Diagenesis And Its Control On Reservoir Quality Of Middle-Lower Ordovician In Area Of Shunnan

Based on core,thin slice,well logging,geochemical and seismic data,author analyzes the characteristics and main controlling factors of the carbonate reservoirs in the Middle-Lower Ordovician in Area of Shunnan The results show that the main types of rock of the carbonate reservoirs in the study area are limestone,dolomite,transitional rocks and siliceous rocks.The target stratum can identify 4 kinds of sedimentary facies,such as restricted platform,open platform,platform edge,and platform slope,and further subdivide 8 subfacies and 12 microfacies.The research area has experienced a very complex diagenesis,with a constructive diagenesis as silicification,(quasi)same as atmospheric water-solubility erosion,and structural hydrothermal dissolution.Cementation is the diagenesis that mainly destroys reservoir development.The reservoir space of the Middle-Lower Ordovician reservoir is dominated by pores,karst caves,and fractures.Combined with the characteristics of reservoir space,the reservoir types in the region can be divided into fracture-porosity reservoirs,fracture-cavity reservoirs,and fractures.Reservoirs.lithology,sedimentary facies,diagenesis and fractures are the main controlling factors in the formation of reservoirs in the target stratum.Among them,siliceous rocks and dolomites provide core foundations for the development of high-quality reservoirs.The development of high-energy shoal in the basin has laid the material foundation for selective dissolution in the later stages.The light water-solubility erosion and dissolution in the buried period have improved to some extent.The reservoir performance of the Middle-Lower Ordovician,and the multiple sets of NE-trending and NNE-trending faults developed in the area are the key to the formation of high-quality reservoirs.