown in FIG. 1, the system includes a return flow tubing
103 to which a bleeder valve 104 is connected. The bleeder valve
104 is controlled by the mass flow control unit 120. If the
measured input mass flow {dot over (m)}.sub.1 is lower than the set
point input mass flow, the mass flow control unit 120 controls the
bleeder valve 104 such that a part of the gas is bled off from the
gas outlet 102 and injected into the gas input 101, such that the
input mass flow value is increased until the input mass corresponds
to the set point input mass flow value.
[0058] The term "including" does not exclude other elements or
steps, and "a" or "an" does not exclude a plurality. Also, elements
described in association with different embodiments may be
combined.
[0059] It is to be understood that the elements and features
recited in the appended claims may be combined in different ways to
produce new claims that likewise fall within the scope of the
present invention. Thus, whereas the dependent claims appended
below depend from only a single independent or dependent claim, it
is to be understood that these dependent claims can, alternatively,
be made to depend in the alternative from any preceding or
following claim, whether independent or dependent, and that such
new combinations are to be understood as forming a part of the
present specification.
[0060] While the present invention has been described above by
reference to various embodiments, it should be understood that many
changes and modifications can be made to the described embodiments.
It is therefore intended that the foregoing description be regarded
as illustrative rather than limiting, and that it be understood
that all equivalents and/or combinations of embodiments are
intended to be included in this description.
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