Short-range wireless sensor networks for high density seismic monitoring

Acquisition systems for sub-surface diagnostic (for small earthquake monitoring) and exploration (for new oil and gas reservior) require a large number of sensors (geophones or accelerometers) to be deployed in outdoor over large areas to measure backscattered wave fields. A storage/processing unit (sink node) collects the measurements from all the geophones to obtain an image of the sub-surface for real-time analysis of seismic activity. In-depth imaging quality depends on the number of sensors deployed and on the position accuracy for each sensing device. Current connectivity is cable based and in some cases requires hundreds of kilometers of cabling while synchronous acquisition is obtained thorugh GPS causing large power consumption and degradation in accuracy. Replacing cables with wireless connectivity to create a wireless geophone network (WGN) is now becoming attractive to improve the monitoring quality and enable synchronous monitoring (and self-localization) with minimal use of GPS. This paper serves as a tutorial to introduce the basic principles of seismic monitoring systems from a wireless communication perspective. Specifications for the network architecture and the MAC layer are proposed to replace the actual cabled systems.