Fault Characteristics Of Wen'an Area And Hydrocarbon Migraation And Accumulation Controlling Mechanism In Jizhong Depression

The oil and gas exploration objects are becoming more and more complex and concealed,and the low order structure is the essence of oil finding,which is urgent to have a deep understanding of the low sequence fracture structure in the study area.The exploration results over the past few years show that faults have obvious control over the macro distribution of oil and gas in this area.A lot of research work has been done on its oil control from the characteristics of fracture combination,fracture evolution and fracture dense zone.However,no scholars have studied the mechanism of fault refraction,fault turning and stress distribution,fault surface morphology and its filling,and analyzed the oil control effect of low sequence fracture structure.In view of the above problems,the laws of fault control and the favorable zones predicted by predecessors need to be perfected with reliability and rationality.Therefore,this paper has carried out related research work,which is of great significance to the realization of increasing reserves and production in Wen'an.The following conclusions and knowledge are obtained in the comprehensive study:No.1.according to the characteristics of fracture development,the main types of faults in Wen'an area are syngenetic normal faults,epigenetic normal faults and strike slip faults.No.2.according to the distribution characteristics of the fracture plane,the turning point of the Wen'an area is generally visible,the arc and the folding lines are all developed,and the curved axis of the arc is obvious.The turning mechanism is in the same tectonic stress field.The physical and mechanical properties of lithology in different sedimentary periods are different.When the rock is broken,the shear angle is different and the single fracture also has the characteristics of bifurcation and expansion.When the fracture propagation is cut over the lithologic strata,the fracture occurrence occurs on the contact surface or the contact zone.No.3.The basis of seismic interpretation,the fault plane on the three section of hydrocarbon source rocks in Wen'an area is traced,and 4 kinds of plane morphology are obtained,such as convergence type,uniform type,divergent type and compound type.According to the steep and slow relation of the fault surface profile,the confluent,uniform and divergent sections in the plane are faced with the corresponding profiles.It is divided into 3 kinds:flatness type,upper convex type and lower concave type.No.4.The fault transition in Wen'an area controls the main direction of oil and gas.From the macroscopic distribution,oil and gas have the characteristics of selective migration along the concave side of the fault.The gravitational tensor on one side of the concave surface is larger than that on the side of the convex surface.The dominant fracture and its induced tensional crack and its micro fracture connection constitute the dominant migration channel,controlling the main flow and migration of the oil and gas,which makes the oil and gas accumulation in the middle and south of Wen'an area high,and the Northern Migration and accumulation degree is low.No.5.The morphology of the fault plane controls the migration and accumulation of oil and gas.Confluent and composite faults are the most favorable for oil and gas migration.It is the mainstream of oil and gas.In the middle and southern reservoirs of Wen'an,the formation of this combination is high and the distribution of oil and gas is good.The lateral sealing of fracture surface ratio controls the accumulation of oil and gas.The mud ratio in the first part of Wen'an area is the smallest and the oil and gas enrichment is the highest.