Abstract:

Gas production from hydrate reservoir by depressurization is considered the most feasible approach up to date.However, the study on the theory and law of production is fairly scarce.In this paper, experimental work of the decomposition of methane gas hydrate by depressurization in porous media was carried out with the 1D experimental apparatus.A one-dimensional mathematic model was built, which considered natural gas hydrate dissociation kinetics and flow inporous media.This model was used to fit the experimental data, and the derived intrinsic dissociation kinetics constant was in the order of 10 mol·m^-2·Pa^-1·s^-1, which was three orders of magnitude lower than that derived from bulk hydrate dissociation.The model also suggested that the hydrate dissociation kinetics had a great effect on the gas production behavior for the laboratory scale hydrate reservoir.However for a field scale reservoir, the hydrate dissociation kinetics had little effect while the flowability dominated the gas production behavior.

Key words:

天然气水合物, 降压分解, 数值模拟

摘要：

在天然气水合物一维分解模拟系统上进行模拟多孔介质中水合物降压分解的实验。在考虑天然气水合物分解动力学机理以及流体渗流模型的基础上;建立天然气水合物降压分解的数学模型。利用模型对降压实验进行拟合;获得了多孔介质内水合物分解本征速度常数数量级为10 mol·m^-2·Pa^-1·s^-1;比文献中测定的纯水中水合物分解本征速度常数低3个数量级。对模型进行了参数分析;发现对于实验室规模的一维系统;分解动力学过程控制整个分解过程;而对于现场规模的水合物藏;整个开采过程受水合物藏流动特性的控制;而受水合物分解过程的影响较小。

关键词:

天然气水合物, 降压分解, 数值模拟