MODELLING AND CONTROL OF TOWED MARINE SEISMIC STREAMER CABLES

摘要

Full-scale measurement data have revealed that slowly varying fluctuations in the course of survey vessels performing marine seismic data acquisition with towed recording (streamer) cables are capable of forcing the in-sea hardware in longitudinal and transverse directions. This may give rise to undesired low-frequency oscillations in the depth of streamer cables. The interaction between the transverse and longitudinal motions takes place at the location of the depth-control devices that are mounted along the streamers. A quasi-static model that describes the low-frequency dynamics of streamer cables is proposed for the purpose of controller design and analysis. The simulation study showed that the overall depth-control performance is sensitive to appropriate tuning of controller gains, selection of sampling period and application of dead bands. A successful depth control will rely on the number and lift capability of the mounted depth-control devices.