An electrical marine vibrator with a flextensional shell

Abstract

A completely new electro-mechanical marine Vibroseis concept is introduced that uses a flextensional shell with a uniquely developed form. Two controllable output resonances achieve a very high efficiency and repeatability, with a typical frequency bandwidth of 6?100 Hz. The marine vibrator can be used as a standard towed acoustic source in shallow water, or as a stationary source in transition zone environments. It is particularly significant that the vibrator requires only an electrical power supply, cannot leak hydraulic fluids, is easily transported, and is suitable for applications requiring very low environmental impact. A marine vibrator will provide several environmental advantages. Vibrator technology spreads the net source energy over a long period, reducing the acoustic power in comparison to impulsive sources. This is attractive for applications where high peak power may be problematic. This fact was established by the original hydraulic vibrators developed previously. An electrical marine vibrator offers even more advantages than hydraulic vibrators. There is no need for heavy equipment and hydraulic systems that can cause hydraulic oil spills. As the electrical vibrator requires only an electrical power supply it can be easily transported to different vessels and locations without any costly installations and potential environmental hazards. The marine vibrators discussed here have been tested as a standard towed acoustic source in shallow water, and as a stationary source in transition zone environments (4?6 ft of water). These applications are particularly well suited for this type of source.