Evolution and depositional model of distributive fluvial system in narrow and shallow lacustrine basin -- Insights from flume experimental simulation

Key words: 
• distributive fluvial system /
• low accommodation /
• flume experimental simulation /
• sedimentary characteristics /
• upper Kaidu River basin

Abstract: [Objective]Distributive fluvial system (DFS) are widely developed in modern and ancient sedimentary strata and are important hydrocarbon reservoirs. Multiple DFS interacting with each other and evolving axial rivers may be developed in narrow, shallow, narrow lacustrine basin with low accommodation. [Methods]Reproduced the deposition process through flume simulation experiments, and used a high-precision 3D scanner with a self-developed program to visual analysis the deposition area in three dimensions, to clarify the stage-by-stage evolution characteristics of the DFS. [Results and Discussions]1) with the expansion of the DFS scale, the water flow on the surface of the DFS gradually aggregates, and the initial flow pattern is sheet flow, then evolves into unrestricted flow, and finally restricted flow; 2) as the basin can accommodate less space, the axial water flow in the basin gradually aggregates into axial river, and the axial river has a destructive effect on the two sides of the DFS and constantly breaks, and finally forms a Large-scale fluvial deposition; 3) When multiple DFS are developed in a narrow shallow lacustrine basin, the sedimentary sands are mainly concentrated at the DFS near the source and downstream of the axial river, and the longer the basin development time, the larger the scale of fluvial deposition. [Conclusions]This paper describes the developmental processes and sand body spreading patterns of multiple DFS and axial rivers developed in a narrow, shallow lacustrine basin with low accommodation and sufficient supply of material sources at the basin scale, which provides theoretical support for oil and gas exploration and the study of distributive fluvial system.