Similarities And Differences Of Sedimentary Sequences Of Alluvial Fans With Different Provenance Types And Their Geological Models

With the use of well-seismic data in China and the increasing maturity of stochastic modeling techniques for oil and gas reservoirs,how to use field profiles and other geological data with low cost and high accuracy to establish a field three-dimensional geological model is an innovative process of old technology and new applications.To this end,this paper selects the source alluvial fan of Aoyukou,Hebei,the source alluvial fan of Qiyiangleke line and the source alluvial fan of Subashi area in the southern margin of Tianshan Mountains,Xinjiang.Analyze and organize the indoor data,and on the basis of previous studies,summarize and analyze the deposition characteristics and microfacies distribution of alluvial fans of different provenance types,construct the fan filling pattern,and divide the deposition periods of different fans.Comparative analysis of different stochastic modeling methods,and finally the establishment of three-dimensional geological models of fan types of different provenances,to facilitate analysis and prediction of alluvial fan deposition evolution law.The main understanding and results of this study are as follows:1.According to the detailed description of the field profile,the sedimentary characteristics and development morphology of the alluvial fans of different provenances were identified.Among them,the point source alluvial fans identified 9 types of lithofacies in 3 major categories and divided 6 typical vertical sequences;The source alluvial fan has identified 4 major categories and 9 types of lithofacies,and divided 6 typical vertical sequences;the area source alluvial fan has identified 2 major categories and 9 types of lithofacies,and divided 5 typical vertical sequences.2.Compare the differences of depositional characteristics of alluvial fans from different sources.Among them,the point source alluvial fan has the largest change in particle size and impurity content,and large mudstone deposits appear at the fan end;the linear source alluvial fan has a large particle size,and no sandstone and mudstone facies are identified;the end of the area source alluvial fan There are a lot of sandstone facies in the distribution,and the bedding is obvious,and the abrupt interface between the facies is obvious.3.According to the comparative analysis of aerial photographs and satellite photographs of unmanned aerial vehicles,identify and divide the micro-phase distribution plan of alluvial fans of different sources.Combined with the field profile data,four main different filling types of the fan body were identified,namely mono-inclined type,steep first,then gentle type,steeply gentle type,and gently steep type.Based on this,different fan body deposition periods were divided,and the corresponding spatial geological model was established by combining horizontal and vertical profiles.4.Analyze and summarize several current mainstream stochastic modeling methods.The related theory,applicable conditions,advantages and disadvantages are briefly explained.And the mutual comparison analysis is carried out.The analysis shows that the sequential Gaussian simulation is suitable for the establishment of the physical property model,the sequential instruction simulation is suitable for the establishment of the lithology model,and the pointpoint simulation method is suitable for the establishment of the sedimentary microfacies model.5.According to the established alluvial fan models with different provenances,it can be seen that the alluvial fans with point provenances are developed more regularly,the direction of the channel development is single,and the content of impurities in the sedimentary areas with larger particle size is smaller;The point sources are connected laterally;the area source alluvial fan mostly has the phenomenon of oblique development or unilateral development and successive swings,and the particle size and the heterogeneous content do not correspond to the development.