Experimental Investigation into the Production Behavior of Methane Hydrate in Porous Sediment with Hot Brine Stimulation

et al. 2013

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Abstract:To evaluate the gas production performance of the hydrate accumulations in the South China Sea, a numerical simulation with warm brine stimulation combined depressurization has been conducted. A dual horizontal well system is considered as the well configuration in this work. In order to reduce energy input and improve energy utilization, warm brine (<30 °C) instead of hot brine (>50 °C) is injected into the reservoir for hydrate dissociation. The effect of the intrinsic permeability of the hydrate reservoir, the salinity and the temperature of the injected brine to gas hydrate exploitation have been investigated. The numerical simulation results indicate that the average gas production rate Q avg is about 1.23 × 10 5 ST m 3 /day for the entire hydrate deposit, which has the same order of magnitude compared with the commercially viable production rate. The injected brine can be pumped out from the upper production well directly after the hydrate between the two wells is dissociated completely. Thus, the effective region of heat and inhibitor stimulation is limited. The sensitivity analyses indicate that the dissociation rate of hydrate can be enhanced by increasing the temperature of the injected brine and raising the salinity of the injected brine. The parametric study of permeability shows that the hydrate of the reservoir with the larger permeability has a higher dissociation rate. OPEN ACCESS

Section: Sensitivity To the Salinity Of The Injected Watersupporting

confidence: 89%

Section: Introductionmentioning

confidence: 97%

Evolution of Hydrate Dissociation by Warm Brine Stimulation Combined Depressurization in the South China Sea

et al. 2013

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“…The common methods for hydrate dissociation are: (1) the depressurization method, in which the hydrate reservoir pressure is reduced below the equilibrium decomposition pressure to decompose the hydrate [37,38]; (2) the thermal stimulation method, in which the hydrate reservoirs are heated above the equilibrium decomposition temperature to decompose the hydrate [21,39]; (3) the chemical injection method, in which chemicals (such as methanol or ethylene glycol) are injected into the reservoir to change the equilibrium hydrate decomposition conditions and induce hydrate dissociation [40,41]; and (4) the CO 2 replacement method, in which CO 2 is injected into the hydrate reservoirs to replace the methane gas [42,43]. A series of field production tests from the practical hydrate reservoirs have confirmed the availability of these methods, such as the test at the Mackenzie Delta (Northwest Territories, Canada) by thermal stimulation and depressurization methods [19], and the offshore test at the Nankai Trough, Japan by the depressurization method during 12-18 March 2013 [44].…”

Section: Methods Of Production and Well Designmentioning

confidence: 99%

Evaluation of Gas Production from Marine Hydrate Deposits at the GMGS2-Site 8, Pearl River Mouth Basin, South China Sea

Wang

et al. 2016

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Natural gas hydrate accumulations were confirmed in the Dongsha Area of the South China Sea by the Guangzhou Marine Geological Survey 2 (GMGS2) scientific drilling expedition in 2013. The drilling sites of verified the existence of a hydrate-bearing layer. In this work gas production behavior was evaluated at GMGS2-8 by numerical simulation. The hydrate reservoir in the GMGS2-8 was characterized by dual hydrate layers and a massive hydrate layer. A single vertical well was considered as the well configuration, and depressurization was employed as the dissociation method. Analyses of gas production sensitivity to the production pressure, the thermal conductivity, and the intrinsic permeability were investigated as well. Simulation results indicated that the total gas production from the reference case is approximately 7.3ˆ10 7 ST m 3 in 30 years. The average gas production rate in 30 years is 6.7ˆ10 3 ST m 3 /day, which is much higher than the previous study in the Shenhu Area of the South China Sea performed by the GMGS-1. Moreover, the maximum gas production rate (9.5ˆ10 3 ST m 3 /day) has the same order of magnitude of the first offshore methane hydrate production test in the Nankai Trough. When production pressure decreases from 4.5 to 3.4 MPa, the volume of gas production increases by 20.5%, and when production pressure decreases from 3.4 to 2.3 MPa, the volume of gas production increases by 13.6%. Production behaviors are not sensitive to the thermal conductivity. In the initial 10 years, the higher permeability leads to a larger rate of gas production, however, the final volume of gas production in the case with the lowest permeability is the highest.

“…The attractiveness of gas hydrates as a potential future energy source is increasing on account of the abundance of the resource and the growing global energy demands. There are four main methods for exploiting hydrate from hydrate accumulations: depressurization [3][4][5][6][7], thermal stimulation [8][9][10][11][12][13], inhibitor stimulation [14][15][16][17], and carbon dioxide replacement [18,19]. The depressurization method has received considerable attention for hydrate dissociation because of its easy operation and high energy efficiency.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Hydrate Dissociation Performance in the South China Sea with Different Horizontal Well Configurations

et al. 2014

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Based on the available measurement data and literature on the hydrate deposits of the South China Sea, a numerical simulation with a new dual horizontal well system has been carried out. Warm brine stimulation combined with depressurization is employed as the production method. Two horizontal wells were situated in the same horizontal plane and they were placed in the middle of the Hydrate-Bearing Layer (HBL). The warm brine is injected from the left well (LW) into the reservoir, and the right well (RW) acted as the producer under constant pressure. The simulation results show that the effects of hydrate dissociation rate, gas to water ratio, and energy ratio are all better than the previous work in which the dual horizontal wells are placed in the same vertical plane. In addition, the sensitivity analysis indicates that a higher injection rate can enhance the hydrate dissociation rate and gas production rate, while a lower injection rate gives a more favorable gas to water ratio and energy ratio.