Abstract:

In order to analyze the Mesozoic-Cenozoic tectonic transition and its significance for oil and gas distribution in the southern Jizhong depression， based on seismic data, geological structure characteristics, structure evolution and tectonic transfer of the southern Jizhong depression are analyzed, at the same time, the geological significance for petroleum exploration are discussed. The study shows the differences in the geological structure and evolution on the two sides of the Hengshui accommodation zone (HAZ). The northern part of the HAZ is characterized by a half-graben controlled by double detachment faults with opposite dips, and the southern part of the HAZ is characterized by a compound half-graben controlled by a single detachment fault with multiple faults. The Mesozoic-Cenozoic evolution of the southern Jizhong depression can be divided into the following five periods: basement evolution stage (Mesozoic), initial rift evolution stage (Ek-Es4), strong rift evolution stage (Es3-Es2), weak rift evolution stage (Es1-Ed) and post-rift evolution stage (after Ng). The southern Jizhong depression has experienced a tectonic transition from basement NNE structural systems to Cenozoic NE systems, and the change of the stress field during the Mesozoic to Cenozoic is the dynamic reason for the formation of multi-directional complex structures. The Cenozoic transition affects the distribution of effective source rocks by affecting the migration of troughs, and influences reservoir sand distribution by controlling sand entry channels. The gradient change of displacement of main faults during structural transformation results in transverse anticline forming a favorable position indicating oil and gas enrichment. The transform structures formed by the tectonic transfer in different scales have a certain exploration potential.

Key words: Bohai Bay basin； Jizhong depression')">

Bohai Bay basin； Jizhong depression, fault activity, tectonic transition, structural evolution, hydrocarbon distribution