Controlling sand principle of source-sink coupling in time and space in continental rift basins: basic idea, conceptual systems and controlling sand models

As a study case in Bohai water,an idea from "source" to "sink" was firstly attempted to be applied to the sedimentary system in rifted lake basins,and it was considered that the entire dynamic process from sediment erosion,transportation to accumulation should be seen as a complete sourcesink system to discuss the sand enrichment mechanism.A sand enrichment area often corresponds to a complete time-space coupling system of sourcesink in any complex continental rift basin,and a time-space coupling system of source-sink generally includes three sub-systems,namely effective provenance sub-system,effective accumulation sub-system and base-level conversion sub-system.The effective provenance sub-system can be divided into the explicit and implicit types,and the implicit type can be again divided into the time-implicit provenance system and space-implicit provenance system.It is of great significance in reservoir prediction to identify the implicit provenance systems in a continental rift basin.The effective accumulation sub-system is composed of some sediment transport channels,slope break zones and detritus accommodation space.The base-level conversion sub-system will mainly control the period of sandbody development in a sequence.The complex tectonic evolution in Bohai water has resulted 7 controlling sand models of source-sink coupling in time and space,including the corner-style source-sink system along basin margin faults,the strike-slope-style source-sink system along basin margin faults,the opposite-consumption-style source-sink system along basin margin faults,the valley-style sourcesink system along basin margin faults,the strikeslip fault source-sink system along basin margin,the valley-style source-sink system along uplift axes and the valley-style source-sink system on ramps.The exploration results have indicated that the controlling sand idea of source-sink coupling in time and space can significantly improve the success rate of Paleogene reservoir prediction in Bohai water,making great contributions to promoting the Paleogene exploration.This idea will also be an important reference for sedimentary system analysis and reservoir prediction in other similar basins.