Sedimentary characteristics and development pattern of turbidity event of Chang 6 and Chang 7 oil reservoirs in the southern Ordos Basin

The turbidite system was mainly developed in the half-deep lake to deep lake in Chang 6 and Chang 7 oil reservoirs of Yanchang Formation in the southwestern Ordos Basin.The system generated the typical reservoirs in this area and is important domain for oil-gas exploration.The provenance analysis of turbidite indicated that the deposits of turbidite had mainly originated from the west,south and south-west parts of Ordos Basin.According to the sedimentary characteristics,the turbidite could be divided into far-provenance,near-provenance,and thick-layer,thin-layer and micro-bedding turbidites.The turbidite of Yanchang Formation in Ordos Basin has the typical turbidite characteristics of low-density flow in lacustrine facies and origin of reduction environment and the collapse of braided river delta front in the south and west parts of the basin.The developing mode of turbidite in this area was established.