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.