Shale Deposits And Reservoir Characteristics Of Gufeng And Dalong Formations In Permian In Western Hubei

With the deepening of shale gas research,the global interest in shale gas is increasing.China also has rich shale gas resources.However,the current domestic research on shale gas is focused on the Wufeng-Longmaxi Formation.The results show that the Permian Gufeng Formation and Dalong Formation in the western Hubei region have developed typical black shale,and have good shale gas enrichment conditions.It is beneficial to expand the horizons and fields of shale gas research.In this paper,based on the previous research,combined with the latest drilling and field profile data,and based on the knowledge of sedimentology and other related disciplines,comprehensive test and analysis results are carried out to determine the types of shale,sedimentary facies,The characteristics of mineral composition and pore type were studied in depth,and the favorable reservoir facies zone of the two layers on the study block was summarized.The stratigraphic characteristics of the Permian Gufeng Formation and Dalong Formation in the western Hubei area were studied.The lithology of the Gufeng Formation and Dalong Formation is mainly black carbon mudstone,silty mudstone,siliceous mudstone,etc.Combining with the signs of sedimentary facies,it is believed that the depositional environment of Gufeng Formation and Dalong Formation is mainly continental shelf environment and basin(basin)deposition system.Pyrite is commonly developed in the Gufeng and Dalong Formations,and the output morphology also varies with the location and area.The two forms are strawberry-like pyrite and honeycomb-like pyrite,indicating that the study area is A closed-semi-closed hypoxic reducing environment.In-depth and systematic study of the reservoir characteristics of the Permian Gufeng Formation and Dalong Formation in the western Hubei area.Various test analysis data show that the two layers have high brittle mineral content and develop clays such as chlorite and illite.Minerals mainly develop pore types such as intragranular pores and intergranular pores.The pore size is between 0.5um and 20 um,and the porosity is generally not high,between 0.7% and 5%.It is generally high,with favorable conditions for shale gas formation,and a wide range of TOC content.The TOC content in the upper part of each horizon is significantly higher than that in the lower part,and it gradually decreases from top to bottom.Based on "multi-parameter" evaluations such as lithological characteristics and organic geochemical characteristics,combined with analysis of favorable sedimentary facies zones,optimization of favorable reservoir facies zones of organic-rich shale in different layers was carried out.A total of 2 favorable phase zones are selected.