Stingray tests permanent reservoir monitoring system

Offshore staff

GUILDFORD, UK -- Stingray Geophysical has delivered results from its analysis of data recorded during the final sea trial in the program to commercialize its Fosar permanent reservoir monitoring (seismic PRM) system. The results demonstrated excellent geophysical response characteristics and confirmed efficient installation, the company says.

The offshore test was performed in November 2008. An array of multi-component receivers, deployed in more than 260 m (853 ft) water depth, was trenched into the seabed for optimum geophysical coupling and protection from mechanical damage. A fiber-optic riser cable joined the seabed array to an opto-electronic interrogation unit situated on surface facilities. No subsea electrical power is required for the array.

A vessel, equipped with an airgun seismic source, acquired a 3D grid of shotpoints over the array and the resulting data from the seabed receivers were recorded by the compact interrogation unit. Analysis of these data confirmed the geophysical performance characteristics of the system, including its low noise floor, high vector fidelity, and capability to record seismic signals over an 180dB dynamic range. This range is 1,000 times greater than typical electrical systems, proving that the Fosar system can handle even the largest airgun arrays at close proximity to the sensor, the company says.

The Fosar system consists of four-component, passive fiber-optic sensors comprising one hydrophone and three orthogonally-mounted accelerometers per station or Optical Sensing Unit (OSU). The system benefits from an optical multiplexing architecture developed by Stingray to minimize the number of optical fibers required for a high channel-count array.

By successfully demonstrating the Fosar system deployment, operation, and acquisition of seismic data against reference electrical sensors, the company has achieved all of the objectives of its technology development program, including the delivery of high-fidelity sensor performance. The system is now commercially available for seismic permanent reservoir monitoring applications.

06/08/2009