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岩石扩散系数是岩石固有的基本物理量之一，是研究天然气扩散最重要的参数。前人用实验室实测数据求取系数，致使实验时间过长（达千余小时），并存在某些不确定因素；或是在封闭式实验中使用稳定模型处理非稳态的扩散实验过程，导致所求取的扩散系数值产生了大约一个数量级的偏差（误差为１／２～４倍）。在总结了前人经验的基础上，由扩散理论与数学模型相结合的方法，推出了用实测数据求取扩散系数的非稳态模型，并获得了解析解。通过理论分析和大量的实测资料的反复对比计算表明：用该非稳态模型所处理的实测数据，能很好地反映实验中天然气通过岩样的扩散规律。该方法不仅能纠正前人模型所产生的严重偏差，并且可以在不改变原有封闭式实验装置和实验方法的条件下，极大地提高所测岩样的扩散系数精度，同时将原有实验时间缩短至两小时至数小时范围内，从而降低实验成本，提高实验效率，该方法具有较高的推广应用价值。
Rock diffusion coefficient is one of the basic physical quantities inherent in rock and is the most important parameter for studying natural gas diffusion. The predecessors used the laboratory measured data to get the coefficient, resulting in the experiment time is too long (up to more than 1,000 hours), and there are some uncertainties; or in a closed experiment using a stable model to deal with the non-steady state diffusion experiment process, Resulting in a deviation of about one order of magnitude (1/2 to 4 times the error) of the calculated diffusion coefficient value. On the basis of summarizing the experience of predecessors, a non-steady-state model for calculating diffusion coefficient with measured data is introduced and an analytical solution is obtained by a combination of diffusion theory and mathematical model. Through theoretical analysis and repeated comparison calculation of a large number of measured data, it is shown that the measured data processed by the unsteady model can well reflect the diffusion law of natural gas passing through the rock sample in the experiment. The method can not only correct the serious deviation caused by the former model, but also can greatly improve the diffusivity of the measured rock sample without changing the original closed experimental device and experimental method. Meanwhile, the original experimental time Shortened to two hours to several hours range, thereby reducing the experimental costs and improve the efficiency of the experiment, the method has a high value of popularization and application.