川西坳陷合兴场气田须家河组二段（以下简称须二段）砂岩为超低孔、超低渗致密砂岩储层，裂缝较为发育且类型多样，裂缝的发育程度对天然气的运移、成藏及产能具有重要影响。为了优化研究区的勘探开发，综合利用岩心观察、薄片观察、成像测井分析、裂缝充填物包裹体分析等，对须二段裂缝发育特征及控制因素开展了研究。研究区的裂缝按照成因可分为构造裂缝、成岩裂缝和异常高压裂缝3大类，对应的发育时期分别为印支晚期、燕山中晚期和喜马拉雅期。构造裂缝具有裂缝延伸长、宽度大、充填程度较低的特征；成岩裂缝以层理缝为主，发育少量缝合线；异常高压裂缝发育较少，与生烃增压有关。在此基础上进一步明确了裂缝发育主控因素，构造裂缝的发育程度主要受构造变形、断裂、岩层厚度和相变等多方面因素的影响；成岩缝的发育程度主要受岩石相和岩层厚度的影响；异常高压缝发育程度主要受生烃增压的影响。结合研究区须二段构造样式和岩性组合，建立了须二段裂缝成因模式，研究区须二段的裂缝发育区在构造转折端、南北向断层附近的单层砂岩厚度适中带（砂泥互层、厚砂薄泥型）、南北向岩相变化带、异常压力发育区。

The Hexingchang gas field of the western Sichuan Depression is an ultra-low porosity and ultra-low permeability tight sandstone reservoir, with well-developed and diverse types of fractures. The degree of fracture development plays a pivotal role in influencing on the migration, reservoir formation, and productivity of natural gas. In order to guide the exploration and development of the area, a comprehensive study was conducted to examine the development characteristics and underlying factors controlling fractures within the second member of Xujiahe Formation. This investigation drew upon a range of analytical techniques, including core observation, thin section analysis, imaging logging, and the examination of fracture filling inclusions. The fractures in the research area can be divided into three categories based on their genesis: structural fractures, diagenetic fractures, and abnormally high pressure fractures. There are three stages of development of structural fractures, corresponding to the late Indosinian period, mid late Yanshan period, and Himalayan period. Structural fractures have the characteristics of long extension, large width, and low filling degree of fractures; The diagenetic fractures are mainly bedding fractures, with a small amount of sutures developed; The development of abnormally high pressure fractures is relatively rare, which is related to hydrocarbon generation and pressurization. Building upon this foundation, the main controlling factors for the development of fractures were further clarified. The degree of structural fracture development is primarily influenced by a multitude of factors, including structural deformation, fractures, rock facies, rock layer thickness, and phase transformation; The development degree of diagenetic fractures is primarily influenced by rock facies and rock layer thickness; The development degree of abnormally high pressure fractures is chiefly influenced by hydrocarbon generation and pressurization. Based on the structural style and lithological combination of the second member of Xujiahe Formation in the research area, a fracture genesis model has been established. The fracture development area of the second member of Xujiahe Formation in the research area is located at the structural turning point, near the north-south trending fault, with a moderate thickness of single layer sandstone（sand mud interbedding, thick sand thin mud type）, a north-south trending lithofacies change zone, and an abnormal pressure development area.