【摘要】 天然气在海底沉积层多孔介质中可能存在分形扩散行为 ,在此基础上 ,分析了沉积层中天然气水合物的形成原因。在公认的水合物形成的地质模型的基础上 ,提出了一个海底沉积层中天然气水合物的形成过程由气体的分形扩散过程主导的基本假设 ,并综合运用分形几何理论及经典扩散理论建立了一个新的水合物生成动力学模型。该模型描述出天然气水合物在分形介质中的扩散特性及生成动力学特性 ,并通过对分形维数的修正 ,进一步对水合物的形成速率方程进行了数值求解 ,分析了分形维数及扩散半径的改变对水合物形成速率的影响 ,并将所得结果与实验室数据及实地勘测数据进行了比较。预测了我国南海海下天然气水合物的储量 ,得到了一个比目前常规方法所预测结果偏小的储量预测值 ,并进一步对此进行了分析。更多还原

【Abstract】 Natural gas is of probably fractal diffusion action in the porous medium of submarine sedimentary strata.On the basis of this,the reason of forming gas hydrate in sedimentary strata is analyzed in the paper.In consideration of the accepted geological model of gas hydrate formation,a basic hypothesis,that the formation course of gas hydrate in submarine sedimentary strata was predominated by the gas fractal diffusion action,was proposed and a new hydrate formation dynamic model was set up by applying fractal geometric theory and classical diffusion theory.By the model,the gas hydrate diffusion property in fractal medium and its formation dynamic characteristic were described;through correcting the fractal dimension (df),the numerical solving was further carried out for the hydrate formation rate equation;and the influence of the fractal dimension (df) and diffusion radius (r) on the hydrate formation rate was analyzed and the results obtained were compared with the experimental data and on-site surveying data.In South China Sea,the submarine gas hydrate reserves predicted by this model are smaller than those estimated by the conventional methods at present.The reason is futher analyzed in the paper.更多还原