Geological Modeling Of The Upper Ordovician Carbonate Reservoir With No. 10 In Tazhong

Under the guidance of carbonate reservoir geology,sedimentary petrology and structural geology,and the geologic modeling,this paper comprehensively used the data of core,thin slice,logging and earthquake,etc.,to perform the stratum,petrologic features,sedimentary facies features and reservoir characteristic system for the reef flat in Lower Ordovician on Tazhong Structure 10.On the basis,the appropriate modeling approach was selected to establish the reservoir porosity and permeability models.Finally,the favorable exploration area of reservoir was comprehensively predicted through the study on sedimentary facies,basic characteristics of reservoir and three-dimensional reservoir geological model,combined with the distribution characteristics of seismic reflection type.The main results of this paper are as follows:The Lianglitage Formation in Lower Ordovician on Tazhong Structure 10 is divided into five sections from top to bottom with open platform as the depositional setting:Liang Ⅰ,Ⅱ and V sections are the high-energy deposition,and Liang Ⅲ and Ⅳ are the low-energy deposition.Reservoir rock types include the calcarenite,bioclast calcarenite,bioclast limestone,bondstone,micrite,cryptomonas mudstone and oolitic limestone,among which the calcarenite in the reservoir is the most developed(46%),followed by bioclast calcarenite(25%).The reservoir spaces include the macroscopic patterns,such as corrosion holes,corrosion holes,tectonic fissures and corrosion fissures,and microscopic patterns,such as intragranular pores,mold pores,intergranular pores and microcracks.The reservoir belongs to the low porosity and low permeability type,and the porosity less than 4%accounts for 86.4%with an average value of 2.1%,and the permeability is between 0.01mD and 0.1mD,accounting for 60.2%,with an average value of 0.084mD;in the study area,the reservoir types include the porosity type(61%),fractured type(6.8%),cave type(0.4%)and fracture-pore type(31.8%).The reservoir levels include the Class Ⅲ(80.2%),Class Ⅱ(17.8%)and Class Ⅰ(2%).Combined with the sedimentary facies,diagenesis,structure and other reservoir controlling factors,the favorable area of reservoir is predicted.The results show that the reservoir shows the zonal distribution from northwest to southeast,and the Class Ⅲfavorable areas are in Zhonggu well block 44,Tazhong well block 201,Zhonggu well block 43,Zhonggu well block 51 and Tazhong well block 12,showing the reunion distribution.In this paper,the collaborative sequential Gaussian stochastic simulation was used to establish the stratum,reservoir porosity and permeability models.The development of porosity and permeability has the significant position.The porosity and permeability in Liang 1 and Liang 2 sections are developed well,but those in Liang 3 to Liang 5 sections are developed poorly;the porosity and permeability in Liang 1 section are not continuous and interrupted,but those in Liang 2 section are continuous well.