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室内模拟合成水合物沉积物样品是开展水合物研究的一个重要途径,但实验方式耗时且不易控制。数值模拟技术则能够比较方便定量地控制水合物形成条件,快速模拟其形成过程。据此采用实验室常用的恒容法模拟研究了水浴降温条件下,室内沉积物中天然气水合物的形成过程,进一步揭示了其形成和分布规律。研究结果表明,在混合均匀的气—盐水体系中,能够合成相对均匀分布的水合物模拟地层样品。但在体系温压条件趋于稳定后,仍需维持较长的反应时间来促使体系反应的最终完成。当体系中存在薄“夹层”(主要是指模拟介质中间区域的渗透率和孔隙度发生变化)时,薄“夹层”的渗透率和孔隙度都会对系统中水合物的形成过程产生一定的影响,但最终系统中的水合物饱和度分布与无夹层时基本相同,这可能是由于采用恒容法形成水合物,前期水合物生成速率快,多孔介质中的薄“夹层”对体系传质影响显著,后期由于反应速率变慢,其影响相对较小,在维持较长的反应时间后,趋于一致。
Indoor simulation of synthetic hydrate sediment samples is an important way to carry out hydrate research, but the experimental method is time-consuming and difficult to control. The numerical simulation technique can conveniently and quantitatively control the hydrate formation conditions and quickly simulate the formation process. Based on this, the formation of natural gas hydrate in indoor sediments and the formation and distribution of gas hydrate under the condition of water bath cooling were studied by the constant volume method commonly used in laboratory. The results show that in the mixed gas-brine system, a relatively uniform distribution of hydrate simulated formation samples can be synthesized. However, after the temperature and pressure conditions of the system tend to be stable, it still needs to maintain a longer reaction time to promote the final completion of the system reaction. The permeability and porosity of thin-walled “sandwiches” can affect the hydrate formation in the system when there is a thin “interlayer ” in the system (mainly referring to changes in permeability and porosity in the middle of the simulated medium) However, the distribution of hydrate saturation in the final system is basically the same as that of the non-interbed, which may be due to the formation of hydrate by the constant volume method, the early hydrate formation rate and the thin "Significant impact on the mass transfer system, the latter because the reaction rate is slow, the impact is relatively small, to maintain a longer reaction time, tend to be consistent.