Discovery and significance of sublacustrine slump turbidite fans in Chang 6 oil-bearing formation of Baibao region in Ordos Basin,China

Chang 6 of the Upper Triassic is one of the most important exploration target zones in the Baibao region,Ordos Basin.The research on its sedimentary facies types and its control over the sandstone distribution and reservoir and other exploitation geology questions is paid more attention.On basis of the analysis for cores and well-logging,the authors have thoroughly studied the sedimentary facies types and characters of Chang 6 oil-bearing formation of the Baibao region with casting thin sections,SEM,trace elements and porosity and permeability analysis and a great deal of indoor testing data.The authors propose that the sedimentary facies type of Chang 6 oil-bearing formation of the Baibao region is a sublacustrine slump turbidite fan for the first time, and lithology is lower componential and textural maturities microfine feldspar sandstone primarily,with graded bedding,fluidified convolute bedding,slipping-cut and deformational structures,minitype syngenetic faults,flute cast,groove cast,load cast and other turbidite sedimentary facies signatures.Based on the analyses of turbidite fan lithofacies assciations,deposition sequence and plane evolution characteristics foundation,with regional geology background,the authors discuss the genetic mechanism of the sublacustrine slump turbidite fan,set up relevant sedimentary models,and analyze its significance in developing the oil reservoir in Chang 6 finally.