Research On Carbonate Reservoir Characteristics Of The Ordovician Yingshan Formation In Tazhong ZG51 Area

The Tazhong area is located at the central uplift of the Tarim Basin.The fault systems of the study area are complex.The reservoirs within Yingshan Formation are porous with well-developed fractures and cavities.The controlling factors of these reservoirs are still uncertain,therefore,it is of practical significance to carry out research on their characteristics.The Yingshan Formation has deep burial depth,complex sedimentary system,unclear development principle of fracture,and poor seismic resolution.The study of reservoir characteristics is mainly based on the single well analyses to reveal the sedimentological features of target resevoirs.This thesis proposes a fracture modelingmethod,based on the development features of fractures and uses the proposed model to predict the distribution of the fractures in unknown area.Finally,this thesis summarizes the characteristics of all types of the fractures to serve as an analogue for other studies.The petrophysical characteristics of the target reservoir are studied by integrated analyses of the dynamic and static features of core,thin section,and petrophysical tests.Reservoir diagenesis,reservoir space type and influencing factors are summarized.The Marine sedimentary environment and open platform facies are the main sedimentary environments in the study area.There are four types of rocks: granular limestone,micritic limestone,biolimestone and dolomite.Diagenesis mainly includes dissolution,karstification and metasomatism.There are three main types of reservoir space:caves,cavities and fractures.Taking core,imaging log and other data as hard data,a large number of data samples are comprehensively analyzed to summarize the development rules of major reservoir Spaces such as fractures and cavities,and to define parameters such as fracture occurrence,strike,dip and dip Angle.The advantages and disadvantages of various fracture modeling methods were analyzed,and finally,the idea of fracture modeling with fracture development law as the constraint condition and DFN modeling as the main method was established.The fracture development characteristics revealed by a single well were applied to the whole area,and the fracture distribution characteristics were simulated in the three-dimensional space.Based on the comprehensive analysis of the model,the closer the fault plane is and the larger the deformation of fault plane is,the denser the distribution of fractures is.The higher the curvature,the more developed the fracture and the higher the fracture linear density.The closer to the boundary fault plane,the higher the porosity and permeability of the derived or associated fractures.Based on the analysis of a large number of research results and the distribution law of fracture model in three-dimensional space,the influence of controlling factors such as lithology,lithofacies,diagenesis,bedrock physical properties and fractures on the distribution of dominant reservoirs is clarified.The reservoirs of type ? and ? are the best,followed by type ?,and the type ? is the worst.Overall physical properties of the reservoirs within Yinshang Formation are good to moderate.