Atmospheric dispersion analysis uses calculations and/or simulations to predict the propagation of gas clouds from a blowout, leak, or flare. Gaussian plume analysis or computational fluid dynamics are used to determine the concentration of flammable or toxic gases from the source as gas is dispersed by wind and atmospheric turbulence. Wind speed, temperature, humidity, and atmospheric stability are accounted for in the analysis as is the presence of terrain and surrounding structure if required. Results from the analysis can be used in the planning safe zones and exclusion zones for well control operations, relief well operations, and overall risk of exposing the surrounding areas to the gas cloud.
The accidental or controlled release of hydrocarbon gas or other pollutants, either from a well or production equipment, can lead to the formation of an explosive or toxic cloud in the atmosphere, putting personnel, equipment, and potentially the wider public at risk. Understanding the size and extent of the gas cloud generated by such releases is an important part of understanding the risk associated with the event.
Whether the ignition is planned or accidental, the igniting of a flammable or toxic cloud leads to the additional problem of radiant heat. This poses a threat to people and equipment and, therefore, also needs to be quantified to determine whether risks are acceptable.