An uncoupled acoustic sensor for land seismic acquisition

Current seismic acquisition systems support over 100, 000 channels, and new ones are expected to exceed 1 million channels. The related challenges include not only data storage and processing, but also the field logistics, their main task being the data collection employing ever larger number of sensors. A major factor affecting both cost and quality of land seismic surveys is the need of planting and retrieving the sensors. This operation is manpower intensive, and it can be particularly expensive in hostile environments as those found in the Middle-Eastern deserts or the Arctic regions. In these areas, additional challenges are provided by the poor sensor to ground coupling in loose soils like sand dunes or soft snow. Hard and often rough surfaces found, for example, on carbonates outcrops or the impenetrable permafrost can be detrimental to obtaining good coupling. Surface-consistent corrections and near surface imaging exploiting data redundancy compensate only partially the effect of sensor footprint. Therefore, to overcome the above drawbacks it is desirable to provide sensors that require no coupling to the ground. The uncoupled acoustic sensor described herein consists of an ultrasonic transmitting-receiving system for accurate measurements of nano-vibrations of the earth surface by means of Doppler shift.