The Structure,sand Distribution Characteristics And Prediction Of Favorable Areas In The Second Member Of Nantun Formation In South Wuerxun Sub-sag Of Wuerxun Depression In Hailar Basin

By using comprehensive research method of oil and gas geology,combining with previous research results,this paper interprets the structural accurately and predicts seismic reservoir of the second member of Nantun formation in South Wuerxun sub-sag of Wuerxun depression in Hailar Basin,Combining with the research results of sedimentary facies,Reservoirs the reservoir distribution in target area.By analyzing the conditions and the distribution characteristics of oil and gas accumulation,confirm the pattern of oil and gas accumulation in the main target layer in this area,then predicts favorable traps.Research shows that,South Wuerxun sub-sag of Wuerxun depression is a complex fault block oilfield,lots of fault,high density,small fault block,controlled by complex fault system,fault nose and fault block traps are developed in this area,and traps are controlled by the fault or formed by fault covered,the distribution of traps has the characteristics of large scale and distribution in rows;the core and well logging data shows that,the second member of Nantun formation mainly developed the sedimentary system of braided river delta facies,turbidite fan and deep lake and semi deep lake,in the early the second member of Nantun formation,the whole area was influenced differently by the source of sediments came from east,the sandstone bodies in southeast extended narrowly,the sandstone bodies in northwest extended widely.In the late the second member of Nantun formation,the whole area was influenced by the source of sediments came from northwest,northeast,southeast and east,the sandstone bodies between wells change extremely,the sandstone bodies overlay on each other,it is difficult to determine the regular pattern of distribution of sandstone bodies.Based on the results of previous research,the source rocks of the second member of Nantun formation are widely distributed,the dark mudstone developed in the first member of Nantun formation is the best,and the distribution of source rock matched with distribution of sandstone bodies well,the reservoir distributed in circularity around the oil-generating sag,the oil and gas migrated in the vertical direction to the slope zone and steep slope zone around,great effected by faults,lithologic reservoirs,structural-lithologic reservoirs,structural reservoirs are developed.Wunan area can be divided into four oil and gas migration and accumulation unit,Wudong slope is the most favorable for oil and gas migration and accumulation unit.Based on the above research,the most likely area of oil and gas accumulation in favorable well area of thesecond member of Nantun formation in South Wuerxun sub-sag of Wuerxun depression is predicted,three zones have been discovered and fifteen traps have been put into effect.It can be used as a guide and reference for the further exploration and development in the second member of Nantun formation in South Wuerxun sub-sag of Wuerxun depression.