Research Of Ggas Hydrate Testing Mining System And Numerical Simulation Of Thermal Method In Permafrost

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.