The Upper Triassic Xujiahe Formation is a typical tight gas reservoir in which natural fractures determine the migration, accumulation and production capacity of tight gas. In this study, we focused on the influences of natural fractures on the tight gas migration and production. We clarified characteristics and attributes (i.e. dips, apertures, filling degree and cross-cutting relationships) of the fractures based on image logging interpretations and core descriptions. Previous studies of electron spin resonance, carbon and oxygen isotopes, homogenization temperature of fluid inclusions analysis and basin simulation were considered. This study also analysed the fracture sequences, source of fracture fillings, diagenetic sequences and tight gas enrichment stages. We obtained insight into the relationship between fracture evolution and hydrocarbon charging, particularly the effect of the apertures and intensity of natural fractures on tight gas production. We reveal that the bedding fractures are short horizontal migration channels of tight gas. The tectonic fractures with middle, high and nearly vertical angles are beneficial to tight gas vertical migration. The apertures of fractures are controlled by the direction of maximum principal stress and fracture angle. The initial gas production of the vertical wells presents a positive correlation with the fracture abundance, and the intensity and aperture of fractures are the fundamental factors that determine the tight gas production. With these findings, this study is expected to guide the future exploration and development of tight gas with similar geological backgrounds.

中文翻译：

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致密含气砂岩中的天然裂缝——以川西新场气田上三叠统须家河组为例

上三叠统须家河组是典型的致密气藏，天然裂缝决定了致密气的运聚和生产能力。在本研究中，我们重点研究了天然裂缝对致密气运移和生产的影响。我们根据成像测井解释和岩心描述，明确了裂缝的特征和属性（即倾角、孔径、充填度和横切关系）。考虑了以往对电子自旋共振、碳氧同位素、流体包裹体均质化温度分析和盆地模拟的研究。本研究还分析了裂缝层序、裂缝充填物来源、成岩层序和致密气富集阶段。我们深入了解了裂缝演化与油气充注之间的关系，特别是天然裂缝的孔径和强度对致密气产量的影响。我们揭示了层理裂缝是致密气的短水平运移通道。中、高、近垂角构造裂缝有利于致密气垂向运移。裂缝孔径受最大主应力方向和裂缝角度控制。直井初始产气量与裂缝丰度呈正相关，裂缝强度和裂缝孔径是决定致密气产量的基本因素。有了这些发现，