摘要
Based on core data,rock mineral and grain size analysis data,logging and drilling data,the main facies of thick sandstone of three oil-member in study area is braided river.The mudstone and sandstone interbeded in thick sandstone of oil-member are deposited in shore-shallow lacustrine,semi-deep lake to deep lake and delta.Based on seismic data and logging data and drilling data,sublacustrine fan and canyon can be identified in middle oil-member in southern study area.Through the study of facies evolution,braided river sandstone is present during lower lake level,and dark mudstone and sandstone are present in shore-shallow lacustrine,semi-deep lake to deep lake and delta during rising of lake level.Four lake level changes can be identified in Triassic System in study,which form four sets association of thick sandstone and mudstone(including Ketuer Formation).