Shark Attack on Streamer Cables

Abstract

In search of new subsea oil fields through marine seismic surveys, WesternGeco faces an issue which causes extensive losses and delays. Due to the magnetic field exerted from the streamer cables, sharks (bull sharks in particular) become attracted to the area of operation. In some regions equipment loss caused by sharks biting the streamer cables has become a major problem. The objective for this master thesis, are therefore to investigate the response of the streamer cables when subjected to a typical shark attack.

In order to generate a representative CAD- and FE-model of a shark jaw for simulation purposes, an authentic bull shark jaw was acquired and 3D-scanned. The shark jaw were converted to a CAD-model utilizing reverse engineering applications. Numerical models of the streamer cables, capturing the response with respect to friction properties and failure criteria s, have been benchmarked by means of quasi-static compression tests. Additionally, dynamic simulations replicating the shark attack on streamer cables has been conducted. Incorporating reasonable values with respect to bite force and kinematics, documented in available research concerning biomechanics of sharks.

Based on the results from the physical quasi-static compression tests, it is reasonable to conclude that the FE-models of the streamer cables are valid. In regards of the streamer cables resilience towards shark bite. The results from the dynamic analyzes prove that the isolated shark bite mechanism alone, is not sufficient to inflict a critical damage on the streamer cables. On this note it is concluded that the bite resilience of the streamer cable is strongly correlated to the shark speed upon impact.