石油实验地质2026，Vol.48Issue(3)：588-607,20.DOI:10.11781/sysydz2026030588
浅层海相页岩气储层孔—缝系统成因及其"甜窗"预测意义
Genesis of pore-fracture systems in shallow marine shale gas reservoirs and its significance for"sweet window"prediction:
摘要
Abstract
The shallow marine shale gas reservoirs in the Upper Ordovician Wufeng Formation and the Lower Silu-rian Longmaxi Formation of residual synclines in northern Guizhou have experienced episodic tectonic superim-posed reformation.As a result,reservoir-preserving matching and reservoir formation and gas accumulation mecha-nisms are complex,leading to significant differences in development efficiency among different sub-layers.There-fore,it is of great significance to investigate the differential characteristics of interconnected pore-fracture sys-tems in different shale sub-layers of various syncline units and gas-bearing intervals for better understanding the reservoir-forming mechanisms and optimizing reservoir targets.Taking the shallow marine shales from the Wufeng-Longmaxi formations in northern Guizhou as the research object,various methods were comprehensively applied including dynamic reconstruction of tectonic burial history and pressure evolution,whole rock X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM)imaging,image extraction using Image Pro Plus/Image J,high-pressure mercury intrusion,and directional spontaneous imbibition experiments.Besides,using key parameters such as the timing and amplitude of the last tectonic uplift and the average depressurization rate,the study validated the relatively superior tectonic preservation conditions of the gas-bearing unit in the Shixi syncline.On this basis,the preservation of organic matter pores and the genetic mechanism of interconnected pore-fracture systems in different sub-layers of the first member of the Wufeng-Longmaxi formations in the Shixi area were further elucidated.Specifically,in well SX1 of the Longmaxi Formation,organic matter pores were best developed in sub-layer ⑤,followed by sub-layers ③ and ④,and were least developed in sub-layers ①+②.Moreover,the proportion of rigid minerals-organic matter-clay composites in the microscopic field of view was rela-tively larger in sub-layers ⑤ and ③,followed by sub-layers ④ and ①+②.The spontaneous imbibition slopes parallel to beddings were 0.234 and 0.122 for sub-layers ⑤ and ③,respectively,higher than 0.090 and 0.053 for sub-layers ④ and ①+②.The average mercury withdrawal efficiency values of high-pressure mercury intru-sion were 37.047%and 31.912%for sub-layers ⑤ and ③,respectively,higher than 29.48%and 27.55%for sub-layers ④ and ①+②.The findings implied that the composites contributed significantly to organic matter pore preservation and pore-fracture system connectivity.Based on these findings,the study establishes a classification scheme for the genesis of microscopic pore-fracture systems in the shallow marine shale reservoirs from the Wufeng-Longmaxi formations in northern Guizhou and clarifies their reservoir-controlling mechanisms under the coupling constraints of dynamic and static gas accumulation elements.Three genetic models of pore-fracture systems were proposed,including pore preservation and fracture development with rigid minerals-organic matter-clay composites,relative pore preservation and fracture development with rigid minerals-organic matter-clay composites,and pore collapse type with the enrichment of rigid minerals parallel to shale beddings.关键词
有机质孔/刚性矿物—有机质—黏土微观复合体/甜窗/海相页岩气/五峰组—龙马溪组Key words
organic pore/rigid minerals-organic matter-clay micro-composites/sweet window/marine shale gas/Wufeng-Longmaxi formations分类
能源科技引用本文复制引用
杨威,缪克,侯昊东,姜振学,林瑞钦,赵福平,杜威,石富伦,丁谋..浅层海相页岩气储层孔—缝系统成因及其"甜窗"预测意义[J].石油实验地质,2026,48(3):588-607,20.基金项目
国家自然科学基金项目(42172140)、页岩油气富集机理与高效开发全国重点实验室开放基金课题重点项目(33550000-24-ZC0699-0056)联合资助. （42172140）
