SCHEMES OF GAS PRODUCTION FROM NATURAL GAS HYDRATES

<正> Natural gas hydrates are a kind of nonpolluting and high quality energy resources for future, the reserves of which are about twice of the carbon of the current fossil energy （petroleum, natural gas and coal） on the earth. And it will be the most important energy for the 21st century. The energy balance and numerical simulation are applied to study the schemes of the natural gas hydrates production in this paper, and it is considered that both depressurization and thermal stimulation are effective methods for exploiting natural gas hydrates, and that the gas production of the thermal stimulation is higher than that of the depressurization. But thermal stimulation is non-economic because it requires large amounts of energy. Therefore the combination of the two methods is a preferable method for the current development of the natural gas hydrates. The main factors which influence the production of natural gas hydrates are: the temperature of injected water, the injection rate, the initial saturation of the hydrates and the initial temperature of the reservoir which is the most important factor. 1 Lei Huaiyan, Wang Xianbin. Current Situation of Gas Hydrates Research and Challenges for Future. Acta Sedimentological Sinica, 1999, 17 （3）2 Shi Dou, Zheng Junwei. The Status and Prospects of Research and Exploitation of Natural Gas Hydrate in the World. Advance in Earth Sciences, 1999, 14 （4）3 Chen Huifan4g. Prediction of the Conditions for the Forming of Natural Gas Hydrate. Journal of Xi'an Petroleum Institute, 1994, 9 （1）4 Yao Yucheng, Yin Fushan. Progressin Study of Natural Gas Hydrates. Progress in Chemistry, 1997, 9 （3）5 Zhao Shengeai. Current Situation of Gas Hydrate and Our ??Country's Policy. Advancein Earth Sciences, 2002, 17 （3）6 Zhou Huaiyang, Peng Xiaotong. Development in Technology of Prospecting and Exploitation for Gas Hydrates. Geology and Prospecting, 2001, 38 （1）7 Zhu Yuenian, Shi Buqing. Control Effects of Natural Gas Hydrates on Oil and Gas Accumulation and Reservoir Preservation. Natural Gas Industry, 2000, 20 （3）8 Wim J A M Swinkels, Rik J J Drenth. Thermal Reservoir Simulation Model of Production from Naturally Occurring Gas Hydrate Accumulations. SPE 565509 Moridis G J, Collett T S, Dallimore S R, Tohru Satoh. Numerical Studies of Gas Production from Several CH4-Hydrate Zones at the Mallik Site. LBNL 50257. Mackenzie Delta, Canada