Reflective optical fiber sensing network for monitoring in well logging

This paper proposes a reflective fiber-optic sensor network for multiparameter state monitoring in oil and gas wells. The network is composed of a ground-based sensing signal demodulation system, a fault detection module, and an underground optical fiber sensing topology. In addition to demodulating sensor signals transmitted in reverse transmission from underground, the ground system utilizes reflected signals at specific wavelengths to achieve real-time fault monitoring of all optical fibers in wells and locate the fault points precisely. The underground system consists of optical fiber sensors and redundant sensing fibers, with the end face of each optical fiber coated with a highly reflective film with a specific wavelength. Afterward, optical fiber sensors are specially protected and deployed along the outer surface of the tubing inside the well, enabling long-term monitoring of parameters such as temperature and pressure. The effectiveness of the network was validated by integrating DTS and FBG sensors in a production well; experimental results demonstrated the network's feasibility and effectiveness in oil and gas well testing environments.