Practical Study of Toxic Gas Emergency Blowout and Dispersion. Dr. A. Yedigarov, Prof. G. Odisharia, Dr. V. Safonov (Research Institute of Natural Gases & Gas Technology), Dr. A. Shvyryaev (Lomonosov Moscow State University) 142717, Russia, Moskovskaya obl., Leninsky raion, p. Razvilka, VNIIGAS, Fax: 7-095-399-16-17
The paper presents computer study of sour gas accidental
releases from wells and pipelines. The main purpose of the study
was to understand risk associated with the exploration of sour
gas field in Russia and predict probable hazardous zones resulting
from accidental releases of sour gas in the atmosphere. Correct
solution of this problem requires first of all an implication
of the approved model of toxic gas dispersion. An original jet-diffusion
computer model was developed for the description of the interaction
between sonic or subsonic gas blowouts and atmospheric wind, turbulent
mixing, and heat-mass exchange in jet flow. The proposed K -
theory model assumes numerical solution of two-dimensional finite-differential
equations of turbulent flow and dispersion of binary, viscous,
heat conductive gas in the jet region of the flow, further transition
to the Gaussian model in trace diffusion region of the flow and
coinciding numerical and analytical solutions in the cross-section
of the transition area. The verification of the jet-diffusion
model was accomplished by comparing the results of computations
to data from experimental studies on different types of jet streams:
submerged jets, vertical jet in the cross wind, tilted jets, heated
streams and jets of light gas. Real observations of sour gas
accidental blowouts from wells were also in a good agreement with
model prediction. Different scenarios of accidents were taken
into consideration for risk assessment of gas field. The calculations
were done for a wide range of sour gas emission rate changing,
wells and pipelines diameters. The computations made it possible
to determine probable hazardous zones and to estimate hazards
associated with the exploration of the sour gas field.