Fiber optic strain measurements using distributed sensor system under static pressure conditions

Kogure, Tetsuya; Horiuchi, Yuki; Kiyama, Tamotsu; Nishizawa, Osamu; Xue, Ziqiu; Matsuoka, Toshifumi

doi:10.3124/segj.68.23

Cited by 8 publications

(8 citation statements)

References 15 publications

(5 reference statements)

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“…This was obtained from calibration using a tensile tester with a displacement gauge. A standard metal plate with an optical fiber bonded (by an epoxy adhesive) was stretched under a strain-controlled condition (Kogure et al, 2015). These conditions matched those of the strain measurements during the current core test.…”

Section: /2019wr024795mentioning

confidence: 96%

“…Water Resources Research guarantee tight bonding. The same installation has been deployed in prior experimental investigations, which showed that DFOSS has similar or better performance compared to conventional strain gauges (Kogure et al, 2015;Xue et al, 2018). Because the fiber was much smaller than a usual strain gauge, the contact problem was less significant.…”

Section: Rock Sample and Experimental Setupmentioning

confidence: 99%

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Deformation‐Based Monitoring of Water Migration in Rocks Using Distributed Fiber Optic Strain Sensing: A Laboratory Study

Zhang

Xue

2019

Water Resources Research

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Rock deformation induced by pore‐fluid pressure carries useful information about fluid flow owing to hydromechanical coupling. Thus, obtaining spatiotemporal changes in rock deformation could provide improved understanding of the fluid and pressure migration in aquifers or the role of fluid in the evolution of rainfall‐induced landslide. Here we deployed high‐resolution Rayleigh‐scattering‐type distributed fiber optic strain sensing (DFOSS) to measure rock deformation while injecting water into low‐permeability dry sandstone. X‐ray computed tomography imaging was simultaneously used to visualize the water migration. DFOSS measurements showed the rock developed a dilation deformation that grew during water saturating process. The movement of water wetting front can be revealed by the changes in the measured distributed strain. Strain changes were shaped by poroelastic changes due to the fluid pressure buildup and swelling by the water–clay reaction (i.e., adsorption). The latter mechanism caused increase in the strain when water first entered the dry pore spaces and the change in pore pressure was slight. The mechanism continued contributed to the overall deformation to peak magnitude of ~600 μϵ together with poroelastic mechanism. However, after the rock was fully saturated, further deformation during the flow test can be explained by the poroelastic mechanism alone. Our study suggests that the two factors can be employed as signatures for effectively monitoring fluid behavior in natural sediments using DFOSS. Moreover, we obtained the spatial hydromechanical properties, permeability and stiffness, from the distributed strain measurement and pressure responses. Using DFOSS in the field may substantially improve our ability to monitor and model fluid activity related to rock deformations in reservoirs and rainfall‐induced landslides that would help in warning people of risks and preventing disasters.

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Section: /2019wr024795mentioning

confidence: 96%

Section: Rock Sample and Experimental Setupmentioning

confidence: 99%

Deformation‐Based Monitoring of Water Migration in Rocks Using Distributed Fiber Optic Strain Sensing: A Laboratory Study

Zhang

Xue

2019

Water Resources Research

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“…In order to make accurate predictions, a geomechanical model needs to be first calibrated against geophysical and geomechanical data obtained from monitoring. As a new technology, continuous and distributed fiber optic sensing (DFOS) technology based on Brillouin and/or Rayleigh scattering has great potential in geotechnical monitoring at both laboratory and field scales [16][17][18][19][20]. Optical fiber sensors have advantages such as their immunity against electromagnetic interference, low weight, small size, high sensitivity, and large bandwidth.…”

Section: Introductionmentioning

confidence: 99%

Fiber Optic Sensing for Geomechanical Monitoring: (2)- Distributed Strain Measurements at a Pumping Test and Geomechanical Modeling of Deformation of Reservoir Rocks

2019

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In this study distributed fiber optic sensing has been used to measure strain along a vertical well of a depth of 300 m during a pumping test. The observed strain data has been used in geomechanical simulation, in which a combined analytical and numerical approach was applied in providing scaled-up formation properties. The outcomes of the field test have demonstrated the practical use of distributed fiber optic strain sensing for monitoring reservoir formation responses at different regions of sandstone–mudstone alternations along a continuous trajectory. It also demonstrated that sensitive and scaled rock properties, including the equivalent permeability and pore compressibility, can be well constrained by the combined use of water head and distributed strain data. In comparison with the conventional methods, fiber optic strain monitoring enables a lower number of short-term tests to be designed to calibrate the parameters used to model the rock properties. The obtained parameters can be directly used in long-term geomechanical simulation of deformation of reservoir rocks due to fluid injection or production at the CO2 storage and oil and gas fields.

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“…It is noted that Rayleigh-based sensing has a much higher resolution than Brillouin-based sensing does. Rayleigh and Brillouin backscattering techniques have been successfully applied in measuring metallic plate strains [14]. In this study, they are applied to measure frequency shift along the interval of a single optical fiber which is attached to and circles around the peripheral of two different sandstone cylindrical core samples under controlled confining/pore pressure conditions in the laboratory.…”

Section: Introductionmentioning

confidence: 99%

Fiber Optic Sensing for Geomechanical Monitoring: (1)-Distributed Strain Measurements of Two Sandstones under Hydrostatic Confining and Pore Pressure Conditions

Xue

Shi

Yamauchi³

et al. 2018

Applied Sciences

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In this study distributed optic fiber has been used to measure both the Rayleigh and Brillouin frequency shift of two different sandstone core samples under controlled hydrostatic confining and pore pressure in the laboratory. The Berea sandstone core is relatively homogeneous, whereas the Tako sandstone core is visibly heterogeneous with a coarse-grain and a fine-grain region. Rayleigh frequency has been found to have a superior performance over Brillouin frequency in terms of better consistency (less scattering) in the tests carried out. The strain gauge readings reveal considerable anisotropy in the stiffness of the Berea core between perpendicular (vertical) and parallel to the bedding (hoop) directions. The strains converted from Rayleigh frequency shift measurements agree reasonably well with readings by one of the four hoop strain gauge channels under increasing confining/pore pressure. For the Tako sandstone core, the contrast in the grain-size, and thus rock elastic properties, is clearly reflected in the hoop strain measurement by both strain gauges and distributed optic fiber. The outcomes of the test have demonstrated successfully the use of a single optic fiber for measuring rock strain response at different regions of a heterogeneous core sample along a continuous trajectory.

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Fiber optic strain measurements using distributed sensor system under static pressure conditions

Abstract: 2014 9 26 * ( ( ) CO2 ) 690-8504 1060 ** 615-8540 C1 *3 ( ) CO2 619-0292 9-2

Cited by 8 publications

References 15 publications

Deformation‐Based Monitoring of Water Migration in Rocks Using Distributed Fiber Optic Strain Sensing: A Laboratory Study

Deformation‐Based Monitoring of Water Migration in Rocks Using Distributed Fiber Optic Strain Sensing: A Laboratory Study

Fiber Optic Sensing for Geomechanical Monitoring: (2)- Distributed Strain Measurements at a Pumping Test and Geomechanical Modeling of Deformation of Reservoir Rocks

Fiber Optic Sensing for Geomechanical Monitoring: (1)-Distributed Strain Measurements of Two Sandstones under Hydrostatic Confining and Pore Pressure Conditions

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