The system was installed for Norsk Hydro in Oseberg Ost (East) well E-11C in the Norwegian sector of the North Sea.
Norsk Hydro ASA has for several years participated in research and development projects related to downhole instrumentation and "smart" well technology. The installation and testing of the dual fiber optic pressure and temperature gauge in E-11C is part of the technology collaboration with Otoplan/Weatherford.
Weatherford's fiber optics systems have been developed in response to operators' requirements for highly reliable monitoring systems over the life of the well. Fiber optics systems are inherently more reliable than the electronic equivalent as they have fewer parts, no moving parts and no downhole electronics. Coupled with enhanced surface acquisition performance, this results in improved system longevity. As well as improving reliability in monitoring the reserves over the life of the well, fiber optics enables a cost effective way of installing an array of sensors, including non-intrusive flow meters and in-well seismic sensors into the well on a single cable. Such an array of sensors provides better day-to-day production management and enables enhanced strategic management of the reservoir over the course of its life.
The DTS cable on well E-11C enables the customer to repeat the survey performed after installation to obtain temperature readings every meter. The pressure and temperature gauges give information about pressures and temperatures from the two producing zones in the reservoir. The downhole data is communicated to surface via one single 1/4" fiber optic cable.
The dual gauges are located and the DTS terminated just above the liner hanger, 235 meters below the 9 5/8" production packer, at a measured depth of 3773m and 73.2 degrees deviation. Initial well pressures were recorded at 289 bar and the producing temperature is approximately 125 degrees C.
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