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Fiber Bragg Grating Sensors for the Oil Industry

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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.


Simulation results: (a) FBG length versus response sensitivity; (b) Detection direction versus response sensitivity.
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sensors-17-00429-f013: Simulation results: (a) FBG length versus response sensitivity; (b) Detection direction versus response sensitivity.

Mentions: The wavelength shift sensitivity Sλ for UW detection can be written as [182]:(8)Sλ(λS/L,εm)=ΔλUS(λS/L,εm)λB0εm=ΔλUS(v/fSL,εm)λB0εm,where ΔλUS is the shift of the grating, λS is the wavelength of the UW, L is the length of the FBG, εm is the displacement amplitude of the UW, λB0 is the unperturbed Bragg resonance wavelength, ν is the UW velocity in the fiber, and fS is the UW frequency. The equation clearly shows that the UW sensitivity of sensor is a function of the ratio λS/L, i.e., it is highly associated with the λS or fS. According to the theoretical analysis in [172,182], in particular, there are three main operating regions as follows: the first region corresponding to ν/fSL << 1, where Sλ approaches zero, so the grating response is practically insensitive to the UW. The second region, corresponding to ν/fSL ≈ 1, where Sλ increases with the ratio ν/fSL, the third region, corresponding to ν/fSL >> 1, where Sλ approaches a maximum value. The simulations in Figure 13 illustrates the discussion above, where the increasing length of the FBG decreases the response frequency band of the FBG. Besides, the detection orientation is another factor to influence the ultrasonic response of the FBG. As shown in Figure 13b, the FBG presents different sensitivities to the UW in different directions. Evidently, the sensor must be fixed in a suitable direction to get high SNR signal.


Fiber Bragg Grating Sensors for the Oil Industry
Simulation results: (a) FBG length versus response sensitivity; (b) Detection direction versus response sensitivity.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

sensors-17-00429-f013: Simulation results: (a) FBG length versus response sensitivity; (b) Detection direction versus response sensitivity.
Mentions: The wavelength shift sensitivity Sλ for UW detection can be written as [182]:(8)Sλ(λS/L,εm)=ΔλUS(λS/L,εm)λB0εm=ΔλUS(v/fSL,εm)λB0εm,where ΔλUS is the shift of the grating, λS is the wavelength of the UW, L is the length of the FBG, εm is the displacement amplitude of the UW, λB0 is the unperturbed Bragg resonance wavelength, ν is the UW velocity in the fiber, and fS is the UW frequency. The equation clearly shows that the UW sensitivity of sensor is a function of the ratio λS/L, i.e., it is highly associated with the λS or fS. According to the theoretical analysis in [172,182], in particular, there are three main operating regions as follows: the first region corresponding to ν/fSL << 1, where Sλ approaches zero, so the grating response is practically insensitive to the UW. The second region, corresponding to ν/fSL ≈ 1, where Sλ increases with the ratio ν/fSL, the third region, corresponding to ν/fSL >> 1, where Sλ approaches a maximum value. The simulations in Figure 13 illustrates the discussion above, where the increasing length of the FBG decreases the response frequency band of the FBG. Besides, the detection orientation is another factor to influence the ultrasonic response of the FBG. As shown in Figure 13b, the FBG presents different sensitivities to the UW in different directions. Evidently, the sensor must be fixed in a suitable direction to get high SNR signal.

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&rsquo;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&rsquo; amplitude and frequency response. Whenever the FBG sensors are working within a well, they must withstand high temperatures and high pressures, up to 175 &deg;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 &deg;C. Using FBG sensors combined with suitable metal transducers, we have experimentally realized high- temperature and pressure measurements up to 400 &deg;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.