A novel down-hole fiber optic sensor based on Fabry-Perot cavity and fiber Bragg gratings

With the rapid development of fiber optic sensing technology, more and more related monitoring programs begin to play an important role in oil and gas exploration. In the past, down-hole monitoring of temperature and pressure was dependent on pump partner, electronic pressure gauge and the capillary pressure gauge. However, such devices show many disadvantages in stability, reliability, accuracy and so on. In the interest of special anti-corrosion, seals, high temperature, high pressure treatment, and long life, the fiber optic sensor is critically investigated and a new design approach of fiber temperature and pressure sensor based on Fiber Bragg Gratings and Fabry-Perot Cavity is presented, respectively. The temperature and pressure resolution of this sensor can be as high as 0.3 degrees C and 3psi. Meanwhile, the sensor can work under the condition from 0 to 15000psi and from -25 to 300 degrees C. This paper describes the technical principles, characteristics and field application of the sensor in detail.