1. Department of Reservoir Evaluation，Changqing Oilfield Company，PetroChina，Xi'an 710018，China; 2. Exploration and Development Research Institute of Changqing Oilfield Company，PetroChina，Xi'an 710018，China; 3. National Engineering Laboratory for Exploration and Development of Low- Permeability Oil ＆ Gas Fields，Xi'an 710018，China

The deposition types of Chang 6 Member of the Yanchang Formation in Heshui area of Ordos Ba- sin，were firstly identified by core and outcrop observations，and then the sandbody structures were classified ac- cording to the combination of deposition types． Furthermore，the distributions of sandbody structure were revealed by logging responses，and the reasons for the plane differences of sandbody structures were synthetically analyzed． The results show that the main deposition type of Chang 6 Member in Heshui area was deep- water gravity flow depo- sition，which can be further divided into sandy debris flow deposition and turbidity current deposition． These two types of gravity flow depositions superimposed vertically，leading to widespread and thick sandbodies，which can be classified as superimposition of multi- stage sandy debris flow deposition，superimposition of sandy debris flow depo- sition and turbidity current deposition，and superimposition of multi- stage turbidity current deposition according to the differences in storage ability and oil enrichment． The distributive difference of sandbody structure effected by the bottom shape of lake basin，provenance，amount of debris and transformation of flow． Different types of sand- body have the belt distribution characteristics of vertical provenance axis，and the favorable sandbodies are in the northeastern and central parts of the Heshui area．