Ocean Bottom Seismometer: Design and Test of a Measurement System for Marine Seismology

Abstract

The Ocean Bottom Seismometer (OBS) is a key instrument for the geophysical study of sea sub-bottom layers. At present, more reliable autonomous instruments capable of recording underwater for long periods of time and therefore handling large data storage are needed. This paper presents a new Ocean Bottom Seismometer designed to be used in long duration seismic surveys. Power consumption and noise level of the acquisition system are the key points to optimize the autonomy and the data quality. To achieve our goals, a new low power data logger with high resolution and Signal–to-Noise Ratio (SNR) based on Compact Flash memory card is designed to enable continuous data acquisition. The equipment represents the achievement of joint work from different scientific and technological disciplines as electronics, mechanics, acoustics, communications, information technology, marine geophysics, etc. This easy to handle and sophisticated equipment allows the recording of useful controlled source and passive seismic data, as well as other time varying data, with multiple applications in marine environment research. We have been working on a series of prototypes for ten years to improve many of the aspects that make the equipment easy to handle and useful to work in deep-water areas. Ocean Bottom Seismometers (OBS) have received growing attention from the geoscience community during the last forty years. OBS sensors recording motion of the ocean floor hold key information in order to study offshore seismicity and to explore the Earth’s crust. In a seismic survey, a series of OBSs are placed on the seabed of the area under study, where they record either natural seismic activity or acoustic signals generated by compressed air-guns on the ocean surface. The resulting data sets are subsequently used to model both the earthquake locations and the crustal structure.

Modeling and Research on Power System of Distributed Sensor Networks for Long Streamers in Marine Seismic Exploration

“…The sensors include piezoelectric ceramic sensors and microelectro mechanical systems (MEMS) sensors, which receive seismic wave signals reflected by the strata. Large-scale sensor networks and poor working conditions at sea necessitate a system with a convenient and stable power supply [13][14][15]. Most of the exploration instruments on the market adopt a daisy chain structure to transfer high voltage to single nodes.…”

Development of a Prototype Data Logger System to Operate under Extreme High Pressure

“…Thus, data loggers should be employed with subsea oil production systems. Data logger systems have been widely used to collect various types of data from the environment, sensors, and equipment [7][8][9][10]. However, data logger systems have not been widely used with subsea oil production systems because most experts have held the view that applying verified equipment and strict rules guarantees the safety of subsea production systems and that operation of subsea data logger systems and remotely operated vehicles (ROVs) for IRM result in additional operational costs.…”

In Design of an Ocean Bottom Seismometer Sensor: Minimize Vibration Experienced by Underwater Low-Frequency Noise

“…Therefore, the OBSs can process the inversion method for exploration of seafloor internal structures and stratum resolution enhancements. For this particular reason, they have been extensively employed in geophysical investigations, detection of natural earthquakes, and offshore oil and gas explorations [ 2 , 3 , 4 , 5 ].…”