Fiber optics to map oil fields

17 Jun 2002

A UK and a US company team up to develop seismic sensors based on fiber-optic interferometry.

The oil and gas industry is set to benefit from a project that will develop fiber-optic sensors to image oil reservoirs.

UK-based QinetiQ and Input/Output Inc, US, have agreed a strategic alliance that should see prototype systems within two years, and the first full-size systems by 2006.

They claim that the seismic sensor arrays under development will give better images of oil and gas reservoirs, increasing the amount of fuel that can be extracted.

QinetiQ fiber-optic group manager Michael Gill said: "Fiber-optic sensors represent the next generation of technology in this field."

Although fiber-optic sensors are currently used in the oil and gas industry to measure slowly-varying quantities such as pressure and temperature, the seismic signals will demand high-sensitivity, dynamic sensing. No such high-sensitivity sensors are currently operational.

QinetiQ and Input/Output plan to deploy arrays of over 250 sensors on a single fiber. These will measure vibrations transmitted through the ground using interferometry, with the signals built up to form an image of the oil reservoir.

The sensors will be driven using arrays of lasers operating at closely-spaced wavelengths, with seismic data extracted by both time and wavelength multiplexing.

Two types of system are being investigated: seabed arrays, which must operate at the high pressures of the ocean floor; and downwell sensors, which need to withstand both high pressure and high temperatures (over 150 ° C). The downwell sensors will require specialist components, including specially coated optical fibers, which are currently under development.

Author
Michael Hatcher is technology editor of Opto & Laser Europe magazine.