Sputter Deposited Carbon Material based Fabry-Perot Sensor and Downhole Application

To prevent hydrogen-induced loss and achieve long-term effective parameters monitoring in harsh downhole environment, we proposed a Fabry-Perot sensor with vacuum sputter deposited carbon coating film, in which we employed a deposition technology with a higher particle kinetic energy, closer substrate adhesion, and denser films, to deposit the coating film on the surface of the quartz capillary glass tube to protect the sensor from corrosion. The sensitivity and accuracy of the Fabry-Perot sensor with carbon film deposition can reach 369 nm/MPa and 0.02% FS, respectively. Meanwhile, the sensor has less hysteresis error and good pressure linearity of more than 0.99999 for repeatable pressure measurement. The downhole practice monitoring data indicated that this fiber-optic sensor exhibited excellent performance and the sputter deposited carbon coating can effectively decrease hydrogen loss.