Study On The Characteristics Of Tight Reservoir Of Qingshankou Formation In The Cretaceous Of Changling Depression,Songliao Basin

Daqingzhijing oilfield is located in Daqingzhijing village,Qianan County,Jilin Province,at the middle of Changling sag in the Central Depression of the southern Songliao Basin.The overall structure is a north-northeast wards gentle syncline,which is flat at the core of the syncline.The target layer of this paper is the first member of Qingshankou formation,whose sedimentary environment is delta front with fine sediments,mainly siltstone.When Qing 1 member was deposited,the environment was reductive under water environment with large scale of dark mudstone,which is favorable for oil generation.The physical properties of oil layer in the study area vary,with an average porosity of 12.8% and permeability of 3×10-3?m2.However,the severe reservoir hetreogeneity leads to poor understanding of fluid distribution rule,results in the integrated water cut reaching 86.5%.Besides,the effect of fracture and low permeability enlarges the development difficulty.Songliao Basin is facing a major strategic adjustment in the development field.Due to insufficient reserve resources,it is urgent to discover new resources.The oil and gas shows in tight reservoirs of Qingshankou formation,Songliao Basin are active,but it is subject to the theoretical and engineering factors and no major breakthrough has been made.Innovative research ideas and technical means are needed to release the potential of such resources.Conventional reservoir characterization technology has been unable to meet the research of tight reservoir characteristics,which requires comprehensive consideration of many factors and the formation of specific tight reservoir research methods.Take Hei 60 block in Daqingzijing oilfield as the study area and first member of Qingshankou formation as the target layer.On the basis of fine layer correlation and sedimentary characteristics research,with the integrated use of core,well logging and dynamic data,oil layer potentials in tight reservoir of Qing 1member are predicted,and the plane distribution rules of tight reservoir in the study area are studied.Through the study of the distribution of the single channel and the direction of artificial fracture,five kinds of combination models are summarized.Combined with the dynamic analysis of production and injection wells,the impact scope of each model under the rhombus nine point well patterns is studied,and the distribution of remaining oil in tight reservoir is summarized.Finally,four property relations in tight reservoir are studied and the oil layers in tight reservoir are identified,and the tight reservoir classification standard is set to guide further optimization of “sweet points”.