Proximate Measurements of Acoustic Emissions Associated with the Installation and Operation of an Exploration Jackup Drilling Rig in the North Sea

Abstract

Underwater sound recordings were obtained from the Noble Kolskaya jackup gas-exploration drilling rig in the North Sea on the Dogger Bank. The aim was to document received levels, characteristics, and range dependence of sounds produced by the rig’s site installation and drilling during the winter. Sound pressure levels (SPLs) generated by the Kolskaya were similar to previous measurements from metal-legged bottom-founded rigs both in level (120 dB re 1 μPa) and in frequency range of dominant tonalities (2-1,400 Hz). Received levels were highly variable over short periods and generally varied by 15-20 dB between quietest (holding) and loudest (drilling) operations. The rig was significantly quieter than its associated support vessels at low frequency, although radiated noise levels were higher above 2 kHz. Rig high-frequency SPLs dropped rapidly above 8 kHz. Noise is discussed with reference to the hearing capabilities of the harbor porpoise (Phocoena phocoena).