Potential applications of distributed optical fiber sensor in hydrate‐induced sedimentary deformation research

Natural gas hydrate is regarded as a potential clean energy source. However, hydrate phase transition during gas production leads to significant hydrate‐bearing sedimentary layer deformation, which is one of the main obstacles for safe hydrate exploitation. In this study, distributed optical fiber sensors were used to examine the porous medium deformation induced by phase change and verify its feasibility for application in hydrate research. Experiments on ice formation in a porous medium were conducted to mimic the hydrate formation in sediments. Optical fiber sensors were used to record and analyze the strain characteristics caused by the deformation of porous medium during the phase change process. The frequency shift during the cooling process shows that the fiber segment sensitivity is influenced by its initial length and tightness. In experiments with porous medium, the strain caused by the phase change exhibited a linear trend. In a comparative experiment using pure water, the strain caused by the phase change showed a nonlinear trend. The results indicate that the porous medium deformation induced by phase change can be accurately evaluated using strain data from distributed optical fiber sensors. The strain results also reflect the rate of the phase change. This study proves that the distributed optical fiber sensor has the potential to clarify the deformation characteristics of porous medium caused by hydrate phase change.