Experimental Studies On Exploitation Feasibility Of Natural Gas Hydrate By Thermal Stimulation And Depressurization

Natural gas hydrate (NGH) new-style energy discovered in the ocean and the frozenearth during the past20years. NGH is known as the highest commercial developmentpotential resource. The geological condition and physical parameters of NGH is differentaroud the world. Different styles of NGH necessarily result in different mining methods. Inthis thesis, we use the one-dimension NGH exploitation experimental simulation system tostudy the exploitation feasibility of NGH by thermal stimulation and depressurization.By depressurizing exploitation of NGH, we can find that: When NGH saturation ishigher and the initial temperature is lower, the NGH self-preservation can occur duringdepressurization. While the coefficient of heat conductivity of the reaction kettle is large, theself-preservation can disappear immediately and NGH continue to decompose. As NGHsaturation higher, the average gas production rate will increase firstly then reduce later. Theorthogonal experiments show that the factors which influence the of NGH depressurizationdissociation are NGH saturation, initial temperature and outlet pressure in turn. Consideringthe real heat transport of NGH, the middle saturation and the higher initial temperature canlead to higher exploitation feasibility for slow depressurization.By thermal stimulation of NGH, we can find that: the thermal stimulation experimentcan be divided into four stages, the production performance is different when the amount ofhot-brine injection is different. Univariate analysis shows that the higher NGH saturation,higher initial temperature and lower hot-brine temperature can result in higher energyefficiency. The energy efficiency will increase firstly then reduce later with hot-brine injectionrate increasing. The factors which influence the energy efficiency of NGH thermaldissociation are hot-brine temperature, NGH saturation, initial temperature, hot-brineinjection time and hot-brine injection rate in turn. The higher NGH saturation and higherinitial temperature will result in higher energy efficiency, but permeability is low when NGH saturation is too high and influences the hot-brine injection, thermal parameters should beoptimized reasonably for NGH thermal dissociation.