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四川盆地灯影组以一套碳酸盐岩沉积为主,优质储层发育普遍受岩溶作用影响。川北米仓山地区早古生代为一个范围相对稳定且露出水面的陆地,在桐湾期与川中古隆起具有很好的可对比性。通过重点剖面碳、氧同位素特征分析及镜下观察,对灯影组二段和灯影组四段(下文简称“灯二段”和“灯四段”)不整合岩溶特征进行了系统对比。灯二段储层表现为葡萄状白云岩发育顺层、穿层溶蚀洞缝;而灯四段则以砂糖状白云岩晶间孔、藻纹层白云岩针状溶孔和角砾间孔隙为主,与前者相比灯四段表现为更多类型且更为发育的储集空间。灯二段、灯四段不整合面附近碳、氧同位素值由底及顶有逐渐变低的趋势,且灯四段白云岩碳、氧同位素值比灯二段整体较低,在纵向分布上更为偏负。综合说明了桐湾二幕较桐湾一幕构造抬升更为强烈,灯四段较灯二段受表生岩溶剥蚀影响更深,反映了桐湾运动不整合对灯影组储层发育起着主要控制作用。
The Dengying Formation in Sichuan Basin is dominated by a set of carbonate sediments, and the development of high-quality reservoirs is generally affected by karstification. The Early Paleozoic in the Micangshan area of northern Sichuan is a land with a relatively stable range and surface water, and is quite comparable with the paleo-uplift of the middle Sichuan Basin. Through the analysis of the carbon and oxygen isotopes in the key sections and the microscopic observation, the unconformities of karst features in the second section of the Dengying Group and the fourth section of the Dengying Group (hereinafter referred to as “the second section of the lamp” and “the fourth section of the lamp”) were systematically studied Compared. The second member of Dengzhang Formation shows gravel-like dolomite developed along the bedding and dissolved cave seams; while the fourth member of Dengzhang Formation is composed of intergranular pores of dolomite in granulite, alveolar dolomitic acicular pores in algal layer and pores in breccia Lord, compared with the former four sections of light showed more types and more development of storage space. The carbon and oxygen isotopic values of carbon and oxygen near the unconformity surface of lamp 4 tend to decrease gradually from the bottom to the top, and the carbon and oxygen isotopic values of dolomite of the fourth member of the lamp are lower than those of the second lamp. In the longitudinal distribution More negative. The results show that the structure of Tongwan II curtain is more intense than that of Tongwan, and the influence of surface karstification and denudation on the second section of Lantern Section is more profound. It indicates that the unconformity of Tongwan plays a major role in controlling the development of the Dengying Formation. .