Method and device intended for seismic exploration of an underwater subsurface zone using seismic receivers coupled with the water bottom

A system for seismic exploration of an underwater subsurface formation comprising:

• a displaceable collecting assembly which moves under water and is deployed under water to collect data and includes a recording unit;
• at least one seismic signal acquisition unit including a spire associated with housing containing at least one seismic receiver which collects seismic signals sensed by the at least one seismic receiver, the spire leading the acquisition unit downwards solely under an effect of gravity to the bottom of the water body and driving the spire therein to couple the at least one acquisition unit with the subsurface formation;
• an acoustic transponder associated with the at least one acquisition unit;
• an acoustic ranging assembly which communicates with the at least one seismic signal acquisition unit and provides a reference for obtaining a position of each acquisition unit on the bottom of the water body;
• and
• a data link which transmits seismic data between the at least one acquisition unit and the recording unit which records the data when the displaceable collecting assembly is deployed under water to collect data.

A method of seismic exploration of an underwater subsurface formation, comprising:

• installing at a bottom of a water body at least one seismic signal acquisition unit including at least one seismic receiver including a data acquisition module for collecting seismic signals sensed by the at least one seismic receiver and an acoustic transponder coupling the at least one seismic receiver to the formation;
• determining a position of each acquisition unit installed at the bottom of the water body with respect to an acoustic ranging assembly which communicates with the at least one seismic signal acquisition unit and provides a reference for obtaining a position of the at least one seismic acquisition unit which is obtained with a satellite positioning system;
• carrying out seismic operations with transmission of seismic waves by an underwater seismic source to the subsurface formation and receiving waves with the at least one receiver reflected by discontinuities of the subsurface formation in response to the transmission of seismic waves to the subsurface formation and collecting seismic data with the data acquisition module of the at least one acquisition unit;
• and
• recovering at the surface of the water body the seismic data collected by the at least one acquisition unit using a recording unit associated with a displaceable collecting assembly which moves under the water and is deployed under the water to collect seismic data while an acoustic or optical transmission link transmits seismic data collected by the at least one acquisition unit to the recording unit which records the seismic data.