ISO TC193 SC3 WG2
Wet Gas Flow Measurement
in Natural Gas Operations
Richard Steven, CEESI
Convenor of ISO TC193 SC3 WG2
Introduction
• ISO has finally developed a TR on wet natural
gas flow metering… and not before time!
• TC193 SC3 WG2 first met in 2007, TR will be
released Q2 2014 (estimated!)
• Why so long? - complexity & large scope
- politics!!
• 1st ISO review of the ‘state of the art’ of wet
natural gas metering.
• 100 pages long (approx), & detailed, to promote
the report I have chosen a few highlights.
Definitions
• Multiphase wet gas meter technology has over
the years developed its own ‘jargon’, i.e.
terminology.
• “It is impossible to disassociate language from
science...To call forth a concept, a word is
needed.” Lavoisier (father of modern chemistry)
• It is critical for industries understanding of
multiphase wet gas meter technology that this
jargon is agreed upon & defined.
• ISO TC193 has a comprehensive definitions
section.
What wet gas flow conditions covered?
The ISO TR text includes:
• Common measurement objectives:
e.g. well management, production optimisation,
allocation & flow assurance.
• Meter selection issues:
e.g. economic justification, lifecycle cost, issues
with intended location, physical limitations,
impact of changing fluid properties, etc.
• Varying meter output requirements:
e.g. meter gas flow only, meter liquid flow only,
meter gas & liquid flow OR gas, oil & water (
often for flow assurance purposes.)
The ISO TR Reviews / Explains the Main Generic
Methods of Wet Gas Flow Metering:
• Stand Alone DP Meters
Orifice Meter Example
Stand Alone DP meter with PPL Reading
DP meter with PPL Reading
Two Dissimilar Meters in Series
ISO Comments on These Three
Wet Gas Metering Methods
• These 3 relatively simple concepts are the
most widely used methods of wet gas metering
- however the devil is in the detail.
• Each method uses semi-empirical data fits, and
users extrapolate these at their own risk.
• The TR explains the publicly known abilities &
limitations of these wet gas metering methods.
• These methods may require dedicated meter
testing at a wet gas flow facility.
Multiphase Wet Gas Meters
• Meter all 3 phases!
• More sophisticated,
operational details are
typically confidential.
• lSO describes generic
concepts – and public
knowledge of operator
experience.
Generic Multiphase Wet Gas Meter
(Diagram is of a OneSubsea Phasewatcher)
Generic Multiphase Wet Gas Meter
•DP meter + Phase Fraction Device + ‘slip model’
(i.e. the confidential vendor calculations).
•Slip models are vendor confidential. ISO cannot
& does not disclose them – however, ISO offers
neutral advice from operator experience.
“In theory, there is no difference between
theory and practice. But, in practice, there is.”
van de Snepscheut
Comprehensive Subject Matter includes:
• Flow patterns & their influence on metering,
• Design & installation considerations,
• Testing, verification & calibration,
• Common field challenges, &,
• Operation & field verification, such as…
system redundancy and diagnostics
Example 1:
Dual instruments & system redundancy…
• Example 2: DP meter diagnostics system to
confirm integrity of DPs read + DP redundancy
Petronas wet gas
Venturi meter with
‘Prognosis’ under
test at CEESI wet
gas facility.
Conclusions
• Industry increasingly requires wet gas meter
technologies… but wet natural gas metering
technology is complex & varied.
• ISO TC193 has developed a TR written by a
cross section of operators, test facilities, meter
manufacturers and consultants.
• It is hoped that industry will find this TR’s
content to be a valuable and timely addition to
the wet gas meter knowledge base, and that it
will be widely used in industry.