多孔介质中天然气水合物分解过程传热分析

发布时间：2018-03-28 13:41

本文选题：天然气水合物　切入点：分解　出处：《大连理工大学》2014年硕士论文

【摘要】：天然气水合物资源储存量大,能量密度高、环境友好。对于其开采目前面临众多技术性及安全性问题。天然气水合物分解是一个吸热过程,热量传递直接影响水合物分解速率和分解进程,对天然气水合物分解过程传热分析对水合物开采的高效性及安全性有重要意义。因此,本文通过数值模拟方法对多孔介质中天然气水合物分解过程传热进行分析。本文利用一个二维轴对称水合物分解模拟器,对水合物分解时各传热因素的影响进行分析。对控制传热的参数进行分离,分类对含水合物多孔介质中的导热、含水合物多孔介质层与上下盖层之间的导热、含水合物多孔介质中的对流换热以及含水合物多孔介质层的显热等传热因素对多孔介质中甲烷水合物分解进程的影响进行了系统分析,通过对天然气水合物产气以及不同分解时刻压力、温度及水合物饱和度分布等数据进行整理,揭示了多孔介质中天然气水合物降压、注热、以及联合开采传热控制机理。研究结果表明：1、较高的多孔介质导热,在多孔介质水合物降压分解中有限的促进水合物的分解；在多孔介质水合物注热分解及联合开采初期并不利于多孔介质中水合物分解,但在后期能使迅速分解整个区域内水合物缩短整体反应时间。2、含水合物多孔介质层与上下盖层之间的导热,在没有外界额外热量注入的多孔介质水合物降压分解中是主控因素。3、含水合物多孔介质中的对流换热,对多孔介质水合物降压分解一定的影响；对多孔介质水合物注热分解及联合开采影响甚微。4、多孔介质层的显热的研究分为多孔介质比热容和多孔介质中含水量两方面分析。在多孔介质水合物降压分解中,较高的比热容为含水合物多孔介质提供更多的显热,促进水合物的分解,较多的水反而阻碍了水合物分解及产气；在多孔介质水合物注热分解及联合开采时,较高的多孔介质比热容和水含量贡献了较多的显热但阻碍了热量在多孔介质中传递,进而阻碍了水合物分解。
[Abstract]:The natural gas hydrate resource has a large amount of storage, high energy density and environmental friendliness. At present, the gas hydrate decomposition is an endothermic process, which is faced with many technical and safety problems at present. Heat transfer directly affects the rate and process of hydrate decomposition, and it is of great significance to the efficiency and safety of hydrate extraction by analyzing the heat transfer during the decomposition process of natural gas hydrate. In this paper, the heat transfer of gas hydrate decomposition in porous media is analyzed by numerical simulation. In this paper, a two-dimensional axisymmetric hydrate decomposition simulator is used to analyze the influence of heat transfer factors on hydrate decomposition. Heat conduction between the porous media layer containing hydrate and the upper and lower caprocks, The effects of heat transfer factors such as convection heat transfer in porous medium containing hydrate and sensible heat in porous layer of hydrate on the decomposition process of methane hydrate in porous medium are systematically analyzed. Based on the data of gas hydrate production, pressure at different decomposition times, temperature and hydrate saturation distribution, the mechanism of gas hydrate pressure reduction, heat injection and heat transfer control for combined exploitation in porous media is revealed. The results show that the higher heat conduction of porous media promotes the decomposition of hydrates in the decompression of hydrates in porous media, and the decomposition of hydrates in porous media is not beneficial to the decomposition of hydrates in porous media at the initial stage of gas hydrate injection and combined exploitation. However, in the later stage, the rapid decomposition of hydrates in the whole region can shorten the overall reaction time of 0.2, and the heat conduction between the porous media and the upper and lower caprocks of the hydrates can be obtained. In the decompression of hydrate in porous medium without extra heat injection, the main controlling factor is .3.Convective heat transfer in porous medium containing hydrate has a certain effect on the decompression of hydrate in porous medium. The study on the sensible heat of porous media layer can be divided into two aspects: specific heat capacity of porous medium and water content in porous medium. The higher specific heat capacity provides more sensible heat for the porous medium containing hydrates and promotes the decomposition of hydrates, but more water hinders the decomposition of hydrates and gas production. Higher specific heat capacity and water content of porous media contribute more sensible heat, but hinder heat transfer in porous media, which hinders hydrate decomposition.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P744.4

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