1. Kazan National Research Technical University named after A. N
Kazan National Research Technical University named after A.N. Tupolev – KAI (KNRTU-KAI)1 SPC “Sensorika”, Ltd., Russia, Skolkovo2
Combined Brillouin sensor system for simultaneous local and distributed temperature and strain measurements for downhole telemetry
Nureev I.I.1, Agliullin T.A.1*, Kadushkin V.V.1,
Kurbiev I.Y.2, Proskuriakov A.D.2
Krasnoyarsk 2019 1

2. Combined Brillouin sensor system for simultaneous local and distributed temperature and strain measurements for downhole telemetry
Probing scheme of TEFBS. The distance between the central frequency B and the laser frequency is chosen in a way to eliminate the intersection of the TEFBS spectrum and the frequency of pump laser along with its probing component
Optoelectronic scheme of combined sensor system for distributed Brillouin optical frequency analysis
(a) Intensity of the reflected pulse from TEFBS 1 and 2 after filtering; (b) after inclined filter 2

3. Optical spectra of TEFBS1 (6.15 GHz) and TEFBS2 (8.96 GHz)
Combined Brillouin sensor system for simultaneous local and distributed temperature
and strain measurements for downhole telemetry
Beating signal at the photodetector:
After frequency filtering:
Optical spectra of TEFBS1 (6.15 GHz) and TEFBS2 (8.96 GHz)
Spectra of TEFBS1,2 and the laser
Signal spectrum after the PD 3

4. Combined Brillouin sensor system for simultaneous local and distributed temperature
and strain measurements for downhole telemetry
(a)
(b)
Combined downhole pressure and temperature sensor based on a dual TEFBS: a) - generalized design; b) - appearance
Armoured fiber-optic sensing cable
Distributed thermogram along the borehole 4

5. Combined Brillouin sensor system for simultaneous local and distributed temperature
and strain measurements for downhole telemetry
Conclusion
A scheme utilizing Brillouin optical frequency distributed analysis with a quasi- distributed approach based on DEFBS is proposed, which makes it possible to simultaneously carry out distributed and local measurements of temperature. The proposed highly integrated circuit uses a conventional narrow-band optical source broadened in spectrum to a temperature measurement range and has a common receiving module on the same sensor fiber. For distributed measurements, a single- mode optical fiber is used, and for the local measurements, two DEFBS are used. The achieved resolution for calibrating the distributed system is 0.01 °C and is determined by DEFBS. The possibilities for measuring point pressure and distributed temperature are opened independently because of the work done. The results of numerical experiments show that both the distributed temperature and pressure can be measured with only minor hindrances. Additionally we use this system in collaboration for power transmission line monitoring. 5