Research On Fiber Bragg Grating Vibration Sensing Technology

With the development and progress of society,oil,natural gas,coal and other resources are constantly exploited by people,and conventional oil and gas reservoirs are becoming less and less.In order to solve this problem,the search and development of unconventional oil and gas reservoirs has become the main solution.Because unconventional oil and gas reservoirs have different distribution rules from conventional oil and gas reservoirs,exploration instruments for conventional oil and gas reservoirs are no longer applicable,and it is necessary to improve or develop new exploration instruments.Fiber grating vibration sensor has some advantages,such as: strong electromagnetic interference resistance,strong corrosion resistance,small size,light weight,high sensitivity.For this reason,this paper mainly studies the vibration sensor of fiber grating.This paper mainly studies the development trend of traditional vibration sensing technology,the basic principle of fiber Bragg grating and the application principle of fiber Bragg grating in vibration sensing technology,summarizes the advantages of fiber Bragg grating in the field of exploration,and briefly summarizes its development status.The main work of the paper is as follows:1.Firstly,the basic characteristics of the fiber Bragg grating vibration acceleration sensor with a cantilever beam structure were studied from the aspects of simulation and experiment.In order to improve the sensitivity of vibration acceleration sensor,the grating completely paste on the cantilever beam's way to hung up in the form of two paste way,and has carried on the experimental research,finally the experimental results show that the suspended paste the natural frequency of the vibration of the fiber Bragg grating sensor for the 90 Hz,flat area is 10 to 50 Hz,the sensitivity of 121 pm/g,which is 3.67 times higher than the sensor sensitivity that the grating is fully attached to the cantilever beam.2.A kind of fiber grating vibration sensor with sliding rod is proposed.Under the action of sliding rod,fiber grating is subjected to horizontal and vertical forces,and they are studied experimentally.The experimental results show that the natural frequency of the sliding rod type vibration sensor is 62 Hz,the flat area is 10-40 Hz,and the sensor sensitivity is 52.8 pm/g;The sensor sensitivity that only forces along the optical fiber axis is 30.9 pm/g;In contrast,the fiber grating can actually increase the sensitivity of the sensor by the force in both directions.3.Finally,the fatigue life,equivalent alternating stress and fatigue safety coefficient of cantilever beam are studied.In order to prolong the fatigue life of the cantilever beam,the size of the cantilever beam was optimized.