Investigation into gas production from natural gas hydrate: A review

Abstract

Natural gas hydrates (NGHs), which extensively exist in sea-floor and permafrost regions, are considered as an alternative energy in the future for the fossil fuels approaching depletion with the gradually increasing energy consumption. Because of the particularity of NGH stabilizing only in the conditions of the high pressure and the low temperature, the exploitation of NGH is distinguished from those of petroleum and natural gas. Researchers over the world are devoting themselves to developing the technologies of NGH exploitation. However, till now, few NGH exploitation technology is identified and employed to exploit commercially NGH. Although there do be two cases of short-term NGH exploitation in Mackenzie Delta (CAN), Alaska North Slope (USA) and Nankai Trough (JAP) in the past 10 years. It is mainly because some characteristics of the flow (gas, water, gas-hydrate slurry, quicksand, etc.), the issues of heat and mass transfer, the risk assessment and the economic evaluation are still not comprehensively recognized. Presently, the researches of NGH exploitation are mainly carried out from three aspects, numerical simulation and analysis, experimental simulation and field trial exploitation for the different technologies. In this paper, we comprehensively review the relevant studies of NGHs and propose our comments. We not only represent the achievements for the NGH exploitation researches, but also discuss the limitations and challenges, raise some questions and put forward some suggestions from our points of view.

Review of exploration and production technology of natural gas hydrate

“…efficiency of gas production, lowering the energy consumption, accelerate the gas production, etc. Compared with thermal stimulation or depressurization, the combination technique is proven to be more efficient in natural gas production from NGH reservoirs (Li et al, 2016).…”

“…From the thermodynamic point of view, both pure CO 2 and CH 4 molecules typically form hydrates under corresponding conditions, and the enthalpy of CO 2 hydrate formation (about -57.98 kJ/mol) is lower than that of CH 4 hydrate formation ( -54.49 kJ/mol). It means CO 2 hydrate is more stable than CH 4 hydrate under the same condition of temperature and pressure (Li et al, 2016). Yuan (2012) proposed a conceptual mechanism for CO 2 -CH 4 replacement in hydrate-bearing sediments.…”

Multiphase Flow Behavior of Layered Methane Hydrate Reservoir Induced by Gas Production

“…Multiple methods have been proposed and employed to decompose hydrate for gas recovery from the HBS, such as depressurization, thermal stimulation, gas exchange, and the use of hydration inhibitors (such as salts and alcohols) [2,[5][6][7][8]. The above methods have been compared in terms of energy efficiency, economic and technological feasibility, and environmental performance [1,4,9,10].…”

Numerical Investigation of the Production Behavior of Methane Hydrates under Depressurization Conditions Combined with Well-Wall Heating

“…Several efficient and feasible gas recovery methods for in-situ CH 4 recovery from the hydrate reservoirs have been proposed, such as hot water injection [4,5], in situ combustion [6,7], depressurization [8][9][10][11], inhibitor injection [12,13], CO 2 replacement [14,15] and the combined methods [16][17][18][19][20]. Using these technologies, extensive research on natural gas production from hydrate in field trials has been conducted within the last decade [21][22][23][24][25]. Natural gas has been successfully extracted by injection of hot water and by depressurization at the permafrost reservoir of the Mallik site in Northwest Canada [21].…”