US 5,706,250 AGranted

Seismic transmission method and system utilizing concentration units

AssigneeInstitut Francais du Petrole

InventorsJoseph Rialan, Christian Grouffal

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Abstract

Seismic data acquisition devices (BA) distributed in an exploration zone are divided into n groups (GA1 to GAn) and, therein, into sub-groups having each a specific frequency for communicating with a concentration unit (Ck) which is connected to a central station (1) through Hertzian channels or cables or optical fibers. Acquisition devices in the various subgroups communicate simultaneously with the corresponding concentration unit (Ck) during predetermined emission windows. The concentration unit collects the signals received from the acquisition devices to transmit them in series to station (1). The acquisition devices are adapted for delaying their own emission window according to the rank which has been previously assigned thereto within the respective subgroups thereof.

Claims19

Dependent claims

A method of transmitting digitized data stored in a plurality of seismic data acquisition devices distributed in an acquisition zone produced from seismic signals transmitted through a subsoil of a geological formation containing discontinuities from a number of concentration units to a control and recording station comprising:

dividing at least part of the acquisition devices into groups with a number of the groups being at least equal in number to the number of concentration units with each group including a number of acquisition devices;
assigning to each group a number of radio transmission frequencies with the assigned number of radio transmission frequencies being less than the number of acquisition devices and defined for each group, the acquisition devices of each group being associated with a different one of the concentration units and having a transmitting device operating on at least one of the assigned number of transmission frequencies;
subdividing each group into at most the assigned number of subgroups of acquisition devices utilizing identical transmission frequencies and assigning different serial numbers to the acquisition devices of each subgroup;
sending a transmission order from the control and recording station to all of the concentration units and the acquisition devices to request transmission of signals;
and
transmitting signals successively from all of the acquisition devices of one of the subgroups with each signal being within an emission window staggered from other emission windows used to transmit other of the successive signals with each emission window being dependent upon the assigned serial number in the subgroup with the transmission of all of the subgroups being made during a subgroup transmission time interval.

3 more elements

A transmission system for transmitting digitized data stored in a plurality of seismic data acquisition devices distributed in an acquisition zone produced from seismic signals transmitted through a subsoil of a geological formation containing discontinuities from concentration units to a control and recording station comprising:

a number of concentration units with each concentration unit having a transmitting device for communication with the control and recording station and a radio transmitting and receiving set for communicating simultaneously on several frequencies with a group of the acquisition devices;
and
each acquisition device of the group having a storage of a serial number determining a priority rank of the acquisition device in a subgroup of the acquisition devices, a transmitting and receiving device which transmits on at least one radio transmission frequency, a decoder for decoding orders transmitted to the acquisition device from the control and recording station, a timing device for generating a time reference common to all of the acquisition devices of the group, and a processing device for determining an emission window for transmitting signals successively from all of the acquisition devices in the subgroup with the emission window of each of the acquisition devices being staggered from the emission window of the other acquisition devices in dependence upon the stored serial number.

Dependencies are inferred from the claim text.