The study of natural gas migration and accumulation of tight gas has become the focus of the energy industry in recent years. One of the priorities is the research of hydrocarbon migration carrier system of the formation. This study reveals two types of hydrocarbon carrier systems (micro-fractures and micro-coal lines) in the tight formation through a large amount of geological observations, data statistics, and simulations. This study also first put forward the view that the coal lines can be a type of hydrocarbon carrier system in tight sandstone formation. During the research process, an improved permeability testing method and apparatus are used to test the core permeability widely. Based on the real core, three models are established to describe the micro-fracture/micro-coal line characteristics. According to the three typical models, the Voronoi method is used to rebuild the network models. The migration and accumulation process in tight formation is simulated with the Multiple Relaxation Time lattice Boltzmann method in numerical simulation and with displacement apparatus in physical simulation. The results indicate that the micro-fracture/micro-coal line will significantly improve the percolation capacity of sandstone as the hydrocarbon migration carrier system in tight formation, the mechanism is revealed by numerical simulations. The micro-fractures/micro-coal lines are favorable for natural gas accumulation in tight formation. Unlike the conventional formation, in tight formation, micro-fractures/micro-coal lines tend to be the main migration carrier systems during the gas accumulation process.

中文翻译：

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四川盆地三叠系须家河组微裂缝和微煤线对致密气成藏的影响

近年来，天然气运移与致密气成藏研究已成为能源行业的热点。地层油气运移输送系统研究是重点研究内容之一。本研究通过大量地质观测、数据统计和模拟，揭示了致密地层中两种类型的油气运载系统（微裂缝和微煤系）。本研究还首次提出煤系可以作为致密砂岩地层中的一种油气输送系统的观点。研究过程中，采用改进的渗透率测试方法和装置，对岩心渗透率进行了广泛的测试。基于真实岩心，建立了三个模型来描述微裂缝/微煤线特征。根据三种典型模型，采用Voronoi方法重建网络模型。数值模拟中采用多重弛豫时间格子玻尔兹曼法，物理模拟中采用驱替装置模拟致密地层中的运聚过程。结果表明，微裂缝/微煤线将显着提高砂岩作为致密地层油气运移载体系统的渗流能力，数值模拟揭示了其机理。微裂缝/微煤系有利于致密地层天然气的聚集。与常规地层不同，在致密地层中，微裂缝/微煤线往往是天然气成藏过程中主要的运移输送系统。