Abstract: An arrangement for monitoring a submarine reservoir includes a number of sensor units located in an array on the seabed, and an interrogator unit for obtaining data on the reservoir from the sensor units. The interrogator unit includes a transmitter unit for sending optical signals to the sensor array and a receiver unit for receiving modulated optical signals from the array. Optical radiation from an optical source is transmitted along an uplink optical fiber which is split in a number of positions to form the array. The receiver unit includes optical-to-electrical converters for converting the optical signals to electrical signals, a phase demodulator, a multiplexer, a signal processor, and recording unit. The interrogator unit is divided into a concentrator and an interrogator hub, where signals are transmitted between the interrogator hub and concentrator along a riser cable. This enables the interrogator to be moved between a platform and the seabed.

Abstract: An arrangement for monitoring a submarine reservoir comprises a number of sensor units located in an array (1) on the seabed, and an interrogator unit for obtaining data on the reservoir from the sensor units. The interrogator unit comprises a transmitter unit (20) for sending optical signals to the sensor array and a receiver unit for receiving modulated optical signals from the array. Optical radiation from an optical source (22) is transmitted along an uplink optical fibre which is split in a number of positions 36, 38 to form the array. The receiver unit comprises optical-to-electrical converters (54) for converting the optical signals to electrical signals, a phase demodulator (58), a multiplexer (60) for multiplexing signals from the phase demodulator, a signal processor (68) and recording unit (70).