HYDROCARBON
ENGINEERING
57
THE
ACT OF
AUDITING
H
ydrocarbon production is a complex and
technically challenging process. At each stage in
the process between extraction and refining,
accurate process monitoring and flow
measurement is critical. This is especially true in the custody
transfer of hydrocarbons between transport and storage
facilities, where measurement accuracy is at a premium.
In 2016, with an oil price at around US$40/bbl, and with
daily sales in the region of 100 million bbls, this would raise
US$4 billion/d in revenue. If one accepts that the uncertainty
in fiscal measurement was
±
0.25%, the resulting daily financial
exposure would be about US$10 million. This equates to an
exposure of US$3.6 billion/y, or nearly a day’s production.
In this sense, flow measurement systems can be
thought of as ‘cash registers’. As well as the financial risk
that can be incurred through mismeasurement, operating
companies need to know the nature of oil and gas
produced, as well as the level of contaminants in it, such as
produced water, sand and waxes. In addition, most
production areas worldwide have developed legislation
that limits the amount of waste introduced into the
environment.
In order to ensure measurement accuracy, flow meters
are normally calibrated at a specified frequency to
counteract errors caused by a range of factors, such as meter
fouling, erosion and mechanical wear. However, calibration
Neil Bowman, NEL, UK,
explains how hydrocarbon
transport and storage facilities can reduce financial
exposure through effective auditing of flow
measurement systems.
