Heat conduction and thermal convection on thermal front movement during natural gas hydrate thermal stimulation exploitation

Abstract

Natural Gas Hydrate (NGH) has attracted increasing attention for its great potential as clean energy in the future. The main heat transfer mode that controls the thermal front movement in the process of NGH exploitation by heat injection was discussed through NGH thermal stimulation experiments, and whether it is reliable that most analytical models only consider the heat conduction but neglect the effect of thermal convection was determined by the comparison results between experiments and Selim's thermal model. And the following findings were obtained. First, the movement rate of thermal front increases with the rise of hot water injection rate but changes little with the rise of the temperature of the injected hot water, which indicated that thermal convection is the key factor promoting the movement of thermal front. Second, the thermal front movement rates measured in the experiments are about 10 times that by the Selim's thermal model, the reason for which is that the Selim's thermal model only takes the heat conduction into account. And third, theoretical calculation shows that heat flux transferred by thermal convection is 15.56 times that by heat conduction. It is concluded that thermal convection is the main heat transfer mode that controls the thermal front movement in the process of NGH thermal stimulation, and its influence should never be neglected in those analytical models.

The semi-analytical two-phase productivity model of natural gas hydrate by depressurization

“…天然气水合物(Natural Gas Hydrate, NGH)因其分 布广、资源量大、洁净等特点成为最具潜力的可替代 新能源 [1][2][3][4] , 美国、日本、俄罗斯等国家都将NGH列 入国家重点发展战略并进行了试采 [5][6][7][8] . 2017年5月18 日, 我国南海神狐海域NGH试采成功, 采用降压法连 续生产60天, 取得了重大进展 [9,10] .…”

Geothermal heat use to eliminate hydrate formations in oil deposit injection wells

“…The study of hydrate formation problem in the technological lines of downhole wells and bottomhole zone is of the highest relevance. The search for strategies and methods of eliminating excess hydrate formation, for different regime and technological conditions of oil field development, increases in depletion conditions of explored oil reserves in the world [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. This is due, in particular, to the increasing need for flooding and injection of various gases compositions into depleted deposits to intensify oil production.…”

“…The problem of regulating the flow temperature in a porous hydrocarbon-saturated medium to reduce the growth of gas hydrate zone 3 (Fig. 2) on the one hand, and maximize the mass flow rate through the injection circuit on the other is known [9]. It is solved using heaters and heat exchangers.…”

“…In [10], it was shown that a small change in the percentage of impurities leads to a significant change in the temperature of hydration. In [9][10][11] it is emphasized that important factors of hydrate formation in addition to the composition of natural gas are under pressure and temperature conditions and capillary phenomena.…”

Investigation of hydrate slurry flow behaviors in deep-sea pipes with different inclination angles

“…In the 1980s, Vysniauskas and Bishnoi began to research on hydrate kinetics, which opened a new chapter in the safety of hydrate flow from "preventing" to "controlling" [7]. Nowadays, hydrate slurry flow research has a rich content, and many scholars from various countries have carried out many loop experiments and numerical simulation studies [8][9][10].…”