Gas Production from Methane-Hydrate-Bearing Sands by Ethylene Glycol Injection Using a Three-Dimensional Reactor

Abstract

The gas production from methane-hydrate-bearing sediment by injecting ethylene glycol (EG) solution was investigated using a three-dimensional experimental apparatus. Eight experimental runs were performed to examine the influence of operation conditions on hydrate dissociation by EG injection. The variations of pressure and temperature distribution in the reactor stimulated by the injected EG were obtained for the gas production process of the hydrate. The variation trend of temperature in the injection stage shows a shape of a “well” because of heat transfer and hydrate dissociation. The appearance sequence of temperature “well” and “well” depth is different for every port at different depths and radii. The effects of the concentration and quantity of EG and soaking time on the gas production ratio are examined. It shows that there exists an optimal value of the mass ratio of injected EG solution to initial water, where a maximum gas production ratio appears. When other conditions are similar, the gas amount produced by hydrate dissociation increases with the increase of the inhibitor concentration. The gas production efficiency increases with the decrease of the EG quantity and the increase of the EG concentration.

Review of natural gas hydrates as an energy resource: Prospects and challenges

“…These studies also reported the existence of an optimal 'production efficiency', defined as volumetric rate of gas recovered per unit mass of EG injected. This optimum amount of inhibitor was later found to be related to the pore volume below the well inlet [147]. It has also been reported that the presence of inhibitor lowers the heat of dissociation which improves heat efficiency by approximately 3.5 times according to the concentration of inhibitor [144].…”

“…Increasing EG concentration generally results in an increased gas production ratio [146,147]. These studies also reported the existence of an optimal 'production efficiency', defined as volumetric rate of gas recovered per unit mass of EG injected.…”

Investigation into optimization condition of thermal stimulation for hydrate dissociation in the sandy reservoir

“…To make the utilization of this resource economically viable, it is imperative to exploit the gas from the hydrate reservoir effectively and safely. The major potential methods for producing gas from hydrates are depressurization [11][12][13], thermal stimulation [14][15][16][17][18], inhibitor stimulation [19][20][21][22], and carbon dioxide replacement [23][24][25]. The depressurization is considered as the most economically feasible and the least energy intensive method.…”

Experimental Simulation of the Exploitation of Natural Gas Hydrate

“…It was found that the gas production rate tends to reduce significantly if the brine concentration is excessively high. Our group investigated the gas production from methane hydrate-bearing sands by ethylene glycol injection using a three-dimensional apparatus [107]. As shown in Figure 9, there exists an optimal value of mass ratio of injected ethylene glycol solution to initial water, where a maximum gas production ratio appears.…”

“…Figure 9. Variation of the gas production ratio with R EG-w (the ratio of injected ethylene glycol solution mass to the initial water mass) [107]. …”