A simplified analysis of well blow-outs

摘要

A simplified method has been developed by TEA Group and ENI E&P for the complete characterization of atmospheric blow-outs. The core of the method is a zero-dimensional model of well flow. The model calculates the blow-out oil and gas flow rates; the throat pressure and temperature; the outlet gas velocity; the flow conditions at the outlet section (critical or subcritical); the fluid properties at the outlet during an atmospheric or underwater blow-out; the droplet size distribution at wellhead; the jet height and radius; the jet mean temperature; the air entrainment in the jet. These data allow a correct prediction of the gas/droplets dispersion and of the extension of the area affected by oil contamination. To this purpose droplet dispersion in the atmosphere is simulated with a ballistic approach. The model is able to consider a standard deviation on wind direction distribution, depending on meteorological conditions. This allows a soil contamination map to be derived. Gas dispersion is simulated with a Gaussian approach. The correlations adopted in the model for the simulation of well flow, for the droplet size distribution and for the jet parameters have been developed and validated with an experimental investigation carried out at TEA'S Laboratory.