(27f) Flammable Gas Dispersion in Offshore Platforms: Gas Detectors Location

Oil exploration and production activities in offshore structures always have the risk associated to the leaks of flammable gases. Those gases in near stoichiometric mixtures with air can suffer ignition, causing accidents with explosions that may result in injuries to people, to installations, to the environment and even to the image of the company. The P-36 in 2001, Campos Basin and the Piper Alpha in 1988, North Sea, are examples of accidents in maritime platforms with explosions and victims. Thus, detection systems of flammable gases must be considered during the offshore platforms design. Those systems are generally based on technical norms that do not supply all the necessary information to determine the best number and location of the detectors. Therefore, there is a possibility of both cost increases due to an overestimated number of sensors or accidents due to lack of these sensors. In this work, Computational Fluid Dynamics (CFD) was used to predict gas plumes developments, and then, applying a methodology based on the risk due to each leak was used to find the best position and the number of detection points. The numerical simulations were carried out taking in account the region meteorological conditions. A typical platform layout was used in the simulations and the compression section was selected for the case study. One point of leakage in six orthogonal directions was employed. Each one of these six directions was submitted to eight distinct wind directions. Based in this case study, it is believed that this methodology is a useful tool to evaluate and to improve the project of the flammable gases detection system in the entire platform.