Main control factors on lake gravity-flow deposit sandbodies-a case study in Chang 7 of the Ordos basin

Lake gravity flow deposit sandbodies are highly potential for oil/gas exploration and exploitation. Based on in-field cross-section and core observations, well logging data, and theories of deep-water deposition, we systematically characterized the gravity flow deposits in Chang 7. The results show that 3 genetic types of gravity flow deposit sandbodies were formed in the study area: sandy clastic flow deposits, turbidity flow deposits, and slump deposits. Specifically, sandy clastic flow deposit sandbodies were distributed proximally, while turbidity flow deposits were distributed distally. Along the direction of source supply, the sandy clastic flow deposits gradually changed to turbidity flow deposits. The sandbodies were highly connective in the longitudinal direction, but poorly in the crosswise direction. Generally, the gravity flow sandbodies were spread in a strip-like way. The main control factors affecting the formation and evolution of gravity flow sandbodies include lake basin bed-form, lake level and flow intensity, mud-sand composition and concentrations, and multi-source confluence.