Diagenesis and reservoir quality of the second member of the Upper Triassic Xujiahe Formation tight gas sandstones in the Western Sichuan Depression, southwest China

2021 ◽  
Author(s):  
Bo Pan ◽  
Hongde Chen ◽  
Liangbiao Lin ◽  
Yu Yu ◽  
Dong Wu ◽  
...  
Keyword(s):  
Southwest China ◽  
Upper Triassic ◽  
Reservoir Quality ◽  
Tight Gas ◽  
Xujiahe Formation ◽  
Western Sichuan ◽  
Tight Gas Sandstones ◽  
Western Sichuan Depression

Natural fractures in tight gas sandstones: a case study of the Upper Triassic Xujiahe Formation in Xinchang gas field, Western Sichuan Basin, China

2021 ◽  
pp. 1-18
Author(s):  
Yunzhao Zhang ◽  
Lianbo Zeng ◽  
Wenya Lyu ◽  
Dongsheng Sun ◽  
Shuangquan Chen ◽  
...  
Keyword(s):  
Production Capacity ◽  
Gas Production ◽  
Upper Triassic ◽  
Tight Gas ◽  
Natural Fractures ◽  
Carbon And Oxygen Isotopes ◽  
Gas Field ◽  
Xujiahe Formation ◽  
Western Sichuan ◽  
Tight Gas Reservoir

Abstract 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.

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