Abstract:

Abstract: Turbidite in the third member of Shahejie Formation in Linnan subsag features in small,size,large number and wide distribution.It is hard to fully predict turbidites,because the sandbodies with ambiguous seismic features could be easily missed in reservoir prediction when taking sand group as unit.Based on the principles of isochronism in sequence and sand group and diachronism in sedimentary isochronfacies,this paper establishes the recognition modes of lithofacies with ternary information including geologic facies,well log facies and seismic facies.By studying the structure,thickness and seismic attribute of the reservoir based on the unit of sequence,lithofacies and sandgroups individually,a threestep method is developed for the prediction of the turbidite reservoir in the unit of lithofacies: defining palaeotopography according to thirdorder sequence,determining plays according to lithofacies,and delineating reservoir distribution according to sand groups.The method has been successfully applied in Lunnan sag: four kinds of contact models between the delta front and prodelta subfacies were established,i.e.distal sandbarmudstone,distal sandbarturbidite,mouth barmudstone,and mouth barturbidite.The shape of multiple prodelta subfacies is defined,and the favorable turbidite reservoirs are predicted,laying a reliable basis for turbidite evaluation and exploration deployment in Linnan subsag.