10:45 〜 11:00
[HSC05-07] Downhole Deformation Monitoring with High-Spatial-Resolution Distributed Strain Measurement in Optical Fiber during Water Injection Test
キーワード：Water injection test, Distributed Fiber Optic Strain Sensing DFOSS, Geomechanical deformation, Lithological heterogeneity, Pressure breakdown
Introduction:
The fluids are injected into the subsurface around the world for various purposes which may induce a ground surface deformation due to the subsurface pressure buildup, Without the continuous strain data from the deep deformation to the surface, it is not easy to correlate the subsurface pressure changes with surface deformation, the distributed fiber optic strain sensing DFOSS tool could provide accurate deformation measurements at relatively low cost and permanent monitoring technique, In this study (DFOSS) was used to measure strain profile during a water injection test, where we installed two different fiber cables behind the casing in the three wells with different distances from the injection well, aiming to confirm the strain sensitivity of the fiber cables to the fluid migration behaviors.
Data:
As a part of the R&D project commissioned to the Geological Carbon Dioxide Storage Technology Research Association by the New Energy and Industrial Technology Development Organization (NEDO) and the Ministry of Economy, Trade, and Industry (METI) of Japan. A pilot water injection test was conducted in Mobara site /Chiba prefecture on January 2020, the water injected in a new injection well with depth 247m and the strain monitoring in there monitoring well with depth 180, 300, and 240m and distance from the injection well 5.5, 5.7 and 16.6 respectively.
Method:
DFOSS was used to measure strain profile in three shallow wells during water injection tests which carried out on March 2020, two different fiber cables installed behind the casing in the three wells with different distances from the injection well. the combined strain profile, pressure, and lithological heterogeneity analysis were conducted.
Result and Discussion:
The results suggested the strain measurements by the two different cables were almost the same, and there was no big difference in geomechanical deformation among the wells despite the distance to the injection well. From the combined strain profile, pressure, and lithological heterogeneity analysis, the strain responses under, within, and upper the injection zone has been successfully interpreted and the delayed strain response appeared at 6 m upper the injection zone was resulted from the pressure breakdown. the distributed strain fiber successfully could detect the deformation at the mud-sand alternation in high spatial resolution.
The fluids are injected into the subsurface around the world for various purposes which may induce a ground surface deformation due to the subsurface pressure buildup, Without the continuous strain data from the deep deformation to the surface, it is not easy to correlate the subsurface pressure changes with surface deformation, the distributed fiber optic strain sensing DFOSS tool could provide accurate deformation measurements at relatively low cost and permanent monitoring technique, In this study (DFOSS) was used to measure strain profile during a water injection test, where we installed two different fiber cables behind the casing in the three wells with different distances from the injection well, aiming to confirm the strain sensitivity of the fiber cables to the fluid migration behaviors.
Data:
As a part of the R&D project commissioned to the Geological Carbon Dioxide Storage Technology Research Association by the New Energy and Industrial Technology Development Organization (NEDO) and the Ministry of Economy, Trade, and Industry (METI) of Japan. A pilot water injection test was conducted in Mobara site /Chiba prefecture on January 2020, the water injected in a new injection well with depth 247m and the strain monitoring in there monitoring well with depth 180, 300, and 240m and distance from the injection well 5.5, 5.7 and 16.6 respectively.
Method:
DFOSS was used to measure strain profile in three shallow wells during water injection tests which carried out on March 2020, two different fiber cables installed behind the casing in the three wells with different distances from the injection well. the combined strain profile, pressure, and lithological heterogeneity analysis were conducted.
Result and Discussion:
The results suggested the strain measurements by the two different cables were almost the same, and there was no big difference in geomechanical deformation among the wells despite the distance to the injection well. From the combined strain profile, pressure, and lithological heterogeneity analysis, the strain responses under, within, and upper the injection zone has been successfully interpreted and the delayed strain response appeared at 6 m upper the injection zone was resulted from the pressure breakdown. the distributed strain fiber successfully could detect the deformation at the mud-sand alternation in high spatial resolution.