Reservoir Architecture Characteristics Of Alluvial Fan Of Guantao Formation,in Du 84 Fault Block,Liaohe Depression

Alluvial fan reservoir is more or less found in the Meso-Cenozoic Basins of China,which has important significance to oil and gas development.Taking the Guantao Formation of the Neogene in Du 84,Shuguang Oilfield,Liaohe Depression as a case,under the condition of dense well pattern,this paper mainly deals with the hierarchy of internal architecture and the reservoir architecture characteristics of alluvial fan.By using the information of cores and logging data and the method of scale analysis,the architectural surfaces and elements are precisely anatomized.To further demonstrate its depositional complexity,four orders of architectural surfaces and two orders of architectural elements are divided in the inner fan and middle fan.The sixth bounding surface is equivalent to boundaries of individual alluvial fans.The fifth bounding surface is the boundary of compound sand body.The mud structure surfaces and the pebbly sandstones between two stages of channel sand bodies are the two types of the fourth surfaces.The muddy intercalation in the single channel are the third surfaces.Three kinds of the fifth architectural elements are divided into the Inner fan,which are main trench,sheet-flood belt and overbank belt.The debris flow deposits are developed in the main trench.In the sheet-flood belt,sand-gravel deposits are developed.In the overbank belt,fine deposits are developed.The main trench,braided-stream belt and overbank belt are the three kinds of the fifth architectural elements in the middle fan.In the main trench,the debris flow deposits are developed.Braided channels are developed in the braided-stream belt.The fine deposits are developed in the overbank belt.On the basis of the establishment of the hierarchy of architecture surfaces and elements,further analysis is developed in the Braided channel sand bodies.Following four aspects are involved.Firstly,five kinds of electrofacies are summed up,which are middle-high amplitude cylinder shape,middle-high amplitude serrated cylinder shape,middle amplitude thin cylinder shape,funnel shape and funnel-cylinder shape combination.Electrofacies show some differences and regularity in different parts of the river.Secondly,the sand bodies' contact style is summarized,the vertical style of which is divided into vertical superimposition,lateral overly,horizontal overlap and isolated distribution,the plane distribution pattern of which is divided into isolated bands and intersect bands.Thirdly,four marks of single channel sand body can be identified,which are inter-channel sediments,the different distance between sand body and top layer of adjacent wells,thick-thin-thick sand bodies association and characteristic of logging curves.Fourthly,the single channel scale is determined.Through drawing the sand bodies of the cross section,calculate out the width and the thickness of the clear boundary of sand bodies,and fit formulas of the width and thickness of single channel.Based on above research,facies models and property models are established.Facies models are applied by the method of deterministic simulation and sequential indicator simulation with facies contraints.Property models are applied by the method of sequential guassian simulation with facies constraints.It realize the change from qualitative to semi-quantitative,quantitative analysis.