Sensor array

Abstract

A sensor arrangement for monitoring a oil reservoir comprises a sensor array (1) comprising a plurality of sensor units (5) located over an area to be monitored; an interrogator unit (30) comprising a transmitter (402) for transmitting optical signals and receiver for obtaining data on the reservoir from the sensor units, a demodulator (418) for demodulating the received signals, and a recorder (420) for recording the demodulated signals. The arrangement includes an uplink optical cable (408) for transmitting the signals to the sensor array and a downlink optical cable (410) for transmitting signals from the array to the receiver. At least one of the optical cables has an optical amplifier (412, 414). The arrangement enables the interrogator to be remote from the array, for example 150km or more, obviating the need for significant power to be supplied at the array.

Description

technical field [0001] The present invention relates to sensor arrays, and more particularly to sensor arrays located in environments where sensor arrays are inaccessible. The invention is particularly suitable for subsea seismic sensor arrays, but it should be understood that the invention can be used with other types of sensors. Background technique [0002] Submarine seismic sensor arrays are widely used in the exploration and monitoring of oil and gas reservoirs beneath the ocean floor. In these seismic monitoring techniques, arrays of seismometers and / or hydrophones are deployed as sensor assemblies on the seafloor and used to detect reflected seismic waves, and the results are analyzed to provide insights into the geological structure beneath the seafloor. Information relating to the nature and state and to the presence of oil or gas within these structures. [0003] Seismic sensor arrays based on fiber optic sensors offer particular benefits for these applications. ...

AI Technical Summary

Problems solved by technology

Consequently, the system's interrogator will typically have significant complexity, such as that resulting in it occupying multiple electronics cabinets typically having a volume of 3 cubic meters, and will require a considerable power supply, such as one up to 12kW

This size and power requirement can cause problems, especially for smaller platforms where available space and power are limited, and in some cases, especially where arrays are located in deep water, localized platforms may not exist and require Perform all operations from the seabed

In this case, the repair and maintenance of interrogators showed considerable problems

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