Optical fiber sensors have been tested used by the oil and gas exploration and production industry since the 1990s; however, it is only in recent years that their installation has been recognized as being of sufficient value to force incorporating them in the plans for monitoring entire fields. Of the intrinsic sensor types, single-point pressure and temperature gauges are most directly comparable with existing electrical gauges. Optical fiber gauges are consistent with usual practice, but their ability to operate at much higher temperatures and in very hostile environments makes them uniquely suitable in many oilfields and their share of gauge installations is growing.
Optical fibers are unique, however, in that they enable the use of fully distributed sensors, which measure the quantity of interest at every point of the well and continuously over time, albeit at a somewhat lower resolution of the measurand than that generally offered by point sensors. More than 1,000 wells have been monitored by distributed temperature sensors and the distributed measurement of vibration is rapidly gaining interest in the oilfield. High-temperature optics have also enabled a wide range of fluid characterization techniques to be ported to the hostile wellbore environment.
Research, technology development and commercialization of optical fiber sensors as well as their continuously growing technical application have become a story of success worldwide and in Germany as well. German fiber sensor research and industry achieved remarkable milestones in the 1980ies and 1990ies, such as first field tests of magneto-optic current sensors in power facilities or of micro-bending fiber strain sensors in a highway bridge. Recent progress and the state of the art of optical fiber sensing in Germany are demonstrated by examples of advanced fiber Bragg grating and distributed sensor system applications, fiber gyroscopes and other interferometric sensors, chemical and bio-medical sensors, and sensors based on polymer fibers as well.
Connected with the growing international cooperation, the potential of German research and industry will be discussed briefly in terms of novel fiber-optic sensor system concepts, of increasing maturity and reliability of this exciting sensor technology and of new applications and markets.
Fiber grating sensor technology has attracted substantial industrial interests in the last decade. They have increased in acceptance and widespread use for structural health sensing and condition monitoring applications in civil engineering, aerospace, marine, oil & gas, and railways. Most civil structures built by the Chinese Government in the past five years are instrumented with FBG sensing networks. FBG sensors are unique compared with other types of optical sensors and have proven to be durable and reliable, and offer tremendous benefits to the building, petrochemical and railway industries. As more FBG sensors are employed in these industries, more intimate information will be gained to realize the full potential of the FBG sensor technology to realize truly intelligent monitor systems for the various industries.