The Development Characteristics Of Structures Inversion In Jiyang Depression And Its Relationship With The Evolution Of Superimposed Basin

Inversion structure research is an important component of the petroliferous basin analysis. The structures inversion of Jiyang Depression and those formed inversion structures during the basin inversion were studied. Firstly based on three-dimensional seismic data,drilling and logging data, the inversion structures have been exactly identified and geometric features of inversion tectonics have been analyzed in Jiyang Depression. By comprehensive analysis of the unconformities characteristics, apatite fission track and fluid inclusions, the time of structures inversion in Jiyang Depression were made clear. The kinematic characteristics of structures inversion were quantitatively and dynamically analyzed by using the methods of balanced crossed section, fault activity velocity, inversion intensity coefficient. Spatial distribution of different-stage inversion structures was found out. Combined with the basin evolution and regional geological background, the Formation mechanism and effects on basin superposition of structure inversion in Jiyang Depression were probed. Based on the above study, the structure inversion controlling to hydrocarbon accumulation was studied by analyzing typical the oil and gas reservoirs related to structure inversion. The result show that it developed T3-K1 stage negative inversion, K2 and the end of Ed stage positive inversion during basin transitional stage and the end of Es4 stage positive inversion during interval stage of basin episodic evolution from Mesozoic to now. Structures inversion shows lateral compression-to-extension transformation, vertical uplift-to-subsidence transformation, normal-to-reverse faults transformation and the formation of inversion structures. The lateral and vertical structure inversion has universality and the inversion intensity shows that T3-K1 stage negative inversion is the strongest, K2 and the end of Ed stage inversion are in the second place, and the end of Es4 stage is the weakest. Basin structures inversion generates positive inversion structures and negative inversion structures, which can be subdivided into fault type negative structure, fold type positive structure, inherited propagation type positive structure and newborn thrust fault type positive structure and totally show nine types manifestation. The T3-K1 stage negative inversion shows mainly fault type and experienced from reverse to normal transformation of NW-trending faults. The negative inversion structures well develop in Jiyang Depression and inversion intensity lowers from north east to south west. The K2 stage positive inversion generates NNE-trending thrust faults in the northeast area and shows newborn thrust fault type positive structure. The end of Es4 stage positive inversion only produces a few of fold type positive structures and inversion intensity is weaker. The end of Ed stage positive inversion shows from normal to reverse transformation of boundary faults, which forms inherited propagation type positive structures and inversion intensity of the east area is stronger than west area. The interaction between the plates movement mode, development of deep faults, the formation of surrounding mountains and deep geodynamic setting result in structure inversion in Jiyang Depression. The development of inversion structure has selective. The development degree, inversion intensity and manifestation of inversion structures are related to direction, source and strength-weakness of superimposed extensional and compressional stress field of different stages and the occurrence of pre-existent faults system. Structure inversion affects basin pattern and vertical superposition. The structure inversion during basin transitional stage made the basin with different properties coherently superimposed. But the structure inversion during interval stage of basin episodic evolution only made the partial depocenter migrated. The basin structure inversion delayed secondary hydrocarbon generation of deeply buried source rocks, optimized source-reservoir-cap vertical assemblages and controlled hydrocarbon migration. It was favorable to form compressed anticline reservoir, unconformity reservoir and Buried hill reservoir in extensional faulted depression basin...