Assessment of blowout rate and composition is a key issue for decision
s concerning blowout control method, design of kill operations, determ
ination of direct (e.g., environmental) and indirect (loss of reserves
) damage, etc. Usually, loss of control over the outflow of the well i
mplies that the blowout rate cannot be established with conventional m
eans. Experience shows that, because of the large reservoir decompress
ion, production well performance cannot be extrapolated reliably to bl
owout conditions. Hence, surface (simple) observations, such as wellhe
ad/drillpipe pressure and temperature, effluent shape and size and noi
se field, results of previous kill attempts, and pressure response of
nearby wells have to be interpreted in terms of the blowout rate. This
paper presents two examples of blowouts for which the combination of
such data led to a consistent and accurate picture of blowout well per
formance; it also describes how such estimates contributed to decision
s concerning the kill strategy, leading to success in a relatively sho
rt time.