Sedimentary Characteristics of Glutenite and Its Favourable Accumulation Facies:A case study from T₁b, Mabei Slope, Junggar Basin

Key words: 
• Mabei slope /
• T₁b /
• heavy mineral /
• dip angle /
• ancient landform /
• fan dalta

Abstract: To clear the sedimentary characteristics of glutenite and the distribution of favourable accumulation facies, With the integrated study of core, logging, seismic and experimental analysis, this paper draw conclusions that the sedimentation in T₁b, Mabei Slope subordinate to fan delta deposition, including five sedimentary microfacies as follows:braided-stream channel in fan delta plain, sandy-debris flow in fan delta plain or fan delta front, nearshore underwater-distributary channel, offshore underwater-distributary channel, and estuary dam in fan delta front. There developed two mechanism named tractive current and gravity current, and mainly developed Xiazijie fan and Huangyangquan fan. Xiazijie fan is divided into three branch-fans named FN10, XIA72, MA7. FN10 branch-fan and MA7 branch-fan are mainly developed sandy-debris flow. XIA72 branch-fan locate in Mabei heave. The slow grooves developed in Mabei heave controlled the distribution of tractive current. The intensity of reservoir diagenesis(compaction and cementation) is closely related to deposition(matrix content and granularity). Matrix content and granularity are main controlling factor of accumulation property. Transportation mechanism and sedimentary microfacies controlled the distribution of favourable accumulation facies. Sandy-debris flow deposition is poor reservoir. The different sedimentary facies belt in tractive current have different accumulation property. Braided-stream channel in fan delta plain and offshore underwater-distributary channel are sub-poor reservoir. Nearshore underwater-distributary channel and estuary dam in fan delta front are the best reservoirs. High-quality reservoir are mainly located in nearshore underwater-distributary channel, and fan delta front.