The Coarse-Grained Lacustrine Slope Apron Deposits in the Moliqing Area,Yitong Basin,Northeast China

Overlapping gravity accumulation bodies were formed on the northwestern steep slope of the Shuangyang Formation in the Moliqing fault depression of northeast China.This study analyzed in detail the spatial distribution of the lithofacies and lithofacies associations of these accumulation bodies based on more than 600 m of core sections,and summarized 12 major types of lithofacies and three types of lithofacies associations：（1） the proximal zone consists of gravelly debris flows dominated by alluvial channel conglomerates;（2） the middle zone is dominated by various gravity flow deposits and traction flow deposits;and（3） the distal zone is dominated by mudstones with intercalations of sandy debris and turbidites.Combining with the grain size cumulative probability curves analysis,we determined the transformation of debris flows to sandy debris flows and to turbidity currents in the slope zone of the basin margin,and further proposed a lacustrine slope apron model that is characterized by（1） an inconstant multiple source（line source）,（2） an alternation of gravity flow deposits and traction flow deposits dominated by periodical changes in a source flood flow system,and（3） the transformation of sandy debris flow deposits into distal turbidity current deposits.This sedimentary model may be applicable to other fault depressions for predicting reservoir distribution.

Seismic sedimentology of conglomeratic sandbodies in lower third member of Shahejie Formation (Palaeogene) in Shengtuo area, East China

The sand-conglomerate fans are the major depositional systems in the lower third member of Shahejie Formation in Shengtuo area, which formed in the deep lacustrine environment characterized by steep slope gradient, near sources and intensive tectonic activity. This work was focused on the sedimentary feature of the glutenite segment to conduct the seismic sedimentology research. The near-shore subaqueous fans and its relative gravity channel and slump turbidite fan depositions were identified according to observation and description of cores combining with the numerous data of seismic and logging. Then, the depositional model was built depending on the analysis of palaeogeomorphology. The seismic attributes which are related to the hydrocarbon but relative independent were chosen to conduct the analysis, the reservoir area of the glutenite segment was found performing a distribution where the amplitude value is relatively higher, and finally the RMS amplitude attribute was chosen to conduct the attribute predicting. At the same time, the horizontal distribution of the sedimentary facies was analyzed qualitatively. At last, the sparse spike inversion method was used to conduct the acoustic impedance inversion, and the inversion result can distinguish glutenite reservoir which is greater than 5 m. This method quantitatively characterizes the distribution area of the favorable reservoir sand.