Unlike conventional oil and gas sources, natural gas hydrate (NGH) is stored in solid form within the pores of loose submarine sediments. Production by any method poses a complex problem involving phase transition and multi-phase flow of gas and water. The evolution of hydrate dissociation from the solid phase to gas and liquid phases in a hydrate reservoir is a dynamic process incorporating pore structure and multi-phase seepage. The solid–gas-liquid phase dissociation of NGH affects reservoir seepage properties by altering the micropore structure of the hydrate-bearing sediments. This study, based on the lattice Boltzmann method of modeling fluids flow, clearly demonstrates the micropore-scale changes in pressure and heat transfer that take place during hydrate dissociation. Pore-scale heterogeneity is found to influence the complex development of hydrates in a porous clayey silt medium during dissociation. The effect of hydrate, gas and water saturation on the evolution of relative permeability is identified, and the relationship between relative permeability and hydrate saturation during hydrate dissociation is quantified. These findings provide theoretical support for the implementation of marine natural gas hydrate production testing and future commercial production in China.

中文翻译：

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含水合物粘土粉砂沉积物水合物解离过程中多相渗流参数动态演化的孔隙尺度研究

与传统的石油和天然气来源不同，天然气水合物（NGH）以固体形式储存在松散的海底沉积物的孔隙中。任何方法的生产都会带来涉及气体和水的相变和多相流的复杂问题。水合物储层中水合物解离从固相到气液相的演化过程是一个结合孔隙结构和多相渗流的动态过程。水合物的固-气-液相解离通过改变含水合物沉积物的微孔结构来影响储层渗流特性。这项研究基于模拟流体流动的格子玻尔兹曼方法，清楚地证明了水合物解离过程中发生的压力和传热的微孔尺度变化。研究发现，孔隙尺度的非均质性会影响多孔粘土粉砂介质中水合物解离过程中的复杂发育。确定了水合物、气体和水饱和度对相对渗透率演变的影响，并量化了水合物解离过程中相对渗透率与水合物饱和度之间的关系。这些研究结果为我国实施海洋天然气水合物生产试验和未来商业化生产提供了理论支撑。