A Study On Reservoir Controled By Synthetic And Antithetic Faults In Qinan Slope Area Of Bohai Bay Basin

Bohai Bay Basin has experienced multiphase tectonic movements in paleogene,makes the fracture development generally,according to the relationship between the fault and dip direction can be divided into synthetic fault and antithetic fault,and exploration practice shows that there are many differences in the distribution location,formation time and vertical distribution of hydrocarbon of traps controled by synthetic fault and antithetic fault.Therefore,in this paper,the Qinan slope area in the south of Qikou depression of Bohai Bay Basin was selected as the research target area,the types of fault traps in the study area were systematically sorted out,and the fault controlled by the synthetic fault and antithetic fault were selected for detailed anatomy.At present,it is generally accepted that the fault growth process can be divided into three stages: isolated fault stage,soft-linkage stage and hard-linkage stage,the process of the fault segmentation growth directly affects the development of fault trap location and distribution,combining previous knowledge of fault trap,think that the gengetic mechanism of the synthetic fault trap is the difference of both sides of the fault activity and the function of the fault segmentation growth connection,while the antithetic fault trap is due to the reverse fault block tilted up function.Using fault displacement-distance curve and seismic profile along fault strike can quantitatively identify the location of fault trap development.Based on these two quantitative identification methods and theoretical analysis,it is clear that synthetic fault trap development is at the growing point of segment of the upper wall of the fault,while antithetic fault development is at the footwall of the fault.The formation and evolution of synthetic fault traps and antithetic fault traps were restored by means of maximum throw subtraction method,and it is clear that synthetic fault traps can only form after the fault enters the "hard-linkage stage" period,and antithetic fault-bound traps can form in the early stage of fault activity.Through the fluid inclusions homogenization temperature,and in combination with thermal evolution,sedimentary burial history and hydrocarbon generation history to determine that there are two phase of hydrocarbon filling,the first phase is the late period of Dongying Formation,the second phase is Guantao formation served up to now,the second phase of the hydrocarbon filling is the main reservoiring stage,use throw backstrip method to analysis the relationship between formation time of the fault trap and reservoiring stage to evaluate the time availability of fault-bound traps.Based on the analysis of two petroleum system controled by middle 1 member of Shahejie Formation and 2 member of Dongying Formation cap rock,divided into three types of vertical hydrocarbon distribution,determine that there are differences in vertical hydrocarbon distribution between synthetic fault and antithetic fault,synthetic faults can not only control the accumulation of hydrocarbon in multiple petroleum systems,but also in one petroleum system,antithetic faults often control the accumulation of hydrocarbon in one petroleum system,and analyze the genetic mechanism of the difference.Using shale smear factor and quantitative fluorescence technique to restore the vertical adjustment process of hydrocarbon,determine middle 1 member of Shahejie Formation and 2 member of Dongying Formation hydrocarbon vertical adjustment critical value,and the vertical seal of fracture was quantitatively evaluated,which provides theoretical basis for hydrocarbon exploration and development.