| Up to now，no large-scale oil or gas field group has been found in Leikoupo Formation of Middle Triassic in Sichuan Basin. The key problem is that the formation mechanism and distribution law of reservoirs are not well understood. Starting from the division and correlation of sequence stratigraphy, the stratigraphic distribution, sedimentation and reservoir characteristics of the Middle Triassic are systematically sorted out and analyzed by using the latest oil and gas exploration results and abundant basic data. The results show that: (1) the Middle Triassic Tianjingshan Formation (also known as “the Leikoupo Formation Member 5”) exists in the basin, which is one of the important favorable exploration strata in the Middle Triassic; (2) microbial carbonate rock is an important type of carbonate rock of Leikoupo Formation, which has the potential acting as large-scale effective reservoir; (3) dolomitization and karstification in paracontemporaneous period and karstification in supergene stage are the main controlling factors of reservoir pore forming in Leikoupo Formation, and the acid diagenetic environment in early burial period, dissolution and structural fractures in burial period are the key factors for pore maintenance, improvement and transformation; (4) the distribution zone of weathering crust karst around the paleouplift, and the distribution zone of the microbial rock and granular shoal reformed by paracontemporaneous and supergene karstification are favorable reservoir development zones. |
