海底沉积层中水合物成藏过程模拟

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	海底沉积层中水合物成藏过程模拟
其他题名	The Formation Process Simulation of Hydrate Reservoirs in Seafloor Sediments
	关进安
导师	樊栓狮.华南理工大学 ; 梁德青.中国科学院广州能源研究所
	2008-08-28
学位授予单位	中国科学院研究生院
学位授予地点	北京
学位名称	博士
学位专业	热能工程
关键词	水合物动态成藏渗漏型游离气多相流资源量 Hydrate Dynamic Formation Seeping Type Free Gas Multiphase Flow Resource
摘要	Classification on natural gas hydrate deposits is summarized in this paper, and a dynamic theory of gas hydrate reservoirs formation is put forward. Based on this theory, there have three types of reservoirs: growing type(including seeping type and diffusing type), matured type and regressive type. Some experiments have been done by simulating in-situ hydrate formation system when gas migrating in seepage system in a glass bubble cell. The phenomena in experiments indicate that gas migration can change the quality of mass and heat transfer when hydrate forming. There may exist a “pseudo” buffer layer which has some distance of thickness in the interface between gas and liquid. The overburden stress in sediments capillary will gradually breed because of continuously hydrate formation in the course of gas migration, and causes faults or fractures of the stratum matrix. Therefore, it must build up new hydrate phase diagram in order to adapt the new characteristic of natural hydrate system brought by gas migration. Assuming there has a methane venting zone of 1500m, and the methane flux is 1000kmol/a, and the temperature of methane hydrate-bearing sediments ranges from 3℃ to 20℃, then according to the hydrate film growth theory, by numerical simulation,the results show that the cementation velocity in sediments matrix of methane hydrate is about 0.2nm/s, and the seepage system will evolve into diffusion system over probably 35ka. Meanwhile, the methane hydrate growth velocity in leakage system is about 20-40 times faster than in diffusion system. A multi-phase flow model including water - gas (free gas) –salt- hydrate has been eatablished to describe this flow-transfer-reaction process. Combinating informations gotten from in-situ drilling samples datum, the methane formation process in Shenhu area of South China Sea has been deducted. It has been speculated that there has a moderate methane flux over this seafloor sediment. If the flux is about 0.5kg/m2·a, then it has evoluted about 4800a through simulation, and after about 2700ka, the hydrate saturation in pore will arrive its peak. Approximately 1.47×109m3 methane hydrate volume has been estimated in this marine basin.
其他摘要	水合物成藏是一种动态演变过程，从生成和分解速度相对大小角度提出了天然气水合物的动态成藏理论；分析指出天然气水合物储层状态主要存在三种类型：成长型（包括渗透型与扩散型）、成熟型和消退型，必须结合经济型指标对这三种类型水合物藏进行开采可行性研究。通过在自制的透明鼓泡反应釜内模拟气体迁移与水合物形成实验，解释了气体迁移对体系内传热与传质、溶解性质、过压等的影响因，进一步指出需要研究新的水合物相图。从传热角度建立了水合物生长模型，计算并比较了南海北部陆坡琼东南盆地里甲烷水合物在渗漏系统和扩散系统下的生长速度，指出前者比后者快约20-40倍。建立了水-气（游离气）-水合物-盐反应的多相流模型，演绎了在四个不同时刻随着水合物的形成，溶解度、渗透率、毛细压力、饱和度及盐度等的联动演变关系，并分析和比较了在沉积层水合物稳定区域内不同游离气饱和度和甲烷渗漏通量情况下水合物的形成过程和三种成藏类别。反演了神狐海域水合物的形成，指出该区很可能是属于发育阶段的成长型渗漏系统水合物储藏，按照甲烷渗漏通量为0.5kg/m2·a计算，该地区已演化了约4800a，还需要约2700ka孔隙中水合物可到最大体积饱和度，达约75%，并在此后游离气将溢出沉积层进入海水中；计算得最终的甲烷水合物储量约为1.47×109m3，即该区最终将储存着约2200亿立方米甲烷气，是现在预测的约13倍！
学科领域	热能工程
页数	共136页
文献类型	学位论文
条目标识符	http://ir.giec.ac.cn/handle/344007/1773
专题	中国科学院广州能源研究所天然气水合物基础研究实验室
推荐引用方式 GB/T 7714	关进安. 海底沉积层中水合物成藏过程模拟[D]. 北京. 中国科学院研究生院,2008.