Application of infrared thermal imaging technique in in-situ temperature field measurement of hydrate-bearing sediment under thermal stimulation

Natural gas hydrate is a green energy with great development prospects. The exploitation of natural gas hydrate has been attracting much attention. The temperature field distribution of hydrate-bearing sediment is a crucial indication on the heat or mass transfer characteristics and thermal properties of hydrate-bearing sediment during hydrate exploitation. However, to date, the acquisition means of temperatures of hydrate-bearing sediment have been limited to the discrete temperature measurement by using the contact-type temperature sensors inserted into hydrate sediment. The continuous evolution of temperature field of hydrate-bearing sediment can be hardly achieved. Thus, in this study, a new method applying the non-contact and non-destructive infrared thermal imager was developed and applied in the in-situ measurement of the continuous evolution of temperature field of hydrate-bearing sediment. The results confirm the feasibility of application of the infrared thermal imaging technique in the hydrate-related research. The complete continuous temperature fields of hydrate-bearing sediment and non-hydrate-bearing sediment under thermal stimulation were imaged and compared. The results indicate that the temperature field distribution of hydrate sediment is predominately controlled by the effective thermal conductivity of hydrate-bearing sediment. In addition, the effects of the type of hydrate-bearing sediment, heating power and particle size of sediment were investigated.