Application of quantitative Risk assessment for planning high sour wells or working in an H2S Field close to populated areas.

Abstract

Abstract H2S or Hydrogen Sulfite is an IDLH (Immediate Danger to Life and Health) poisonous gas and its exposure to humans leaves serious effects that could range from death to lasting physiological and neurological sicknesses. H2S gas is also odorless, colorless and heavier than air which makes detection by humans very difficult. H2S occurs naturally in most hydrocarbon bearing formations and could also be generated through well interventions like fracting and flooding. Oil and Gas companies typically plan for any potential H2S presence and leaks to protect their site employees and contractors. They use gas monitoring devices, supply breathing air to required personnel and provide emergency plans to evacuate or rescue personnel who are potentially exposed. One area of concern that is often being neglected is the protection of the community where the drilling occurs in highly populated area in the event of a gas release. As H2S gas leaks in the air, solar heating/radiative cooling determined by cloud coverage and latitude from the equator, wind speed and direction, surface roughness, terrain and height from the ground are all factors that will affect where the plume will be headed and whether it will reach a populated area with a concentration that is harmful to the community. In addition to the above factors, source elements like diameter, initial jet density, velocity, proximity, obstacles and fallouts are important to building the dispersion model and predicting the impact on the nearby community. The result of the study would determine an EPZ (Emergency Planning Zone) which allows us to implement monitoring, alarming and evacuation plans within the EPZ. This paper aims to discuss how to conduct dispersion modeling as quantitave risk assememnt method and provide recommendation on how to choose and run models in order to evaluate the risks and proactively implement emergency plans to protect the populated areas near H2S areas