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Fiber Bragg Grating Sensors for the Oil Industry

View Article: PubMed Central - PubMed

ABSTRACT

With the oil and gas industry growing rapidly, increasing the yield and profit require advances in technology for cost-effective production in key areas of reservoir exploration and in oil-well production-management. In this paper we review our group’s research into fiber Bragg gratings (FBGs) and their applications in the oil industry, especially in the well-logging field. FBG sensors used for seismic exploration in the oil and gas industry need to be capable of measuring multiple physical parameters such as temperature, pressure, and acoustic waves in a hostile environment. This application requires that the FBG sensors display high sensitivity over the broad vibration frequency range of 5 Hz to 2.5 kHz, which contains the important geological information. We report the incorporation of mechanical transducers in the FBG sensors to enable enhance the sensors’ amplitude and frequency response. Whenever the FBG sensors are working within a well, they must withstand high temperatures and high pressures, up to 175 °C and 40 Mpa or more. We use femtosecond laser side-illumination to ensure that the FBGs themselves have the high temperature resistance up to 1100 °C. Using FBG sensors combined with suitable metal transducers, we have experimentally realized high- temperature and pressure measurements up to 400 °C and 100 Mpa. We introduce a novel technology of ultrasonic imaging of seismic physical models using FBG sensors, which is superior to conventional seismic exploration methods. Compared with piezoelectric transducers, FBG ultrasonic sensors demonstrate superior sensitivity, more compact structure, improved spatial resolution, high stability and immunity to electromagnetic interference (EMI). In the last section, we present a case study of a well-logging field to demonstrate the utility of FBG sensors in the oil and gas industry.

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Related in: MedlinePlus

(a) Schematic diagram of TCF-FBG directional accelerometer; (b) Image of TCF-FBG, insets show the zoomed images of gratings in fiber cladding (up) and fiber core (bottom); (c) The transmission spectrum of TCF-FBG with two well-defined resonances; (d) Real-time power output of cladding mode and core mode (blue curve) under the same vibration condition; (e) Angular dependence of acceleration responsivity of sensor.
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sensors-17-00429-f005: (a) Schematic diagram of TCF-FBG directional accelerometer; (b) Image of TCF-FBG, insets show the zoomed images of gratings in fiber cladding (up) and fiber core (bottom); (c) The transmission spectrum of TCF-FBG with two well-defined resonances; (d) Real-time power output of cladding mode and core mode (blue curve) under the same vibration condition; (e) Angular dependence of acceleration responsivity of sensor.

Mentions: In order to avoid the uncertainties associated with the reproducibility and spectral quality of tilted gratings, our group has developed a new vectorial vibration sensing mechanism. The sensor is created by writing a conventional FBG in the cladding of a short piece of thin-core fiber (TCF) spliced to standard single-mode fiber (SMF), as shown in Figure 5. The key to the success of this device lies in the inherent mismatch between the cores of the two fibers (which allows the coupling of core modes into cladding modes) and the precisely localized grating inscription within the fiber cladding (thanks to highly focused femtosecond laser inscription and photo-sensitivity of the TCF cladding). We show below that this device has superior spectral qualities that facilitate sensor interrogation and are significantly simple to fabricate. The grating inscription region is close to the core–cladding interface of the TCF, with the most of the grating within the fiber cladding and partially extending into the fiber core. With this configuration, two well-defined resonances in reflection have been achieved, which originate from the gratings in the core and the cladding, respectively, as shown by the “FBG core” and “FBG cladding” marked in Figure 5a.


Fiber Bragg Grating Sensors for the Oil Industry
(a) Schematic diagram of TCF-FBG directional accelerometer; (b) Image of TCF-FBG, insets show the zoomed images of gratings in fiber cladding (up) and fiber core (bottom); (c) The transmission spectrum of TCF-FBG with two well-defined resonances; (d) Real-time power output of cladding mode and core mode (blue curve) under the same vibration condition; (e) Angular dependence of acceleration responsivity of sensor.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5375715&req=5

sensors-17-00429-f005: (a) Schematic diagram of TCF-FBG directional accelerometer; (b) Image of TCF-FBG, insets show the zoomed images of gratings in fiber cladding (up) and fiber core (bottom); (c) The transmission spectrum of TCF-FBG with two well-defined resonances; (d) Real-time power output of cladding mode and core mode (blue curve) under the same vibration condition; (e) Angular dependence of acceleration responsivity of sensor.
Mentions: In order to avoid the uncertainties associated with the reproducibility and spectral quality of tilted gratings, our group has developed a new vectorial vibration sensing mechanism. The sensor is created by writing a conventional FBG in the cladding of a short piece of thin-core fiber (TCF) spliced to standard single-mode fiber (SMF), as shown in Figure 5. The key to the success of this device lies in the inherent mismatch between the cores of the two fibers (which allows the coupling of core modes into cladding modes) and the precisely localized grating inscription within the fiber cladding (thanks to highly focused femtosecond laser inscription and photo-sensitivity of the TCF cladding). We show below that this device has superior spectral qualities that facilitate sensor interrogation and are significantly simple to fabricate. The grating inscription region is close to the core–cladding interface of the TCF, with the most of the grating within the fiber cladding and partially extending into the fiber core. With this configuration, two well-defined resonances in reflection have been achieved, which originate from the gratings in the core and the cladding, respectively, as shown by the “FBG core” and “FBG cladding” marked in Figure 5a.

View Article: PubMed Central - PubMed

ABSTRACT

With the oil and gas industry growing rapidly, increasing the yield and profit require advances in technology for cost-effective production in key areas of reservoir exploration and in oil-well production-management. In this paper we review our group’s research into fiber Bragg gratings (FBGs) and their applications in the oil industry, especially in the well-logging field. FBG sensors used for seismic exploration in the oil and gas industry need to be capable of measuring multiple physical parameters such as temperature, pressure, and acoustic waves in a hostile environment. This application requires that the FBG sensors display high sensitivity over the broad vibration frequency range of 5 Hz to 2.5 kHz, which contains the important geological information. We report the incorporation of mechanical transducers in the FBG sensors to enable enhance the sensors’ amplitude and frequency response. Whenever the FBG sensors are working within a well, they must withstand high temperatures and high pressures, up to 175 °C and 40 Mpa or more. We use femtosecond laser side-illumination to ensure that the FBGs themselves have the high temperature resistance up to 1100 °C. Using FBG sensors combined with suitable metal transducers, we have experimentally realized high- temperature and pressure measurements up to 400 °C and 100 Mpa. We introduce a novel technology of ultrasonic imaging of seismic physical models using FBG sensors, which is superior to conventional seismic exploration methods. Compared with piezoelectric transducers, FBG ultrasonic sensors demonstrate superior sensitivity, more compact structure, improved spatial resolution, high stability and immunity to electromagnetic interference (EMI). In the last section, we present a case study of a well-logging field to demonstrate the utility of FBG sensors in the oil and gas industry.

No MeSH data available.


Related in: MedlinePlus