| This thesis take the Tazhong 4 Oilfield Bioclast Limestone Member of Lower Carboniferous as the main research target,make full use of the basic geological data,the integrated application of core,thin section,well logging and logging data,in carbonate reservoir geology,sedimentary petrology,modern stratigraphy and other multidisciplinary theory as the basis,combining previous research results,a brief overview of the stratigraphic features,sedimentary characteristics,the key to deepen the understanding of reservoir characteristics,has been clear about the reservoir control factors,investigate the influence of porosity evolution of reservoir development,ultimately good for reservoir distribution characteristics and development areas.According to the study,the thickness of bioclast limestone Member in the study area gradually decreases from west to east.The type of sedimentary facies is carbonate platform,which can be further divided into three subfacies of evaporation platform,restricted platform and semi-confined platform.The sedimentary facies which is most conducive to the formation and evolution of the reservoir is the microfacies of dolomitic flat in the subfacies of evaporative terrace,followed by the microfacies of all kinds of shoals in the subfacies of the restricted platform and semi-restricted platform.The main reservoir space types are intercrystalline pores,intergranular pores and caverns.The physical properties of dolomite are significantly better than those of limestone.The deposition of bioclastic limestone in the study area experienced three stages:contemporaneous stage,early diagenetic stage,and late diagenetic stage.The pore evolution experienced sedimentary stage,quasi-contemporaneous stage,regional groundwater-shallow burial stage,and mid-deep burial stage.Among them,constructive diagenesis is mainly quasi-solitonic dolomitization,atmospheric water-solubility erosion,structural fracture and dissolution in the buried period.The paper evaluates and predicts the favorable reservoir zone of the Carboniferous bioclastic limestone section in the study area.The type Ⅰ zone is a dolostone-porosity type reservoir development zone,located in the evaporite mesophase zone;Type Ⅱ is a particulate ash.Rock and dolomitic limestone fracture-cavity reservoir development zone is in the confined plateau facies zone;Class Ⅲ zone is mudstone limestone,grain limestone,plaster limestone fracture-porosity and fractured reservoir development zone Type Ⅳ non-reservoir areas are roughly distributed in the semi-constraint plateau phase zone.The lithology is dominated by mudstone and argillaceous limestone,with dense lithology and poor physical properties. |
