Abstract:

Zhuangxi Buried-hill is one of the most tectonically complicated regions in Jiyang Depression. It experienced multiphase
tectonism with good prospects for oil and gas exploration and development. However, its tectonic evolution has not been studied in detail, impeding the exploration and development work. Here we study the tectonic evolution of Zhuangxi Buried-hill by the method of cross-section balancing on the basis of regional tectonic evolution analysis. Results indicate that Zhuangxi Buried-hill was controlled by the cratonic tectonic setting after the North China continental core formation in Archaean to Mesoproterozoic and was mainly carbonate-based deposition conditions in the early Paleozoic. Zhuangxi Buried-hill experienced three evolutionary stages: the Indosinian folding related uplift, the Yanshanian fault block uplifting, that the Himalayan tectonic uplifting and burial. Bedrock strata underwent two episodes of weak compressional tectonism in Indosinian and late Yanshanian. The present fold is a rolling anticline formed in Himalayan. Zhuangxi Buried-hill is a lower compression-arch fold Buried-hill. The reservoirs in the Zhuangxi Buried-hill are mainly composed of Cambrian-Ordovician carbonate rocks in lower Paleozoic, the tectonic evolution controlled distribution of reservoirs in the Zhuangxi Buried-hill. The reservoir type is dominated by fault karst zone and fracture, followed by the weathering crust karst belt, mainly formed within the fractured Buried-hill reservoirs. The oil and gas of Zhuangxi Buried-hill came from source rocks of the lower part of the third member of Paleogene Shahejie Formation, and then migrated through the Zhuangnan fault to Zhuangxi Buried-hill and formed reservoirs. There are two kinds of accumulation models in Zhuangxi Buried-hill: compression-arch-fold type and compression-tension-block type. The compression-arch-fold accumulation is mainly distributed in the western limb of the anticline. The
compression-tension-block accumulation is mainly distributed in the anticline axis region where the stress is most concentrated, and it is the main type of high-yield reservoirs.

Key words: Tectonic background, Formation mechanism, Tectonic evolution, Accumulation characteristics, Accumulation model;
Zhuangxi Buried-hill