Reservoir Characteristics And Modeling Of Yingshan Formation In Zhonggu 6 Well Area In Central Tazhong Area

This paper,guided by the principles of carbonate sedimentology,reservoir geology and structural geology,applying core,thin section,drilling,logging and seismic data,adopting multi-disciplinary and multi-means integrated analysis method,based on Yingshan formation and sedimentary facies analysis of Zhonggu 6 wellblock in Central part of Tarim basin,study the reservoir characteristics from the reservoir petrology,reservoir space and physical properties,analyse the horizontal and vertical distribution characteristics and major control factors.Applying drilling,seismic,logging physical properties and the wave impedance inversion data,adopt sequential Gaussian simulation algorithm to establish structure model,porosity model and permeability model.The main results are as follows:1)Ying 1 member of Yingshan Formation in Middle-Lower Ordovician can be subdivided into five mebers,as layer 1st to 5th from top to buttom.Deposition thickness of layer 2nd and 4th is small,generally within 10-24m.The thickness of the rest layer 1,3,5 is larger,within 60-125m.From the north to south,the denudation degree of Yingshan Formation increase gradually and the residual stratum thickness gradually reduce.Yingshan Fomation is open platform facies,characterized by transgressive-regressive cycles of intra-platform shoal and interbank sea vertically and large area of good-continuity,high-energy sand flocks beach deposition horizontally.2)The rock type of reservoirs in Yingshan Formation in the study area is dominated by bright crystal calcarenite,accounted for 43.7%,followed by the mud crystal sand-clastic limestone and micritic limestone,respectively,accounting for 18.4%and 22.7%.Resevoir space types main concludes macro-pores such as cave and corrosion vug and fractures,and micro-pores such as intergranular dissolved pores,intragranular dissolved pores,moldic pores intercrystalline pores,intercrystalline solution pores,micro-fractures.Physical characteristic present generally low porosity and permeability.Logging porosity,between 1.8%and 4.5%,account for about 69.6%.Fracture porosity,less than 0.3%,account for about 79.4%.Logging permeability,ranging in 0.01-3mD,account for about 87.5%.3)Reservoirs mainly lie in layer 3 and 5 of Ying1 member.? type,? type and ? type,respectively,account for 10%,22%,68%in layer 3;which contains continuous reservoirs with different thickness in different area.The thickness of reservoirs in layer 5 is less than in layer 3.The thickness of ? type,? type and ? type,respectively,account for 2%,44%,54%.Reservoirs presented isolated shape distribution and are not continuous.Reservoir is mainly controlled by sedimentary facies,karstification and tectonic fracture.High energy of sand flocks beach,as favorable sedimentary phase,is the foundation of the development of reservoir.Crust karst and burial dissolution is the key of controlling development and distribution of reservoirs.Structural fault can improve the reservoir permeability.4)The structure model shows that the formation are deep and gentle in the northwest,and presents lower at well Zhonggu 503.The formation of the southeast is shallow and steep,and presents higher at well Zhonggu 7.Porosity and permeability model shows that,the higher porosity areas of layer 3 mainly lie in the area of well Zhonggu 5-Zhonggu 9,well Zhonggu 7-Zhonggu 701,well Zhonggu 1-Zhonggu 601 and well Zhonggu 6-Zhonggu 6-2,and the higher permeability areas mainly lie in the area of well Zhonggu 5-Zhonggu 9-Zhonggu 1 and well Zhonggu 4-Zhonggu 6 The favorable reservoir areas of layer 3 may lie in the area of well Zhonggu 5-Zhonggu 9,well Zhonggu 1-Zhonggu 601 and well Zhonggu 4-Zhonggu 6 The higher porosity areas of layer 5 mainly lie in the area of well Zhonggu 9-Zhonggu 5-1,well Zhonggu 1-Zhonggu 601,north of well Zhonggu 701 and well Zhonggu 5,and the higher permeability areas mainly lie in the area of well Zhonggu 1-Zhonggu 601-Zhonggu 6 and near well Zhonggu 5.The favorable reservoir areas of layer 5 may lie in the area of well Zhonggu 1-Zhonggu 601,north of well Zhonggu 701 and northeast of well Zhonggu 501.