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

Climate Change 1995 is a scientific assessment that was generated by more than 1 000 contributors from over 50 nations. It was jointly co-ordinated through two international agencies; the World Meteorological Organization and the United Nations Environment Programme. The assessment was completed by the Intergovernmental Panel on Climate Change (IPCC) with a primary aim of reviewing the current state of knowledge concerning the impacts of climate change on physical and ecological systems, human health, and socioeconomic factors. The second aim was to review the available information on the technical and economic feasibility of the potential mitigation and adaptation strategies.

Climate Change 1995

Hydrogen production for energy: An overview

Annual Energy Outlook

By L I Sedov London: Cleaver-Hume Press Ltd Pp xvi + 363 Price 105s This is really two separate books within the same pair of covers First of all Chapters 1-3, some 145 pages, are devoted to the discussion of similarity and dimensional, methods and their application to a variety of problems in mechanics and fluid mechanics

http://iopscience.iop.org/article/10.1088/0031-9112/11/6/008/pdf

Similarity and Dimensional Methods in Mechanics

The invention discloses an experiment device for conducting multiphase separating on natural gas hydrate well drilling liquid. The experiment device comprises a solid phase separator, a liquid injection module, a gas injection module and a gas-liquid separator. The solid phase separator comprises a first filtering device and a second filtering device. The gas injection module injects gas into the solid phase separator. The liquid injection module injects liquid into the solid phase separator. The gas-liquid separator communicates with the solid phase separator through a pressure control valve. The invention further discloses an experiment method through the experiment device. According to the experiment device and method for conducting multiphase separating on the natural gas hydrate well drilling liquid, the liquid injection module and the gas injection module are combined, so that the solid phase separator is always in a gas-liquid mixing high pressure state, multiphase separating of the natural gas hydrate well drilling liquid is achieved under the high pressure, and meanwhile, the situation that new hydrate is generated by the well drilling liquid in the separating process is avoided; and solid particles in the well drilling liquid can be effectively removed through the double filtering devices in the solid phase separator, so that the device is prevented from being blocked.

Experimental device and method for conducting multiphase separation on natural gas hydrate well drilling liquid

Gas hydrate decomposition in sediments involves complicated multiphase flow and heat and mass transfer processes because of heat absorption by solid hydrates. Factors affecting gas hydrate decomposition in sediments include sediment type, mineral composition, pore size distribution, particle size, pore water composition, hydrate saturation distribution, initial formation pressure and temperature and cement characteristics. In this paper, experimental simulations of gas hydrate decomposition are carried out on an artificial core to investigate the effects of initial pressure and temperature, particle size and pore size. The experiments show that the characteristics of gas hydrate decomposition in sediments differ completely from those in a pure water system. The decomposition rate of hydrate sediments increases with the initial pressure increasing and decreasing temperatures. Furthermore, the decomposition rate of hydrate sediments decreases with decreasing particle size and increasing pore size.

Experimental simulation of gas hydrate decomposition in porous sediment

Study on the temperature characteristics in the process of cyclopentane-methane binary hydrate formation with a set of large-scale equipment

Decomposition behaviors of methane hydrate in porous media below the ice melting point by depressurization

China conducted an offshore gas production test at the site SHSC2-6 in the Shenhu Area of the South China Sea in 2020. The geosystem and key parameters of this site, including the water depth, thickness of the hydrate and the free gas layers, pressure and temperature at key locations, and sediment porosity and permeability, are currently available. The hydrate dissociation is induced by depressurization through a single horizontal well located in the hydrate-bearing layer (HBL). The underlying free gas layer (FGL) below the HBL makes it a “two-gas co-production” (natural gas hydrate and shallow gas) process. A novel numerical simulation code, the full implicit simulator of hydrate (FISH), is employed to develop the mathematical model and reproduce the 42 day field test in this marine hydrate reservoir. During the simulation, a permeability reduction model is used to fit the hydrate-bearing and the hydrate-free permeability in the field test. After strict history matching of the field test results (the mean absolute percentage error of gas production is 2.264%), we predict the long-term gas production behavior, including the gas and water production and the spatial distribution of pressure, temperature, phase saturations, etc. The results of the 8 year simulation indicate that the average gas production rate is 2.323 × 104 m3/day and the methane/water ratio is in the range of 50–120. This preliminary evaluation suggests that the hydrate deposits in the Shenhu Area are an unattractive production target with current technology. The main reason for this poor performance of gas production is the limited saturation of the free gas (smaller than 15%) in the hydrate reservoir. A future geological survey should focus on finding hydrate reservoirs with high gas saturation and large gas effective permeability. A key finding of this study is that the bottleneck of hydrate dissociation in the deposits is the low temperature caused by its own cooling effect. A thermal-assisted depressurization method is recommended as a potential strategy of gas recovery from marine hydrate reservoirs. 

Xiao-Sen Li

Papers

Experimental device and method for conducting multiphase separation on natural gas hydrate well drilling liquid

Experimental simulation of gas hydrate decomposition in porous sediment

Study on the temperature characteristics in the process of cyclopentane-methane binary hydrate formation with a set of large-scale equipment

Decomposition behaviors of methane hydrate in porous media below the ice melting point by depressurization

Long-Term Analysis of the 2020 Gas Hydrate Production Test in the South China Sea by Full Implicit Simulator of Hydrate