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Remote Gas well sites require local flow metering of the mineral reserve's gas low rate for asset and revenue accounting purposes. Traditionally this was done using high maintenance mechanical circular chart recorders. Today these have been replaced with electrically powered RTUs, i.e., Remote Terminal Units.
Remote Gas well sites require local flow metering of the mineral reserve's gas flow rate for asset and revenue accounting purposes. Differential pressure [[flow meter]]s are commonly used for this purpose.<ref>{{citation|url=http://books.google.com/books?id=sarHIbCVOUAC|title=Instrumentation reference book|author=Walt Boyes|year=2003|isbn=9780750671231|page=9}}</ref>


Multiple remote terminal units communicate to a central Host system via radio systems or tap into the cellular phone system. The Host (or Central Control Room) c/w the RTUs and radio communication infrastructure is referred to as a SCADA system, i.e., Supervisory Control and Data Acquisition.
Traditionally, local flow metering was done using high maintenance mechanical circular [[chart recorder]]s. Today these have been replaced with electrically powered [[Remote Terminal Unit]]s (RTU). Multiple remote terminal units communicate to a central host system via [[radio]] systems or tap into the [[cellular phone]] system. The host (or Central Control Room) communicates with the RTUs and radio communication infrastructure is referred to as a [[SCADA]] system, i.e., Supervisory Control and Data Acquisition.
In addition to [[gas flow computer|gas flow metering]], the RTU also provides some local, self-contained, site control such as well shut-in in the event of abnormal gas flow conditions. However the bulk of the RTU's function is to provide the host with site specific [[data]] which includes the above mentioned gas flow metering data, plus process related data including [[pipeline transport|pipeline]] and/or well pressure, [[natural gas condensate|condensate]] tank levels etc.


In addition to gas flow metering, the RTU also provides some local, self-contained, site control such as well shut-in in the event of abnormal gas flow conditions. However the bulk of the RTU's function is to provide the Host with site specific data which includes the above mentioned gas flow metering data, plus process related data including pipeline and/or well pressure, condensate tank levels etc.
===Not all RTUs are the same===
The distinguishing feature of the remote [[gas well]] RTU is a "[[gas flow computer]]". This is essentially a sophiscated subprogram or [[flow computer]] algorithm. The [[oil well]] RTU is much less complex since liquid oil flow metering is simpler. In the case of electrical utility RTU, there is a critical need for precise event time monitoring so that the first breaker to trip (closest to the fault) can be determined.
As these sites are remote such that utility electrical power is rarely available, the RTUs must be powered by an array of [[Photovoltaic module|solar panel]]s plus batteries. The batteries enable the RTU to continue to function when the sun is below the horizon or is obscured by heavy cloud cover. These RTUs also must be extremely rugged and energy efficient, i.e., must function to -35 °C. Energy efficient RTUs vastly reduce the cost of the solar battery system especially at higher latitudes.


[[Not all RTUs are the same]]..... The distinguishing feature of the remote gas well RTU is a "gas flow computer". This is essentially a sophiscated subprogram or flow computer algorithm. The Oil well RTU is much less complex since liquid oil flow metering is simpler. In the case of electrical utility RTU, there is no gas flow computer but there is a critical need for precise event time monitoring. Precise time monitoring enables a critical function of being able to determine the source of electrical outage, i.e., the first breaker to open is typically closest to the electrical fault. However downstream breakers may also trip a few milliseconds later.
==References==
{{reflist}}


As these sites are remote such that utility electrical power is rarely available, the RTUs must be extremely energy efficient, especially in the harsher weather northern latitudes. In most cases electric power is provided by an array of solar panels plus batteries so that the RTU can function through the night hours or long spells of heavy overcast.
[[Category:Energy development]]
[[Category:Telemetry]]

Latest revision as of 06:10, 6 June 2009

Remote Gas well sites require local flow metering of the mineral reserve's gas flow rate for asset and revenue accounting purposes. Differential pressure flow meters are commonly used for this purpose.[1]

Traditionally, local flow metering was done using high maintenance mechanical circular chart recorders. Today these have been replaced with electrically powered Remote Terminal Units (RTU). Multiple remote terminal units communicate to a central host system via radio systems or tap into the cellular phone system. The host (or Central Control Room) communicates with the RTUs and radio communication infrastructure is referred to as a SCADA system, i.e., Supervisory Control and Data Acquisition. In addition to gas flow metering, the RTU also provides some local, self-contained, site control such as well shut-in in the event of abnormal gas flow conditions. However the bulk of the RTU's function is to provide the host with site specific data which includes the above mentioned gas flow metering data, plus process related data including pipeline and/or well pressure, condensate tank levels etc.

Not all RTUs are the same

The distinguishing feature of the remote gas well RTU is a "gas flow computer". This is essentially a sophiscated subprogram or flow computer algorithm. The oil well RTU is much less complex since liquid oil flow metering is simpler. In the case of electrical utility RTU, there is a critical need for precise event time monitoring so that the first breaker to trip (closest to the fault) can be determined. As these sites are remote such that utility electrical power is rarely available, the RTUs must be powered by an array of solar panels plus batteries. The batteries enable the RTU to continue to function when the sun is below the horizon or is obscured by heavy cloud cover. These RTUs also must be extremely rugged and energy efficient, i.e., must function to -35 °C. Energy efficient RTUs vastly reduce the cost of the solar battery system especially at higher latitudes.

References

  1. ↑ Walt Boyes (2003), Instrumentation reference book, ISBN 9780750671231, http://books.google.com/books?id=sarHIbCVOUAC 
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