Geological Model Of The Low Permeability Reservoir Based On The Reservoir Architecture

The reservoir of the first sub-member of eighth member of Chang formation in Zhen 218 block in Zhenbei Oilfield had the typical characteristics of low permeability,and serious heterogeneity.The distribution regularities and the internal configuration of sand body was not studied clearly,and the 3D geological model was not established either,which restricted the further exploitation of the reservoir.To tackle with these problems,taking Zhen 218 block as example,I studied the internal architecture of the reservoir in detail by using the method of analytic hierarchy process.Calculating the physical parameters of the low permeability reservoir in different unit of different architecture elements,I established the 3D architecture model and 3D reservoir attribute model of the first sub-member of eighth member of Chang formation in Zhen 218 block.Finally,I used different methods to test and verified the model finally in the study area in this paper.The main conclusions and achievements are as follows:(1)The reservoir of the first sub-member of eighth member Yanchang Formation in Zhen 218 block belongs to braided-river delta front sedimentary environment.The distribution of sand body was along the South West-North East direction with wide distribution and large thickness,displaying multiple channel sand body overlaying vertically which is favourable for oil and gas reservoir.(2)The internal architecture is limited by 5th-level interface of the first sub-member of eighth member of Yanchang Formation in Zhen block 218.Among them,the 3rd-5th level architecture interface controlled the characteristics of the internal level,level 3 architecture interface is not continuous,level 4 architecture interface was more stable and also a certain continuity,Level 5 architecture interface basic area-wide distribution.According to the deposition causes,the main types of the interface of the study area was divided into muddy surface,physical surface and calcareous surface and the identification standard of different surfaces was established.(3)The internal level features of research Area was clarified and three ways to identify the river boundaries were proposed.Furthermore,we established the empirical formulas between sand thickness and channel widths,further divided the formation stages of the river into 5 periods,identified five types of sand body contacts of spaces and summarized the architecture mode of Braided-River Delta Front underwater distributary channel.(4)Clay content model,Porosity model,permeability model and oil saturation model of the low permeability reservoir of Zhen218 block were established.The physical parameters of low permeability reservoir were calculated.After analyzing and verifying the results of logging interpretation,core analysis laboratory error was significantly reduced,producing fluid strength and permeability parameters have good match,the rate of oil production was close to 90%.The logging interpretation result more reasonable.(5)3D geologic model(Structural model,architecture model,property model of the low permeability reservoir based on the reservoir architecture)of research area were established,and verified that the models were correct.Taking advantage of testing the statistical parameters of the model and inputting parameter probability distribution of unity,I compared mode of architecture control and non-configuration and accomplished the reservoir numerical simulation test which verified the correctness of the model.