Genetic Mechanism And Distribution Prediction Of Deep High-quality Reservoirs Of Gaoliu Area In Nanpu Sag

Based on the methods and means of petrology,mineralogy and geochemistry,this paper has systematically studied the petrology characteristics,diagenesis characteristics and main control factors of deep reservoirs in Gaoliu area of Nanpu sag.Based on the main controlling factors of different types of sandstone reservoirs,combined with diagenetic evolution process,burial history and thermal history in the study area,the formation mechanism of different types of sandstone reservoirs is analyzed,the formation model is summarized,and the reservoir of the Es₃ formation in Gaoliu area of Nanpu sag is predicted.The main results are as follows:The sandstone reservoir types in the study area are mainly lithic sandstone and feldspathic lithic sandstone.Through the observation of casting thin section,it can be seen that the reservoir pores are mainly secondary dissolution pores,and part of them are primary pores.The reservoirs of Es₃ formation have experienced a long and complex diagenetic evolution processes and is now in the middle diagenetic A₂ stage.Compaction is the most important pore reducing diagenesis in the study area,and secondary dissolution greatly improves the physical properties of the reservoir.The abnormal high porosity development zone belongs to the secondary dissolution porosity development zone dominated by secondary porosity.According to the different sedimentary characteristics,physical properties characteristics,diagenetic facies types and pore structures of the reservoirs in the study area,the deep sandstone reservoirs in Gaoliu area of Nanpu sag can be divided into four types,among which the type I and the type II are high-quality reservoirs in the study area,the type III can be used as effective reservoirs,and more than 80%of the type IV are dry reservoirs,which are not effective reservoirs and is no value of exploration and exploitation under current economic conditions.The reservoir heterogeneity is very obvious in the study area,which is mainly caused by different source types,sedimentary microfacies characteristics,various diagenesis,complex pore structure,abnormal pressure with uneven development and uneven hydrocarbon filling.The sedimentary microfacies affect the effectiveness of the reservoir,the underwater distributary channel in the front of fan delta is the most favorable sedimentary microfacies,which develops abnormally high porosity zone and high porosity zone;diagenesis and provenance characteristics affect the development of abnormally high porosity zone,and the reservoir originated from the northwest edge of Baigezhuang fault is more likely to develop effective reservoir,while the strong dissolution facies which developed strongest sissolution develop the best quality class ? and class ? reservoirs.