Research and development of a dynamic temperature and stress monitoring probe for hydrate reservoirs based on fiber optic sensing technology

Studying the changes in temperature and stress of hydrate-bearing sediment (HBS) during hydrate growth, decomposition, and deformation is crucial for understanding the destabilization mechanism of hydrate reservoir. To monitor the changes of internal temperature and stress in HBS during these processes, we proposed a temperature and stress monitoring scheme for HBS based on fiber-optic sensing technology, for which an optical fiber monitoring probe was designed. The feasibility and precision of the probe in the temperature and stress of HBS were compared with those of conventional sensors. Additionally, the changes of horizontal stress of HBS during hydrate formation and dissociation were effectively monitored by the optical fiber sensor. Experimental results show that the stress and temperature obtained by fiber-optic probe exhibit similar trends to those obtained with conventional sensors. However, some differences were observed due mainly to the heterogeneity of the HBS and the distance between the loading point and the sensing point. Overall, the fiber optic probe could better capture the increase in compressive stress caused by hydrate formation and the decrease in horizontal stress of hydrate-bearing sediments during hydrate decomposition.