Architecture Characterization And Three-dimensional Modeling Combined With Well Logging And Seismic Data In Chang 7 Oil Group,Li 89 Block,Huanxian Area

Chang 7 Member of Triassic Yanchang Formation is one of the important oil-bearing intervals in the Ordos Basin.The semi-deep to deep lacustrine gravity-flow sedimentary system is developed in the Chang 7 member.The distribution of sandbodies in the Chang 7 reservoir is very complex,and the genetic type and architecture distribution of sandbodies are still unclear,which limits the process of the exploration and development of tight oil and shale oil.Therefore,it is urgent to carry out the research on the sedimentary architecture of lacustrine gravity-flow reservoirs to provide necessary geological basis for fine exploration and efficient development of complex reservoirs in similar oilfields.This thesis takes the tight sandstone,sublacustrine fan reservoir of the Chang 7Member in the Li89 Block,Huanxian Area,Ordos Basin as the research object.Guided by the theory of sedimentology,sequence stratigraphy and reservoir geology,this study is conducted by integrating the core,well logging and seismic data.Based on the establishment of fine isochronous stratigraphic framework,the types and characteristics of architecture units are determined,and the distribution of sandbodies is predicted by using the method of intelligent fusion combined with well logging and seismic data.Moreover,the geometric characteristics and spatial stacking patterns of single sandbody are clarified,and the semi-quantitative and quantitative architecture model of single sandbody is established.Finally,the three-dimensional architecture model of single sandbody is established to illustrate the spatial distribution characteristics of single sandbody.The research results are as follows:(1)The frequency-decomposed and fused seismic attributes are used to predict the distribution of sandbodies in the sand group,and the three-dimensional lithology model is established based on artificial intelligence inversion to predict the distribution of sandbodies in the small layer and the single layer.The sandbodies of the single layer are mainly distributed in fan or tongue shape,and isolated sandbodies exist locally.(2)The distribution pattern of reservoir architecture units of sublacustrine fan in the study area is determined.The lobe sandbodies are extensively developed.The single lobe is fan-shaped or tongue-shaped on the plane and is slightly narrower in the proximal region as well as slightly wider in the distal region,and the lobe in the profile shows the geometric shape of flat at the bottom and convex at the top.The channel is developed in the upper part of the lobe,and the channel in the profile shows the geometric shape of flat at the top and convex at the bottom.(3)The semi-quantitative and quantitative architecture model of single sandbody is established.The maximum thickness of a single sandbody ranges from 2.6 m to 8.5 m,and the maximum width is 770 m to 2600 m.There is a positive linear correlation between the maximum width and the maximum thickness,and the average width-thickness ratio is244 to 356.The vertical superposition patterns of single sandbody in the study area include the isolated,spaced and continuous superposition pattern,and the lateral superposition patterns of single sandbody includes the isolated and lateral overlap pattern.(4)The method of single sandbody architecture modeling controlled by the microstructural surface of sandbody is used to establish a three-dimensional single sandbody architecture model.The spatial distribution of single sandbody architecture varies significantly among different single layers,including the types of sandstone wrapped by mudstone,sandstone-mudstone interbedded and mudstone wrapped by sandstone.