Studies On The Formation Affecting Factor And Stability Of Natural Gas Hydrates

The development of natural gas hydrate storage and transportation technology is favorable for the recovery of offshore associated gas fields and the development of scattered gas field, but the technology still has a number of issues that need to be solved. This paper did experimental researches on the physical appearance, formation affection factors and stability of hydrates, and laid foundations for industrial application.The major work of this paper includes: experimental device design, physical appearance test, formation and storage experiments of hydrate, storage device design, storage and transportation technology and its economical analysis, etc.Experimental study was done on gas-bearing ratio, specific heat and flammability of hydrates. Density of hydrates measured in the experiment is during 0.8～0.95g/cm3. Specific heat of hydrates is small, which is 2.1J.g-1.℃-1 at the temperature of -20℃. Explosion will never happen during hydrates combustion due to the influence of decomposition rate. Many factors have impact on the formation of hydrates. In a certain range, the higher the pressure and the lower the temperature are, the higher the gas-bearing ratio of the formed hydrates will be. During a certain time, the gas-bearing ratio of hydrates increases with reaction time. Compared with pure water, the addition of sodium dodecyl sulfate can greatly increase the formation rate of hydrates. Water history can reduce the induction time of hydrates formation, but its influence is relatively small. Stirring can increase the formation rate of hydrates. Influences of temperature, pressure and compaction on the stability of hydrates and atmospheric storage at different temperature (low temperature) were studied. The decomposition rate of hydrates is relatively small after self-protection works. Pressure and compaction can improve the hydrates stability. Onshore storage and transportation technology is studied preliminarily, and is compared with other transportation methods at technological, safe and economical aspects. Hydrates technology has certain advantages, but as a new technology, it still needs further development and study.