SPE Projects, Facilities & Construction
Volume 6,
Number 4,
December 2011,
pp. 179-184
Summary
The knowledge in real time of the concentration fields resulting from the
accidental release of a hazardous substance would be extremely valuable
information as support for emergency actions and for impact evaluation on the
industrial site itself and its vicinity. For that purpose, a modeling platform
is being developed and applied to simulate in real time the atmospheric
dispersion of a hazardous substance at the scale of the industrial site and
also of its surroundings. The industrial site of Lacq (France) has been chosen
as a pilot, and the key hazardous substance considered in this study is
hydrogen sulfide (H2S). A 3D computational-fluid-dynamic (CFD) model
(Fluidyn-Panepr) has been chosen to simulate the 3D wind-field pattern on the
industrial site, taking into account the details of the installations. This
approach enables a simulation as close as possible of the turbulence and flow
around the buildings that could not be achieved with a standard Gaussian
approach. For that purpose, a detailed numerical model of the Lacq installation
was built on the basis of a thorough review of the existing installations and
an evaluation of their size and "porosity." Wind fields were calculated for a
set of predefined boundary conditions based on the climatology of the site.
Investigations were carried out to ensure that site information systems could
deliver the information available from the H2S sensors and on-site
meteorological station in real time. The real-time approach is made possible by
the use of a complete wind-field precalculated database automatically selected
in case of accidental release by comparison with real-time wind-direction and
-speed measurements from the meteorological station located on the industrial
site. The location and intensity of the source term are determined using a
probabilistic approach (Bayesian inference), making use of both real-time
measurements and precalculated concentration responses from unitary emissions
(puffs) on sensors. This approach was validated successfully using a limited
number of sensors and sources but with the complex structure and flow patterns
expected on the site. The activation of the simulation platform is triggered by
the detection of threshold concentrations at the sensors. The estimated source
term is then used in forward dispersion mode to simulate the dispersion in
(fast) Lagrangian puff mode. The modeling platform will be validated through
measurement campaigns with a neutral species in 2010.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
6 October 2009
- Meeting paper published:
8 December 2009
- Revised manuscript received:
25 September 2010
- Manuscript approved:
30 November 2010
- Published online:
21 October 2011
- Version of record:
16 December 2011