Measurements of underwater radiated noise from mobile offshore drilling units (PDF)

Austin, M.E., S.B. Martin, C.R. McPherson

The Effects of Noise on Aquatic Life (2023)

DOI: 10.1007/978-3-031-10417-6_7-1

Mobile offshore drilling units (MODUs) are used to drill oil and gas wells in the ocean. For deeper water operations, there are two common forms of MODUs: semisubmersible rigs and drillships. Over the past several years, JASCO Applied Sciences measured MODU drilling operations by semisubmersibles and drillships, including platforms that were moored with anchors or that held position using dynamic positioning (DP) thrusters. The MODUs were accompanied by support vessels on standby, with additional vessels conducting resupply operations during the drilling campaigns. The measurements were performed in response to regulators requesting verification of the vessel source levels and the distances where the sounds were expected to either injure or disturb marine life.

Overall, drillships had higher source levels than semisubmersibles. Moored platform sound levels decreased with drilling depth and hole diameter. The signatures of moored platforms featured tones from different types of rotating machinery. When platforms or nearby support vessels were holding station using DP, the tonal signatures were obscured by DP thruster sounds. All measurements of underwater radiated noise from platforms using DP contained sounds from ultrashort baseline (USBL) beacons at 25–27 kHz.