Abstract: The turbidity channel sandstone is noted for its importance and complexity in deep-water oil and gas fields' exploration,evaluation and development.Due to its high heterogeneity and limitations in current study,various contradictions exist between the existing sedimentary models and observations in the practical application.Based on the information derived from core and outcrop observation,well logging,and high-frequency seismic tests,we categorized the internal facies of restricted incised channel system(Grade 3 configuration)and described their features.The turbidity facies model was summarized from the perspective of lithological cycles,and the lithologic 3D distribution was simulated by means of geologic modeling.The results show that, (1) four types of turbidite architecture elements could be identified from the seismic data,including lag deposits,slump debris flow deposits,superimposed channel sand deposits with high net-to-gross ratio(NTG)and natural levee channel deposits with low NTG,occurring from the bottom of the channel to the top.The turbidite channel sand bodies at every cycle are composed of these four architecture elements in varying proportions. (2) Grade 4-5 channels within the turbidite channel system(Grade 3 configuration)incise and fill repeatedly in the process of migration and swinging,which is the immediate reason for the high reservoir heterogeneity at present. (3) The 3D simulation of the turbidite channel architecture reconstructs the rhythmicity of lithological change and features of facies-controlled constraints,which can guide the design of development scenarios and optimization of well patterns.

Key words: turbidity channel, lithofacies, sedimentary architecture, geological modelling