Characteristics and Genesis of Thick Sandbody in the Centre of Lake Basin in Ordos Basin——By Taking the 6th Member of Yanchang Formation in Huaqing Area for Example

In recent years,petroleum exploration has achieved fruitful results in the lake basin center of Ordos Basin.Only in the Huaqing Area,several hundred million tons of proved reserves were discovered in Chang 6 Reservoir.According to a large number of drilling core and well logging data,a large area of deep-water gravity flow sediment was developed,sandstone types included slump,sandy debris flow and turbidite rocks,in which the sandy debris flow sandstone was the thickest with best oil-bearing property.Sandbodies with different geneses were vertically stacked composed laterally and stable and large thickness of sandboby was created.Under the background of the lake basin evolution in Yanchang Formation,the stable distribution and formation of thick sandbody is controlled by the deep-water slope belt in the centre of Ordos Basin.