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Exciting fiber-optic test in Oseberg Øst well

August 28, 2002, 01:00 CEST

Hydro has used a fiber-optic pressure/temperature gauge in an oil reservoir for the first time. The down-hole measuring equipment was installed in remote-controlled well E-11C on the Oseberg Øst field, which started producing oil from the Ness and Etive formations on August 10.

The pressure gauges, which have so far functioned trouble-free, mark a new milestone in the development of smart offshore technology.

Conventional electric pressure gauge systems have performed unreliably in extreme conditions. Well E-11C has exceptionally tough conditions - the gauges must operate at a depth of 3,773 meters under 289 bar pressure. Where pressure is measured in the reservoir area, the temperature rises to a very high 125 degrees Celsius.

Pressure and temperature are measured in two places in the well so data from two zones can be monitored..

In fact, fiber-optics make it possible to measure temperature all the down the cable to the reservoir.

Pressure control and water injection

"Extensive knowledge of pressure conditions is imperative to well control," says Øyvind Midttveit, who is discipline manager for production technology on the Oseberg Øst field in Hydro Oil & Energy's Operations and Production Norway unit.

The well has functioned as a producer since starting operation, but will be converted to a water injector.

"Efficient operations are dependent on having precise knowledge about pressure conditions in the reservoir to optimally control water injection," he says.

Well E-11C has been drilled and completed with zone-controlled water injection to hold pressure up in the reservoir. The well produces oil from the two formations Ness and Etive . The fiber-optic sensors are supplied by Optoplan/Weatherford.

Pioneer project

"Fiber-optic costs more at the onset than other pressure and temperature measuring technology, but is expected to give more reliable information on high temperature. That's why we've provided research and development support to this project. After accruing some experience with the first well, we might well install the same technology in other wells.

Increased fiber-optic use is part of Hydro's strategy for better well instrumentation. R&D support helps maintain the tempo of technology development," comments Sigurd Erlandsen, at Hydro's research center in Porsgrunn.