SYSTEM AND METHOD FOR SUPPLYING NATURAL GAS TO A SALES LINE

SYSTEME ET PROCEDE POUR FOURNIR DU GAZ NATUREL A UN POINT DE VENTE

English Abstract

A system is disclosed for supplying natural gas to a sales line, the system comprising: an inlet connected to receive natural gas from a well; an outlet connected to discharge the natural gas to a sales line; piping between the inlet and the outlet; a moisture sensor on the piping for detection of a predetermined moisture level in the natural gas; a shutdown valve, on the piping, connected to close upon detection by the moisture sensor of a moisture level at or above the predetermined moisture level; an odorant addition unit on the piping; and a gas analyzer on the piping for tracking the volume and heating value of natural gas discharged through the outlet. A method of supplying natural gas to a sales line is also disclosed.

French Abstract

Le système décrit est destiné à alimenter en gaz naturel un circuit de distribution commercial. Le système comprend une entrée raccordée pour recevoir du gaz naturel provenant dun puits, une sortie raccordée pour décharger le gaz naturel vers un circuit de distribution commercial, une tuyauterie entre lentrée et la sortie, un capteur dhumidité sur la tuyauterie pour la détection dun niveau dhumidité prédéterminé dans le gaz naturel, une vanne darrêt, sur la tuyauterie, raccordée pour se fermer lors de la détection par le capteur dhumidité dun niveau dhumidité égal ou supérieur au niveau dhumidité prédéterminé, une unité dajout de substance odorante sur la tuyauterie, et un analyseur de gaz sur la tuyauterie pour assurer le suivi du volume et du pouvoir calorifique du gaz naturel déchargé par la sortie. Un procédé dalimentation en gaz naturel dun circuit de distribution commercial est également décrit.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A system for supplying natural gas to a sales line, the system comprising:
an inlet connected to receive natural gas from a well;
an outlet connected to discharge the natural gas to a sales line;
piping between the inlet and the outlet, the piping including a check valve
and a hydrogen
sulfide sensor;
a separator on the piping for at least partial removal of liquids and solids
from the natural
gas;
a heater connected to receive natural gas from the piping;
a moisture sensor on the piping for detection of a predetermined moisture
level in the
natural gas;
a shutdown valve, on the piping, connected to close upon detection by the
moisture
sensor of a moisture level at or above the predetermined moisture level;
an odorant addition unit on the piping;
a gas analyzer on the piping for tracking the heating value of natural gas
discharged
through the outlet, the gas analyzer comprising a cylinder that may be removed
from the gas
analyzer for use in determining compensation for the natural gas discharged
through the outlet;
an instrument gas takeoff, connected to receive natural gas from the piping to
supply
instrument pressure to the shutdown valve;
a meter for tracking the volume of natural gas discharged through the outlet;
a controller connected for controlling operation of the moisture sensor, the
shutdown
valve, the odorant addition unit, and the gas analyzer; and
in which the system is configured to be portable on wheels or a skid, and the
heater,
moisture sensor, shutdown valve, odorant addition unit, gas analyzer, and
instrument gas takeoff
are contained within a housing mounted on the wheels or skid.
2. The system of claim 1 in which the heater is a catadyne heater.
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3. The system of claim 1 or 2 located at a well site, the sales line is
connected to supply
natural gas to one or more buildings and further comprising a bypass on the
piping for bypassing
the gas analyzer and the odorant addition unit.
4. The system of claim 3 in which the separator comprises a Y strainer.
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Description

SYSTEM AND METHOD FOR SUPPLYING NATURAL GAS TO A SALES LINE
TECHNICAL FIELD
[0001] This document relates to systems and methods for supplying natural
gas to a
sales line.
BACKGROUND
[0002] Natural gas produced from a well is sent downstream to a processing
facility
such as a refinery, ultimately being discharged into a sales line after
processing for
distribution to consumers.
SUMMARY
[0003] A system is disclosed for supplying natural gas to a sales line,
the system
comprising: an inlet connected to receive natural gas from a well; an outlet
connected to
discharge the natural gas to a sales line; piping between the inlet and the
outlet; a moisture
sensor on the piping for detection of a predetermined moisture level in the
natural gas; a
shutdown valve, on the piping, connected to close upon detection by the
moisture sensor of a
moisture level at or above the predetermined moisture level; an odorant
addition unit on the
piping; and a gas analyzer on the piping for tracking the volume and heating
value of natural
gas discharged through the outlet.
[0004] A method is also disclosed of supplying natural gas to a sales
line, the method
comprising: supplying natural gas from a well into piping that discharges into
a sales line;
monitoring the moisture level of natural gas in the piping; opening a shutdown
valve on the
piping when the moisture level is below a predetermined moisture level; adding
odorant to
natural gas in the piping; tracking the volume and heating value of natural
gas discharged
from the piping into the sales line.
[0005] These and other aspects of the device and method are set out in the
claims.
BRIEF DESCRIPTION OF THE FIGURES
[0006] Embodiments will now be described with reference to the figures, in
which
like reference characters denote like elements, by way of example, and in
which:
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[0007] Fig. 1 is a schematic of a system for supplying natural gas to a
sales line.
[0008] Fig. 2 is a flow diagram of a method of supplying natural gas to a
sales line.
DETAILED DESCRIPTION
[0009] Immaterial modifications may be made to the embodiments described
here
without departing from what is covered by the claims.
[0010] Referring to Fig. 1, a system 10 for supplying natural gas to a
sales line 12 is
illustrated. System 10 comprises an inlet 14, an outlet 16, piping 18 between
the inlet 14 and
outlet 16, a moisture sensor 20, a shutdown valve 22, an odorant addition unit
24, and a gas
analyzer 26. Inlet 14 and outlet 16 may comprise respective valves 28. Inlet
14 is connected to
receive natural gas from one or more wells 30. Outlet 16 is connected to
discharge the natural
gas to sales line 12. Moisture sensor 20 is on the piping 18 for detection of
a predetermined
moisture level, such as a maximum moisture content in the natural gas as set
by regulation for
supply of natural gas to one or more buildings 32. Shutdown valve 22, which
may be an
emergency shutdown valve (ESD) as shown, is on the piping 18 and is connected
to close
upon detection by the moisture sensor 20 of a moisture level at or above the
predetermined
moisture level. Odorant addition unit 24 is on the piping 18, and may further
comprise an
odorant source 34, one or more lines 36 to piping 18, and an orifice plate 38,
the combined
function of which is known in the industry for dispensing controlled amounts
of scent or odor.
Odorant source 34 contains one or more suitable odorants, such as t-butyl
mercaptan,
thiophane, ethyl mercaptan, dimethyl sulfide, or other odorants as required by
regulation or as
desired. Gas analyzer 26 is on the piping 18 for tracking the heating value of
natural gas
discharged through the outlet 16. Gas analyzer 26 may further comprise a
sampler 42, which
may further include a sample storage apparatus such as a cylinder 44. Volume
meter 40 is on
the piping 18 for tracking the volume of natural gas discharged through the
outlet 16. Meter
40 may include a correction device (not shown). The cylinder 44 is an example
of one or
more parts that may be removed from the gas analyzer 44 for use in determining
compensation for the natural gas discharged through the outlet 16. For
example, sampler 42,
such as a DYNAPAKTM sampler may take a
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predetermined size of sample at a predetermined time interval, and store the
sample in
cylinder 44 for later analysis. Periodically, cylinder 44 may be removed from
system 10 and
analyzed to determine the average heating value of the natural gas contained
within the
cylinder. The average heating value may then be used with the flow data from
meter 40 to
determine the estimated total value of the natural discharged into the sales
line 12 for the
purpose of billing a customer such as a natural gas distributor for the cost
of the natural gas
received in sales line 12. Sales line 12 may be a suitable commercial gas line
that might be
supplying a house or community with natural gas.
[0011] Other
components may be present. System 10 may further comprise a natural
gas powered generator (not shown), connected to receive natural gas from the
piping 18 to
supply power to one or more of the moisture sensor 20, the shutdown valve 22,
the odorant
addition unit 24, and the gas analyzer 26. The generator may also be used to
power any or all
of the system components that require power to operate. Other power sources
may be used.
An instrument gas takeoff 47 may be connected to receive natural gas from the
piping 18 to
supply instrument pressure to one or more system components, such as the
shutdown valve
22, which may require gas pressure to open and close. A catadyne heater 48 may
be
connected to receive natural gas from the piping 18. Heater 48 may be
advantageous in
colder climates or in areas where the nighttime temperature drop is sufficient
to warrant a
heater. A check valve 72 may be located on the piping 18 for ensuring one way
flow to outlet
16. A separator 60, such as a y strainer as shown or a filter, may be on the
piping 18 for at
least partial removal of liquids and solids from the natural gas. Separator 60
may comprise a
dryer (not shown) in some embodiments. A hydrogen sulfide sensor 66 may be on
the piping
18. A bypass 68 may be on the piping 18. Bypass 68 may bypass one or more
system
components, such as the gas analyzer 26 and the odorant addition unit 34 as
shown. Bypass
may allow work to be done on system 10 without disrupting the flow of gas
through piping
18. One or more valves (not shown) may be provided to operate bypass 68 as
desired.
Various fittings, regulators, piping, and other components not shown may be
required to
implement system 10. One or more of inlet 14 and outlet 16 may tie in to a
respective
compressor (not shown) for assisting transport to piping 18 or sales line 12.
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[0012] System 10 may further comprise a controller 62 connected to one or
more
system components, such as one or more of the moisture sensor 20, the shutdown
valve 22,
the odorant addition unit 24, and the gas analyzer 26. In the example shown,
controller 62 is
connected by control lines 64A-G to moisture sensor 20, sampler 42, odorant
addition unit
24, meter 40, shutdown valve 22, heater 48, and H2S sensor 66, respectively.
Other
components such as valves 28 and 72 may be connected to controller 62.
Controller 62 may
be adapted to store information, such as if controller 62 comprises a computer
data storage
medium for storing data from sensors in the system 10. Controller 62 may also
be adapted
transmit information, for example through a wired or wireless modem (not
shown) to a
remote site. Controller 62 may be operated on site or by remote. Controller 62
may be
powered by one or more suitable power source such as a generator or one or
more solar
panels (not shown). Controller 62 may be a supervisory control and data
acquisition
(SCADA) system.
[0013] System 10 may be located at a well site, for example with inlet 14
connected
to a production line 70 from one or more wells 30. System 10 may be a portable
system
designed to shunt natural gas, such as unprocessed natural gas, from transit
to a refinery or
other process equipment if the natural gas is of sufficient quality for supply
to a sales line.
Thus, system 10 is able to take advantage of the presence of produced gas of
high quality by
avoiding sending such gas through the unnecessary and costly step of
processing in a
refinery. System 10 may also be designed to run automatically, such that
system 10 provides
an automatic diverter for such gas, requiring little attention other than
periodic visits to
obtain flow meter information and to replace cylinder 44 in one embodiment.
System 10 may
also be portable, for example if system 10 is located on wheels or a skid (not
shown) for ease
of transport to a suitable location. System 10 may include a protective
housing (not shown),
such as a shed for containing the components of system 10. Additional space
may be
provided in the housing for allowing a user to perform maintenance or
otherwise access
system 10 while avoiding the conditions of the external environment. System 10
may also be
located at a distance from the well 30, for example along piping (not shown)
to a refinery.
[0014] Referring to Fig. 1, the method shown in Fig. 201 supplying natural
gas to a
sales line 12 will now be described with reference to the method stages shown
in Fig. 2. In a
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stage 50, natural gas is supplied from a well 30 into piping 18 that
discharges into a sales line 12.
In a stage 52, the moisture level of natural gas in the piping 18 is
monitored. In a stage 54,
shutdown valve 22 on the piping 18 is opened when the moisture level is below
a predetermined
moisture level, such as the maximum moisture level as set by regulation or as
desired. If no
information is obtainable from sensor 20 for example due to malfunction, or in
the case of
detection of a component malfunction anywhere in system 10, system 10 may
respond by
shutting valve 22 to prevent further discharge of natural gas from outlet 16.
In a stage 56,
odorant is added to natural gas in the piping 18. In a stage 58, the volume
and heating value of
natural gas discharged from the piping 18 into the sales line 12 is tracked,
for example by
monitoring the volume of natural gas passing through the piping 18 with meter
40, and sampling
the natural gas with sampler 42 at predetermined intervals. The method may
include other stages
such as at least partially removing liquids and solids from the natural gas in
the piping 18 using
separator 60, monitoring the hydrogen sulfide level of natural gas in the
piping 18 with H2S
sensor 66, supplying natural gas to one or more buildings 32 from the sales
line 12, and
removing one or more parts such as cylinder 44 from the gas analyzer 26 and
using the one or
more parts for determining compensation for the natural gas discharged through
the outlet 16.
Suitable methods may incorporate other stages not discussed.
[0015] Although the system 10 illustrated in Fig. 1 shows a suitable layout
of
components, other arrangements may be used. For example, meter 40 may be
located
downstream of odorant addition unit 24. In addition, 112S sensor 66 may be
located before
shutdown valve 22 to provide earlier warning of the presence of unsuitable H2S
levels in the
natural gas. Other arrangements may be used.
[0016] In the claims, the word "comprising" is used in its inclusive sense
and does not
exclude other elements being present. The indefinite article "a" before a
claim feature does not
exclude more than one of the feature being present. Each one of the individual
features described
here may be used in one or more embodiments and is not, by virtue only of
being described here,
to be construed as essential to all embodiments as defined by the claims.
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Representative Drawing