Experimental Simulation of Terrigenous Organic Matter Sedimentary Characteristics and Its Influencing Factors in Transitional Facies Delta Depositional System
[Objective]Owing to favorable hydrocarbon accumulation conditions,terrigenous marine source rocks are widely developed in the transitional facies delta sedimentary system,and terrigenous organic matter is the main source material.To investigate the sedimentary characteristics and influencing factors of terrigenous organic matter in the transitional deltaic sedimentary system,a simulation experiment of terrigenous organic matter deposition was con-ducted.[Methods]The dynamic quantitative characterization of terrigenous organic matter transport and deposition process under experimental conditions was realized using a carbon and sulfur analyzer to detect total organic carbon content with three-dimensional(3D)laser scanning technology.[Results](1)In the delta plain,terrigenous organic matter mainly accumulates locally in the overflow areas of river channels,abandoned river channels,and the flow surface behind sandbar.In the profile,the distribution of terrigenous organic matter is mainly lens,discontinuous,and interbedded type.In the delta front and fore delta,the organic matter is distributed in a sheet on the plane,and it is distributed in strips with large thickness in the profile.(2)The transport distance of terrigenous organic matter in the gentle slope delta system is relatively long.With the gradual increase of the sediment thickness of the delta,the influence of the initial slope of the delta on the transport distance of terrigenous organic matter has decreased.(3)Hydrodynamic strength and waves are important factors affecting the transport distance of organic matter.The weaker the hydrodynamic force,the more favorable the deposition of organic matter is.Waves prevent organic matter from moving forward and form multiple sand bars in the delta front.Organic matter is deposited in annular bands in the grooves between the bars.(4)In the transitional facies delta depositional system,the organic carbon content grad-ually increases from the delta plain to the delta front-pre-delta area and then decreases as the transport distance con-tinues to increase.[Conclusion]The enrichment sites and influencing factors of terrigenous organic matter has been deeply established,and the sedimentary model of terrigenous organic matter in the flume experiment model provides an important reference for oil and gas exploration and development in the transitional facies delta depositional system.
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