【作者】 房治强；

【导师】 陈晨；

【作者基本信息】 吉林大学 ， 地质工程， 2011， 硕士

【摘要】 进入二十一世纪的中国,经济的发展已是日新月异,所以对于能源的需求也是与日俱增。作为常规能源的煤、石油及天然气已经满足不了经济的快速发展；同时常规能源的无节制使用也造成了诸多环境问题,因此寻求高效节能的能源己被我国所重点关注。天然气水合物就是一种高效洁净的能源,其特点是分布较广、资源量相对巨大、埋藏浅、存储层规模大、能量密度高等。我国又是世界第三大冻土区,冻土面积约215万km2,具备良好的天然气水合物形成的条件,粗略估算冻土区水合物资源量至少有350亿吨油当量,因此多年来对于天然气水合物的开发与利用都是我国所致力研究的问题。然而有效的开采方法一直是困扰着对其大规模利用的关键所在；对天然气水合物开采理论上已有几种方法：降压法、热激法、注入抑制剂法及理论上的CO：置换法。但是每种方法都有其缺点和局限性；本文在调研了国内外有关天然气水合物开采的数值计算以及有限元模拟基础之上,充分考虑了天然气水合物的热激法开采的机理,通过模拟计算改变开采介质的温度、压力和流速以及作用时间等开采参数来辨别影响天然气水合物开采的主要因素。本文首先建立数学模型,利用数值计算方法推导出开采天然气水合物所需的能量；其次详细介绍了由吉林大学自主研发的天然气水合物试开采系统及采气系统的工作原理以及对开采系统和采气系统的调试工作；第三有限元模拟；通过对影响天然气水合物开采的温度、压力、流速及作用时间四者的有效组合模拟优化出适合热激法开采天然气水合物的理论参数；同时依据青海木里盆地天然气水合物地层参数和吉林大学自主研发的天然气水合物试开采系统的设备能力进行有限元模拟参数设置,以达到理论模拟与实际的有效结合,模拟优化出适合冻土区热激法开采的工艺参数。通过上述的工作本文得到了温度是热激法开采水合物的主导因素,同时过高的温度也会带来压力的增大,反而抑制了水合物的分解,所以要将温度与压力同时考虑以作优化。通过优化得出当温度为80℃,压力8MPa,流速为2m/s时热流体影响的半径最大,其水平影响半径可达6.75m。同时将热流体加热至热蒸汽时开采效果更佳,主要是热蒸汽与水合物作用时首先是由气相变为液相时放出大量的热,其次变为液体时在常温常压下仍是100℃的热水,与80℃的热水相比具有更高的能量。但用热蒸汽开采时要充分考虑设备的承受能力。更多还原

【Abstract】 Resource of gas hydrate of permafrost region is a great reserve, and this is a fact recognized by the world. At present China was the world’s third largest country that possessed of gas hydrate. Total areas of frozen soil were 2,150,000 square kilometers, owning good conditions and resources to form natural gas hydrate. According to scientists estimated, the amount of long-term resources was at least 350 tons of oil.Into the twenty-first century, China’s economic development was very rapid. So the demand of energy was growing as well. Therefore conventional energy sources such as coal, oil and natural gas had failed to meet the rapid economic development. At the same time the uncontrolled use of conventional energy sources also caused many environmental problems, so searching for energy-efficient has been a hot topic in the world.Gas hydrate is a clean and efficient energy. Its characteristic is widely distributed, a huge amount of resources, shallow reservoir scale, high energy density and so on. Therefore development and exploitation of natural gas hydrate has been committed to the countries of the world’s problems over many years. However, the key of the problem was how to use it at large scales. The theory of exploitation has several methods, such as depressurization, thermal exploration, inpouring depressor and CO2 replacement. But each method has its drawbacks and limitations. This paper based on the research of the domestic and foreign exploitation of gas hydrates and finite element numerical simulation. By fully considered the regular of natural gas hydrate exploration in the mechanism of thermal excitation and with fully consider of Muli basin of Qinghai city, the major parameters of impact of exploitation were identified by changing the simulation temperature and pressure of gas hydrate and the heat fluid flow velocity and time.Firstly, a mathematical model was built. Then derived the energy required for gas hydrate by simulated conditions. Secondly, described exploration system, gas extraction system and the system of commissioning and debugging work by the self-test in detail. Thirdly, finite element simulation analyzed the exploitation of gas hydrate on the impact of temperature, pressure, velocity and time effective combination of the four simulation optimization methods suitable for thermal excitation of the theoretical parameters of Gas Hydrate. Jilin University combined with self-developed system of trial extraction of gas hydrates in laboratory parameters collecting by finite element simulation of mining parameters to correct to achieve the theoretical simulation and the effective integration of the actual experiment. Simulation and optimization the permafrost thermal excitation method was provided mining process parameters.Temperature was the dominant facto of thermal excitation in gas hydrate exploration. While high pressure would also decrease the temperature which would inhibits the decomposition of gas hydrate. Therefore considering temperature with pressure for optimization, Obtained optimizing parameters were the temperature 80℃, the pressure 8MPa, the flow velocity 2m/s. The maximum radius of impact of thermal fluids and its level of influence radius was up to 6.75m. If heating up fluid to vapour it would be better than that of fluid. Because the gas deliquesce into liquid would released quantity of heat.At the same time liquid at room temperature and atmospheric pressure was still 100℃hot water, compared with 80℃hot water, it had more energy. However, when using the hot vapour the extraction equipment needed to consider the bearing capacity.更多还原