Sedimentary System Of E₁f₃³ Member In Funing Formation Of Paleogene In Gaoyou Depression

Taking the E1f3~3 formation of Gaoyou depression in Subei Basin as the research object,the core data,logging data and a series of analysis and test data are comprehensively used to redefines the sedimentary system type and restores the paleo-environment including antiquity,palaeogeomorphology,paleo depth,ancient wave condition,ancient wind direction and ancient wind force.Based on the comprehensive sedimentary system types and the six paleo restoration results,the sedimentary model of the work area is established,which provides a new method for predicting the favorable sand bodies and guiding the exploration in the old areas.The main contributions are as follows:1.Based on single well sedimentary facies analysis,cross section comparison and contour map of percentage percent of plane sandstone,the delta front subfacies,shore shallow lake beach bar facies,nearshore subaqueous fan facies and a few storm sedimentary facies are coexisted in the research area.2.Restoration of sedimentary paleoenvironment in key strata of the study area:(1)Paleogene analysis,it is determined that there are two source systems in the Gaoyou depression,northern depression source from Jianhu uplift,the southern depression source from south of Jiangsu uplift;(2)Paleo-geomorphology restoration,the residual thickness method is mainly composed of thickness correction,compaction recovery,formation burial history and get the three dimensional map of paleo-geomorphology;(3)Paleo-bathymetric and ancient wave condition analysis,as the result that surf zone is located at about 9m and breaker zone is located at 15m.;(4)ancient wind analysis,the main wind direction of the study area is southerly wind,and the ancient wind speed is 11.49m/s-26.61m/s,corresponding to the 6-10 stage wind.3.In accordance with the formation mechanism of the beach-bar,the depositional model of the beach-bar in the E1f3~3 of the Gaoyou depression is established,including the normal wind wave beach-bar deposition mode,the storm flow beach-bar deposition model and the complex genesis beach-bar deposition model.4.There are three types of sedimentary system in the research area:the wave controlled delta and beach-bar system which located on the southern side of the Jianhu uplift in the northern Gaoyou depression;the nearshore subaqueous fan system which located on the northern side of the South of Jiangsu uplift in the southern Gaoyou depression and a storm depositional system in a semi deep lake.5.The location and scale of favorable sand bodies are predicted.It is believed that there are probably unexplored sand bodies near Sha 16 well in central Gaoyou sag,and a far shore dam with 6 m-11 m thick can be formed under the condition of6-10 stage wind,and the extension of the single dam is 3.8km-7km.