Inclusion Characteristics of the Fracture-Cave Calcite of Ordovician Yingshan Formation and Its Indication to the Formation of Paleokarst Reservoir in the Northern Slope of Tarim Basin Center Area, China

• DOI: 10.3389/feart.2022.879297
• Publication Date: 2022-04-19T05:06:24Z
• Authors: Yong Dan; Junjie Ba; Bin Liang; Qingyu Zhang; Jingrui Li; Guoquan Nie
• Keywords: Temperature salinity diagrams

A karst fracture-cavity was developed in the Ordovician Yingshan Formation northern slope of Tarim Basin center area (Tazhong area); however, experienced multistage and diagenesis later period, reservoir heavily reformed, characterized by complex distribution. Based on testing inclusions fractures fracture-cave calcite, this study summarizes physical chemical characteristics Tazhong. The major were liquid gas–liquid phases, while minor ones hydrocarbon phases. salinity–homogenization temperature diagram, could be divided into seven types: low-temperature low-salinity (the lowest salinity 0.88%, which is lower than that present sea water; 49°C); high-salinity inclusions; medium-temperature medium-salinity high-temperature inclusions. development high or low salinity. In addition, near unconformity surface well-developed. higher-salinity far from also burial history analysis showed three stages karstification filling area: exposed Middle Caledonian, shallow Hercynian, Late Hercynian. By determining calcite associated with mud caves combined previous studies, Caledonian found to period eogenetic meteoric water seawater. This key factor formation reservoirs Tazhong area. large-scale growth Hercynian periods led further early reservoir, reduced space, enhanced heterogeneity.