| The Chang 7 tight reservoir in the Dongrengou Block,Dingbian Oilfield,which is in the early stage of exploration and development.The previous fundamental geological research work is weak,the reservoir characteristics and heterogeneity development discipline are not clearly understood,and the reservoir description needs further refinement.based on multi-logging series data,This article describes the core observations,using casting thin section,scanning electron microscopy,mercury intrusion,infiltration and other experimental analysis methods,combined with oilfield production data,We have a detailed study on the deposition of Chang 7 tight oil reservoirs Microfacies,sequence stratigraphy,petrological characteristics,diagenesis,pore structure,interlayer development,and reservoir heterogeneity were studied in detail,and reservoir reserves were recalculated.The petrel software was used to establish the reservoir structure model,phase model,porosity model,permeability model,and oil saturation model,which laid the foundation for the next exploration and development work,and achieved results as follows:1)According to the main sign layers characteristics of the region,Chang 7 is divided into two sub-segments,Chang71 and Chang 72,both of which have good inheritance,showing the characteristics of“three sources rocks and two reservoir”and the average thickness of Chang71 formations is 41.4m,subdivided into 2 sand groups,and the average thickness of Chang72formations is 74.9m,subdivided into 5 sand groups.It mainly develops the underwater distributary channel,the estuary dam,the far sand dam,and the subaqueous distributary bay sediments at the front of meandering river delta,and the lithologies mainly range from gray powder-fine sandstone,silty mudstone,dark gray mud shale,and gray matter to mudstones,sedimentary structures,various types of bedding,and accompanied by biological debris.2)The classification of Chang 7 reservoir rocks is mainly composed of crushed feldspathic sandstone,feldspathic lithic sandstones and feldspar sandstones.The pore types are mainly intergranular pores and dissolved pores.The average content of interstitial materials is 10.2%.In the development of the interstitial layer,the Chang72 layer internal dissection much more developer than Chang 71,and the arrival coefficient,variation coefficient,permeation level difference,and homogeneity coefficient of the Chang 7 in every sand group changes greatly,indicating that the reservoir has strong heterogeneity.The development of fractures are mainly concentrated on the top of Chang 71 and Chang 72,and other sand groups are relatively undeveloped.3)Analysis shows that the average porosity of core samples in Chang 7 is 5.14%and permeability is 0.53×10-3?m2.According to the logging parameters and test data,determine the minimum effective reservoir lower limit,porosity 5.0%,permeability0.13×10-3?m2,The oil saturation by closed fetch core method was 54.4%,mercury intrusion method was 53%,respectively.The effective oil-bearing area of the sub-groups of the Chang 71 and Chang 72 reservoirs was determined to be 20.829 km2and 18.732 km2,respectively.The volume-method was used to calculate the Chang 7reservoir reserves of 398.91×104t.4)Using the petrel geological modeling software,a combination of deterministic modeling and stochastic modeling with constraints on sedimentary microfacies,a structural model,phase model,and attribute models to the Chang 7tight reservoir in the Dongrengou block was established.Among them,all the porosity model,permeability model and oil saturation model have a good consistency in distribution.The sand body is in an isolated elliptical,lenticular,or isolated belt plane.The long axis is parallel to the paleocurrent,and the northeast source direction is significant.Comprehensive reservoir development characteristics and property modeling results show that the Dongrengou Chang 7 reservoir shows strong heterogeneity. |
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