A Research And Design Of Fiber Bragg Grating Temperature Sensor Mounted In Drill Pipe

The series of advantages of fiber optic technology made it quickly swept the world and became the global information neural and industrial foundation.Fiber Bragg Grating technology is a fiber grating sensing technology developed on the basis of optical fiber communication.Compared with the tremendous success of optical fiber communication technology,the fiber grating sensor is in the ascendant.Since the first use of fiber Bragg grating sensing in 1989,the advantages of fiber grating sensor probes,small electromagnetic interference,chemical corrosion resistance,easy coupling with fiber,and high sensitivity,have attracted wide attention from experts and scholars around the world.Up to now,FBG sensors have been widely used in the fields of civil construction quality inspection,aircraft fuel storage box monitoring,space shuttle monitoring,medical image detection,mine oil well temperature detection,etc.,and already have some achievements.FBG sensors still have broad application prospects and development potential.This paper mainly studies the application of fiber Bragg grating sensors in measurement while drilling.It aims to realize real-time collection of wellbore temperature near the drill bit during drilling during oil drilling.In order to facilitate drilling well logging,such as wellbore pressure and other real-time logging parameters,it can effectively warn well drilling accidents such as blowouts and lost circulation,and improve the safety of oil drilling operations.At present,the fiber grating sensors existing on the market are mostly separated states of broadband light source,sensor and demodulation system,and the demodulation device tends to be large in size,which is difficult to meet the field requirements of measurement while drilling.In view of these shortcomings of the existing fiber Bragg grating sensors,the broadband light source,temperature sensing and wavelength demodulation circuits of the fiber Bragg grating temperature sensor are integrated and miniaturized.Based on the relevant research results,the simulation principle circuit and width are designed.Printed circuit boards that are less than 4 cm in length and can be embedded in drill pipe shorts are basically compliant with the measurement while drilling.The test results show that the working temperature of the system is equivalent to working at a depth of 1694 meters downhole,and the measurement accuracy can reach 1 °C,which can meet the requirements of the design of the system.In order to meet these requirements,this paper uses a self-made broadband source and wavelength demodulation system.The innovation of this paper is to realize the integration of broadband light source,temperature sensing and temperature demodulation.From this perspective,this paper introduces the working principle of fiber Bragg grating temperature sensor in detail,the realization principle and implementation of erbium-doped fiber broadband source and the work of tunable FP filter.Principle and demodulation temperature scheme design.In addition,the paper also compares the advantages and disadvantages of the common different fiber Bragg grating reflection wave wavelength demodulation methods.In the implementation of erbium-doped fiber broadband source,the temperature closed-loop control of the 980 nm pump laser is the focus,because the stability of the temperature has a great impact on the performance of the laser,which will affect the broadband source.The wavelength demodulation design of the tunable FP filter is the top priority of this paper.This paper introduces several parameters such as the free spectral range,the fineness and the piezoelectric ceramic driving voltage of the tunable FP filter.Understand the meaning of these parameters can better design the wavelength demodulation system to improve the accuracy of the system demodulation temperature.At the end of the paper,the tunable F-P filter driving characteristics experiment,the fiber Bragg grating temperature sensitivity experiment and the system temperature demodulation experiment are carried out.The results were in line with expectations and completed the full content of this article.