Natural gas hydrate dissociation by hot brine injection

Abstract

Hot brine injection is one of the most effective dissociation methods of natural gas hydrate, and the movement of thermal front is a key parameter to evaluate the production performance by hot brine injection. Based on the principle of energy conservation, a mathematical model for thermal front movement of gas hydrate dissociation by hot brine injection is developed, which is derived through Laplace transform. In addition, an experimental study on the movement of thermal front is conducted with a self-designed 1D natural gas hydrate dissociation apparatus. The thermal front movement of the experiment is compared with that calculated from the mathematical model established in this paper as well as other two models proposed by Selim and Sloan (1990 Selim, M. S., and Sloan, E. D. (1990). Hydrate dissociation in sediment. SPE 16859. [Google Scholar]) and Tang et al. (2006 Tang, L., Li, G., Feng, Z., et al. (2006). Mathematical simulation of gas hydrate dissociation by heating injection. Nat. Gas Industry 26:105–107. [Google Scholar]), respectively. It turns out that what fits better with the experimental data is the energy conservation model, which includes the effect of heat used to warm the dissociated reservoir, heat absorption by hydrate dissociation and heat loss to the cap and base sediments. Therefore, this energy conservation model is an effective method to analyze the thermal front of gas hydrate dissociation by hot brine injection.