Oil extraction is now made from oil fields more difficult to reach. For improved performance and security more sophisticated tools have been developed equipped with sensors. They have to be adapted to very harsh environment such as pressure up to 2000 bars, temperature up to 300°C and aggressive fluids.
Fiber optics is increasingly used as intrinsic sensors, monitoring and communication technology. Fiber spectroscopy for instance is very useful to analyze products with carbon content.
Another important application is pipelines surveillance and monitoring. Pipeline leakage is a major problem for oil companies for economic and environment reasons. Fiber optic sensors are used to detect and locate such leakages. Either distributed or local sensor can give information about stress, temperature, vibration, sound, etc.
EXtrem environment… Oil field conditions are particularly difficult and very diverse such as deep sea exploration and sea platform, pit cementation, deep drilling. Resistance to abrasion, small bending radius, crushing, traction, etc. can be required. Special protections of optical fibers are necessary with technical cables or metallic tubing.
When optical fibers are used in harsh environment such as oil & gas applications, combining high temperature, high pressure and hydrogen rich environment, hydrogen then diffuses into the core of standard fibers increasing attenuation to a point where they are no longer usable. To solve this problem it is necessary to use carbon coated fibers the carbon layer being an effective barrier to hydrogen. Such fibers are generally also polyimide coated for temperature resistance
When high pressure is combined with high temperature it is no longer possible to use standard fibers (see below Hydrogen) or standard telecom components. SEDI-ATI has developed specific components such as feedthroughs, multimode couplers, connectors which can be associated with high performance fibers such as metal and carbon coated fibers or even sapphire fibers.
Fluorescence spectroscopy is very useful tot analyzes the composition of a sample for environment surveillance.
It involves the use of a light beam (normally laser in the ultraviolet) to excite the electrons of certain compounds’ molecules, forcing them to emit lower-energy light, generally in the visible range. A dichroïc filter can be used separate the excitation wavelength from the fluorescence. Optical fibers allow remote sensing, better resolution and miniaturisation.