Research On Fault Systems And Reservoir-controlling Mechanisms Of South Of Wuerxun Depression

Development focus on Wudong slope of south of Wuerxun depression in Hailaer basin, the main purpose formations of oil and gas accumulation are N1, T21 and T22. The region of Wudong slope proved geological reserves is 4103×104t.As a major oil-producing region of south of Wuerxun depression, the evaluation intensity increases year after year. Although through the reservoir description and placing of wells optimization in the early-stage of the development, the success drilling rate remains low, the main reason of the low success drilling rate is complex geological conditions , mainly in the following two aspects: First, fault system is complex; Second, it is both fault and sand coupled with the complex relationship between oil and gas accumulation. Based on the above major contradictions of oil and gas accumulation, start from the fault system, analysis the relationship between fault and sand , and the oil and gas. Based on the tectonic setting of Wuerxun depression in the Hailar Basin, a combination of the latest theories and methods of structural geology, seismic stratigraphy and petroleum geology etc.,the use of seismic, well logging and development of dynamic data etc., we in depth analysis faults growth characteristics, the action law and evolution history, systematic analysis fault control reservoir mechanism and the oil-water distribution,and guide further development and deployment of south of Wuerxun depression.The characteristics of faults of south of Wuerxun depression are that the strike is main of NE and NS, the scale is primarily small, the density is big, the plane distribution is uneven, the fault combination typediverse. The main activity of faults are Tongbomiao formation,Nantun formation, Y2, Y3 and Qingyuangang formation. From the point of view that the process of formation and evolution of fault, there are four sets of fault systems: namely, an early extensional fault system, a medium-shear fault system, an early extensional and medium-shear fault system,an early extensional and mid-shear extensional and late reversal fault system. Analysis of different fault systems control effect on hydrocarbon migration and accumulation. Making use of lateral fault sealing to evaluate the trap risk. Summarizing the above analysis to establish a set of fault-controlled reservoir model, and further clarified the next target for exploration.