Underwater sound radiation from subsea factories

In the oil & gas industry there is a trend towards more subsea activities such as the processing of the Oil and Gas in so-called 'subsea factories'. Regulations aimed at managing the impact of underwater sound on marine life are being put in place by different nations. Many offshore operations require an assessment of the potential impact of underwater noise on the environment, which requires knowledge of the sound transmitted by the subsea components. However, until now little is known about the underwater source mechanisms, the acoustic strength of these complex installations, the coupling of the emitted source sound to the surrounding medium and the impact of the sound on the underwater wildlife. With the measured noise spectrum in air) of a complete turbo compressor installation and correcting for the differences between radiation into air and sea water, a stylized, equivalent noise source power spectrum is constructed. Steps towards validation of the radiation correction are in progress. The contribution of the source to the subsea soundscape is computed by coupling the source model to an acoustical propagation model. Predicted levels can be used as an input for environmental impact studies. In water source and radiated sound levels are presented in this paper. The accuracy of the in air to underwater conversion methodology is discussed and knowledge gaps are identified. The high speed turbo compressor dominates the broadband sound pressure levels generated by the total subsea processing factory. Subsea processing sound exceeds the sound from a ship, especially is shallow water and for calm sea states due to the high frequency content of the subsea processing sources. The sound field of the compressor contains almost all of its energetic content above 1000 Hz, while for example ship generated sound is typically below 500 Hz. Copyright 2016, Society of Petroleum Engineers.