Experimental investigation on gas hydrate recovery using temperature separation mechanism of vortex tube

Abstract

As a type of clean energy, natural gas hydrate production is currently receiving great attention. The main disadvantage of conventional thermal stimulation method is great heat loss during delivering of hot fluid. A novel hydrate recovery technique using the vortex tube temperature separation effect is proposed in this paper. The compressed gas is tangentially injected into the vortex tube to generate hot stream to decompose solid hydrate in site. Experiments were carried out in a large-scale lab reactor (100 L) and the decomposition behavior of both sandy and sand free deposits are investigated. Experimental results show that the temperature near the hot end of vortex tube increase and the resistivity decrease gradually due to hydrate dissolve under the effect of hot tube of the vortex tube. For the sandy reservoir, the production time is 407 min and 415 L gas is recovered. As to the sand free reservoir, the recovery time is 2220 min and 238 L gas is obtained. The self-preservation behavior is observed during the decomposition process of sandy deposit. Compared with conventional heating injection techniques, the present method has the merits of no chemical injection, no moving parts, low heat loss and little maintenance.