EVIDENCES FOR DEPOSITS OF FLUVIAL FACIES IN SHANXI FORMATION IN NORTHEASTERN ORDOS BASIN

There is much disagreement over the sedimentary facies of the Permian Shanxi Formation, especially its second member, which is the main pay zone in the northeastern part of the Ordos Basin, leading to great variations of the interpreted sandbody distribution and sandstone correlation results for each sedimentary system, thus further increasing the difficulties of prediction of high quality sandbodies and exploration deployment. The sedimentary facies of the Shanxi Formation in this area is comprehensively studied based on previous understandings and in combination with the logging, seismic, core and outcrop data. The results show that fluvial outwash is a fundamental factor controlling the formation and distribution of the high quality reservoirs in the eastern Ordos Basin. A new sedimentary system concept of wetland-strong erosion-restricted channel incised valley fill is proposed and the corresponding sedimentary models and exploration directions are presented.