Multiple fiber-optic sensors run in North Sea well

Norsk Hydro ASA has installed downhole—for the first time in the world—multiple fiber-optic sensors combined with surface-controlled downhole flow-control components.

By OGJ editors

HOUSTON, Sept. 9 -- Norsk Hydro ASA has installed downhole—for the first time in the world—multiple fiber-optic sensors combined with surface-controlled downhole flow-control components, according to Weatherford International Ltd., supplier of the intelligent technology.

The sensors, in Well E-11C in Oseberg East field in the North Sea, include pressure and temperature gauges and a distributed temperature sensing line.

These downhole sensor arrays provide data for day-to-day production management and enable strategic reservoir management during the field's life.

Weatherford says the distributed temperature line in Well E-11C lets Norsk Hydro obtain temperature readings every meter, so that it can repeat downhole temperature surveys, and the pressure and temperature gauges provide data from the two producing zones in the reservoir.

A single 1/4-in. fiber-optic line carries the data to surface.

The dual gauges and the termination of the fiber-optic cable are set in the completion string at 3,773 m (12,380 ft) measured depth and at a 73.2° hole deviation, which is just above the liner hanger and 235-m below the 9 5/8-in. production packer.

The well had an initial downhole pressure of 4,290 psi and a producing temperature of about 125° C. (257° F.)

Weatherford claims that fiber optics has more reliability than the electronic equivalent because it has fewer parts, no moving parts, and no downhole electronics.

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