页岩气解吸机理及输运特性的分形分析

Resources potentials of shale gas is very abundant in the whole world. Along with energy consumption and demand increasing,unconventional energy resource including shale gas has received more and more attention. In the next few decades, as a clean and efficient energy resource, shale gas may be a kind of conventional energy potential alternative energy sources. How to accelerate the exploration and development of the shale gas becomes the common desire for all countries in the world. Based on fractal theory, the project studies the physical mechanism of shale gas desorption as follows: (1) The quantitative relationship between shale gas desorption-rate and temperature, pressure, time will be obtained based on thermodynamics and statistical mechanics; (2) The gas competitive desorption mechanism considering multi-component adsorption in shale gas reservoirs will be studied; (3) The mathematical model of the relationship between the desorption-rate for shale gas and the microstructure of porous media and the physical mechanism of gas desorption will be investigated, and then fractal models for transport parameters such as predicting shale gas production will be developed. The project helps understanding the mechanism of shale gas desorption and its influencing factors. A fractal analytical model for shale gas desorption mechanism will be developed. At the same time, the result of this study may be useful for the reasonable and efficient exploration of shale gas reservoirs.

全球页岩气资源潜力巨大，随着能源消费与需求量不断攀升，包括页岩气在内的非常规能源越来越受到人们重视。在未来的几十年，页岩气作为一种清洁高效能源资源，可能成为常规能源的潜在替代能源,所以，加快页岩气资源勘探开发，已成为世界各国共同的愿望。本项目拟采用分形理论和方法，对页岩气解吸物理机理进行研究与探索，具体研究内容为：（1）利用热力学、统计物理学等相关理论，研究温度、压强及解吸时间与页岩气解吸速率之间的定量关系；（2）研究多组份吸附的页岩气解吸竞争机理；(3)基于多孔介质分形理论，研究与推导页岩气解吸速率与多孔介质微结构关系的物理机理和数学模型，建立能预测与求解页岩气产量等输运参数的分形模型。本项目的研究将有助于深刻理解页岩气藏里页岩气解吸机理与影响因素，预料本项目将提出一套较为完整的描述页岩气解吸特征参数的分形解析模型，为合理高效开发页岩气藏、提高其采收率提供重要的理论参考依据。

随着全球石油资源需求量不断增加以及常规油气资源可开采量不断下降，全球掀起了包含页岩气在内的非常规能源开发的热潮。页岩气作为一种清洁高效能源资源，可能成为常规能源的潜在替代能源，所以，加快页岩气资源勘探开发，对调整我国能源格局、缓解我国油气资源短缺,保障国家能源安全等具有重大意义。本项目以页岩气的解吸及传输特性为研究背景，采用分形理论与技术的方法，考虑了页岩气藏孔隙的结构特征和气体的稀薄效应，研究了页岩气在致密多孔介质中的输运特性，包含页岩气在页岩气藏/致密岩石中的扩散特性以及渗流特性。研究结果表明在考虑致密多孔介质孔隙结构收缩特征、弯曲特性及气体的Knudsen扩散效应，页岩气在致密多孔介质中的相对扩散率随毛细管幅度波动因子和面孔隙分形维数的增加而减少；页岩气在页岩气藏/致密岩石中的视渗透率不仅与页岩气藏围压及温度有关，而且还与页岩气藏孔隙结构的分布有关(孔隙率、孔隙面分形维数、孔隙的最大尺寸、迂曲度分形维数等)。