Research on design and preparation technology of optical fiber for high temperature oil and gas wells

Optical fiber sensing technology has been widely used in oil and gas Wells because of its unique advantages. The down-hole is a hot and corrosion environment, which requires high temperature resistance and hydrogen damage resistance of sensing fiber. In response to the requirements of this application, this paper introduces a special optical fiber with a core designed to resist hydrogen loss, and using carbon sealing coating and optimized high-temperature resistant polyimide (PI) coating. Through a series of optimization measures for optical fibers, the prepared fibers have better temperature resistance and hydrogen loss resistance. The results of the strength test combined with Weibull analysis show that the strength of the fiber has been improved, and the consistency of the fiber has also been greatly improved. Through attenuation performance testing of optical fibers in high-temperature environments, the optimized fiber has better temperature resistance compared to conventional fibers, and the temperature induced attenuation is less than 0.11dB/km. The results of hydrogen loading tests show that hydrogen induced attenuation is significantly reduced compared to conventional optical fibers. The special core design and carbon coated film are effective, which is exactly what the distributed temperature sensing (DTS) for oil and gas wells expects.